HEPARIN (mucolytic action)



MANNITOL (as a mucolytic)


N-ACETYLCYSTEINE (for intestinal use)




1961 Chernick WS, Barbero GJ, Eichel HJ. In vitro evaluation of the effect of enzymes on tracheobronchial secretions from patients with cystic fibrosis. Pediatrics 1961; 27:589-596. [PubMed]
Effect of various enzymes on the viscosity of CF sputum showed that pancreatic dornase had the most marked effect showing complete dissolution of the fibrous structure of the sputum. This finding supported the theory that the excessive viscosity of CF sputum (figure 1) was related to a fibrous network observed in the sputum which was primarily of deoxyribonucleoproteins as had been shown by this group (Chernick et al, 1959 above).
The effect of enzymes on the sputum had been reported in other chronic pulmonary conditions (Sherry S et al. Proc Soc Exp Biol Med 1948; 68:179-184.[PubMed]) and also on CF sputum (Shwachman & Leubner, 1955 above). These and other early studies eventually led to the introduction of rhDNase (Pulmozyme) as an effective mucolytic but only after the side effects of the biological product were circumvented by producing this genetically engineered product rhDNase (Pulmozyme) (Shak et al, 1990 below).

Armstrong JB and White JC (Lancet 1950; 2:739-742. [PubMed]) had shown that deoxyribonuclease would liquefy viscous purulent exudate; later Elmes PC & Armstrong JB (Thorax 1953; 8:295-300.[PubMed]) reported its use in chronic bronchitis, but the side effects of the bovine preparation precluded its use and further development (Raskin P. Am Rev Respir Dis 1968; 98:697-698.[PubMed]). Shwachman (1955 above) mentions that May and Lowe used a pancreatic preparation by inhalation in one patient and that at autopsy widespread granulomatous lesions were found in the lung, a lesion not seen in any other patient. However, eventually Shak et al (1990 below) cloned, sequenced, and expressed rhDNase which later became one of the major advances in treatment of the Nineties (Fuchs et al. 1994 below).

1961 Reid L. The composition of tracheobronchial secretions in cystic fibrosis. Postgrad Med J 1961; 37:599-600. [PubMed]

Lynne Reid

Professor Lynne Reid’s first academic appointment was as a research assistant at the Institute of Diseases of the Chest at London University (figure). She was appointed a professor of experimental pathology at London University in 1967, and was made Dean of the Cardiothoracic Institute at London University in 1973. She accepted a position on the faculty of Harvard Medical School in 1976, as one of the school’s few women faculty members. Most of her publications concerned the bronchial secretions and the characteristics of bronchial mucous glands. These were popular areas for research for the few researchers involved in CF at the time, so copious and so very viscid was the sputum of people with cystic fibrosis. As it eventually turned out there were no intrinsic structural abnormalities of the mucus. During her time in the UK she was a good friend to and  closely involved with the UK Cystic Fibrosis Research Trust. Lynne Reid reviewed much of her research in 1981 at the Minnesota Meeting (1000 Years of Cystic Fibrosis. University of Minnesota, 1981).

1962 Lieberman J. Enzymatic dissolution of pulmonary secretions. An in vitro study of sputum from patients with cystic fibrosis of the pancreas. Am J Dis Child 1962; 104: 342-348.[PubMed]

Jack Lieberman

Dr Jack Lieberman of Los Angeles observed that a favourable effect on sputum viscosity by the addition of enzymes had been reported both in vitro (Chernick et al, Pediatrics 1961; 27:589 above) and in vivo (Shwachman et al. Pediatrics 1960; 25:155-163.[PubMed]).
This present study confirmed the liquefaction which occurred in the presence of various enzymes in order of effect – trypsin, ficin, chymotrypsin, deoxyribonuclease and elastase.

There was an interesting editorial comment to this article as follows – “Now if someone can find a way to bring a sufficient quantity of a non-irritating mixture of enzymes to bear on the bronchiolar mucus he can see if it works in the patient”. This did eventually occur with rhDNase (Pulmozyme) but it was some 30 years before this was achieved (Shack et al. 1990; Fuchs et al, 1994 below). (Also Lieberman J. JAMA 1968; 205:312-313 below).

1963 Denton R. The rheology of human mucus. Ann N Y Acad Sci 1963; 106:746-754. [PubMed]
This is a relevant paper as the work of Robert Denton was important in the introduction of the mist tent. The paper concludes with the seemingly obvious statement that the degree of flow resistance will show as quantitatively the degree of abnormality and may provide information which can lead to further understanding of the chemical changes within the mucus blanket which are responsible for impaired bronchial drainage.

1963 Chernick WS, Barbero GJ. Studies on human tracheobronchial and submaxillary secretions in normal and pathophysiological conditions. Ann N Y Acad Sc 1963; 106:698-708.[PubMed]

     Giullo Barbero

The authors state – “Data relating to the tracheobronchial secretions and submaxillary saliva in cystic fibrosis indicate the high concentrations of various organic constituents which are secreted in this disease and the possible interrelationships of electrolytes on the physical properties of such constituents”.

So, as with most of these studies on the physico-chemical characteristics of the airway secretions, there were no firm conclusions which significantly advanced understanding of the basic defect of the condition. It is interesting that these authors again mentioned the possible role of the electrolyte content of the sputum which eventually turned out to be very relevant.

Professor Giulio Barbero (figure) was internationally recognised for his research in CF and patient advocacy. He published extensively on CF and general paediatric topics from 1953 to 2001. He was Head of Pediatrics at the University of Missouri, Columbia from 1972-1989. He gave the third Joseph Levy Memorial Lecture at the European CF Meeting in Jerusalem in 1996 entitled “The Science and Humanity of Cystic fibrosis”.

1963 Kwart H, Mosley WW Jr, Katz M. The chemical characterization of human tracheobronchial secretion: a possible clue to the origin of fibrocystic mucus. Ann N Y Acad Sci 1963; 106:709-21. [PubMed]
One of many studies that attempted to show differences between normal and CF mucus. The authors summarise that their findings appear to support the basis for the disease they had advanced earlier i.e. that the extraordinary viscidity of CF mucus was formed as a result of a defect in “membrane chemistry”. They consider that the inference is consistent with the difficulties that CF individuals experience conserving sodium chloride.

So another group whose conclusions were not too far off the mark as it turned out. However, in contrast to the excessive loss of salt via the sweat people with CF had a deficiency of salt in the airway secretions due to the excessive absorption of sodium and reduced passage of chloride into the airways.

1963 Matthews LW, Spector S, Lemm J, Potter JL. Studies on pulmonary secretions I. The over-all chemical composition of pulmonary secretions from patients with Cystic Fibrosis, Bronchiectasis and Laryngectomy. Am Rev Resp Dis 1963; 88:199-204. [PubMed]
Leroy Matthews was one of the leading clinical authorities on CF in the USA at the time. He was developing his Comprehensive Treatment Programme in Cleveland which was to become the model for CF care adopted by the CF Foundation for their Centres programme. In this study they found that total solids, DNA protein, lipid and carbohydrate were highest in CF secretions, intermediate in non-CF bronchiectasis and lowest in normals.
The marked decrease in sodium and chloride in CF sputum which they found they considered was possibly related to the infection – “if this is so it makes untenable the hypothesis that the lowered sodium and chloride content of the cystic fibrosis secretions is etiologically responsible for the disease”.

This is interesting for later the “low salt theory” was to be regarded as the most likely explanation for the alteration in the pulmonary secretions and the persisting pulmonary infection problems.

1975 Wood RE, Wanner A, Hirsch J, Farrell PM. Tracheal mucociliary transport in patients with cystic fibrosis and its stimulation by terbutaline. Am Rev Respir Dis 1975; 111:733-8.[PubMed]

        Robert Wood

Robert Wood observed the movement of Teflon discs passing up the trachea through a bronchoscope in 14 adults with cystic fibrosis. The discs moved at 2.6 mm/min in CF and 20.1 mm/min in controls; terbutaline increased the speed of movement in CF to 5.5mm/min. The authors speculated, correctly as it has now become apparent, that this “may play a role in the pathogenesis of pulmonary disease”.

Robert Wood pioneered fibreoptic bronchoscopy in children with CF. The 3.5mm paediatric version of the bronchoscope he used in 1975 had no suction port which he circumvented by attaching a fine Teflon tube to the side allowing its use down to children aged 18 months; it was developed by the Olympus Corporation into the first flexible pediatric bronchoscope in 1978 at Dr Wood’s request.


A number of earlier papers examined the effect of heparin on cilial activity etc. More recently publications have concerned mucolytic activity. The papers concerning the use of heparin as an anticoagulant for intravenous work – heparin lock etc – are not reviewed here.

1973 Doggett RG, Harrison GM, Patrick TA. Cystic fibrosis: in vivo reversal of ciliostatic character of serum and parotid secretions by heparin. Nat New Biol. 1973; 243:250-251. [PubMed]
Reversing the effect on the “CF factor” which reduced the beating of cilia.

1982 Margolies R, Gray B, Boat TF. Identification of a major heparin-precipitable protein in human serum and its relationship to cystic fibrosis. Pediaitr Res 1982;16:181-186[PubMed]
Heparin binding to serum proteins and their subsequent precipitation is reportedly increased in cystic fibrosis. We have confirmed this finding for CF patients over the age of 12 ; patients with a variety of pulmonary diseases unrelated to CF do not show this effect. In addition, the report that young CF patients exhibit hypogammaglobulinemia prompted the authors to examine serum samples from CF patients and age-matched controls under the age of 12. No differences were found. When serum from all donors was fractionated by Staph A-Sepharose into IgG and non-IgG fractions, 85-89% of heparin precipitable protein was in the IgG fraction.

This paper was published when there was little information available as to the likely basic defect.

2001 Ledson M, Gallagher M, Hart CA, Walshaw M. Nebulized heparin in Burkholderia cepacia colonized adult cystic fibrosis patients. Eur Respir J 2001; 17:36-38. [PubMed]

 Malcolm Ledson

Heparin thins sputum by decreasing the mucin molecule amino group negative charge, altering its intermolecular

Martin Walshaw

hydrogen bonding, and ionically shielding its polyionic moieties. It also has an anti-inflammatory effect within the lung. It may, therefore, be useful in the treatment of CF patients. In order to test this, six fully informed Burkholderia cepacia colonized stable adult CF patients, received 25,000 IU nebulized heparin sulphate daily for 7 days. There was no change in spirometry, but a reduction in interleukins (sputum IL-6, p=0.01; sputum IL-8, p=0.002; serum IL-6, p=0.02; serum IL-8, p=0.02). Sputum was easier to expectorate (p < 0.04), with a trend towards thinner sputum (p=0.07) but no change in sputum volume.

Heparin therapy was well tolerated and had an anti-inflammatory effect, with subjective sputum mucolysis. The authors suggested further studies were necessary to define the role of heparin in the treatment of cystic fibrosis patients.

There were no further publications from Liverpool on the use of nebulised heparin.

Drs. Martin Walshaw and Malcolm Ledson formed and built up the Liverpool CF Centre for Adults.

2006 Serisier DJ, Shute JK, Hockey PM, Higgins B, Conway J, Carroll MP. Inhaled heparin in cystic fibrosis. Eur Resp J 2006; 27:354-358. [PubMed]
In people with CF inhaled heparin 50,000 IU twice daily had no effect on FEV1, sputum clearance or inflammatory markers. Ledson et al (Eur Respir J 2001; 17:36-38) from Liverpool had reported that inhaled heparin had no effect on 6 patients with CF who had B. cepacia infection. The present authors stated that “Heparin thins sputum by decreasing the mucin molecule amino group negative charge, altering its intermolecular hydrogen bonding, and ionically shielding its polyionic moieties. It also has an anti-inflammatory effect within the lung”.

It seems unlikely that this would prove to be a significant advance in treatment. Although the authors suggested that heparin was safe and future evaluation of larger doses over a longer period may be warranted, it is perhaps significant that neither of the CF centres involved in these studies are using the heparin treatment on a regular basis.

2007 Broughton-Head VJ, Shur J, Carroll MP, Smith JR, Shute JK. Unfractionated heparin reduces the elasticity of sputum from patients with cystic fibrosis. Am J Physiol – Lung C 2007; 293:L1240-9. [PubMed]
Unfractionated heparin (UFH) significantly reduced the elasticity and yield stress, but not the viscosity, of CF sputum from patients not receiving dornase alfa therapy. Heparin dose-dependently significantly increased the diffusion of nanospheres through CF sputum from patients not on dornase alfa therapy from 10.5 +/- 2.5% at baseline to 36.9 +/- 4.4% at 10 mg/ml but was more potent, with maximal effect at 0.1 mg/ml, in patients who were on dornase alfa therapy.

Thus the mucoactive properties of UFH indicate its potential as a new therapeutic approach in patients with cystic fibrosis.

2007 Zappala C, Chandan S, George N, Faoagali J, Boots RJ. The antimicrobial effect of heparin on common respiratory pathogens. Crit Care Resusc 2007; 9:157-160[PubMed]
The mucolytic, anticoagulative, anti-inflammatory and neo-angiogenic properties of inhaled heparin may benefit patients with burns and cystic fibrosis. We assessed the antibacterial effects of unfractionated heparin.

Heparin produced dose-dependent growth inhibition of three of seven S. pneumoniae isolates (complete inhibition at 2500U dose per 200 microL) and one of five H. influenzae isolates (complete inhibition at 7500 U dose per 200 microL), but no inhibition of other isolates.

The authors concluded that unfractionated heparin is unlikely to have antibacterial effects because of its unpredictable inhibition of growth of common respiratory pathogens.

2008 Shur J, Nevell TG, Shute JK, Smith JR. The spray drying of unfractionated heparin: optimization of the operating parameters. Drug Dev Ind Pharm 2008; 34:559-568. [PubMed]
In this study, unfractionated heparin has been spray-dried to produce spherical micronised particles in the size range 1-5 microm, which is suitable for delivery by dry-powder inhalation. Spray drying parameters have been optimized using a 2(4) factorial experimental design. The feed concentration and atomisation spray flow rate have the greatest effects on recovery (typically 60%) and particle size.

2008 Shur J, Nevell TG, Ewen RJ, Proce R, Smith A, Barbu E, Conway JH, Carroll MP, Shute JK, Smith JR. Cospray-dried unfractionated heparin with L-leucine as a dry powder inhaler mucolytic for cystic fibrosis therapy. J Pharm Sci 2008; 97:4857-68.[PubMed]
Unfractionated heparin (UFH) has mucolytic properties suggesting that it may be a useful therapeutic agent for lung disease in these patients. For the pulmonary delivery of UFH to patients with CF, the dry powder inhaler has potential advantages over systems using nebulised suspensions. However, spray-dried particles in the appropriate size range (1-5 microm) may absorb atmospheric moisture, causing aggregation. UFH has been cospray-dried with L-leucine (1%, w/w) to produce particles that are less cohesive than UFH alone and show good aerosolisation performance. Rheological analysis has shown that spray-dried UFH and UFH cospray-dried with L-leucine significantly (p < 0.05) reduce the elasticity and yield stress of CF sputum. The superior physical properties of UFH/L-leucine indicate this is the preferred formulation for development as an inhaled mucolytic.

There were no further reports of the use of this heparin preparation from Southampton/ Portsmouth by 2013.


By 2012 60.4% of US patients aged 6 years or more were taking regular hypertonic saline

1996 Robinson M, Regnis JA, Bailey DL, King M, Bautovich GJ, Bye PTP. Effect of hypertonic saline, amiloride, and cough on mucociliary clearance in patients with cystic fibrosis. Am J Respir Crit Care Med 1996; 153:1503-1509.[PubMed]
After inhalation of hypertonic (7%) saline alone, and with amiloride, the amount of radio aerosol cleared from the right lung at 60 and 90 minutes was significantly increased. The authors suggested that inhaled hypertonic saline was a potentially useful treatment for CF. Peter Bye’s group at the Adult CF Centre at St Vincent’s Hospital in Sydney continued their work on hypertonic saline and eventually carried out a successful clinical trial of hypertonic saline in adults with CF and eventually confirmed the value of hypertonic saline treatment (Elkins et al, 2006 below).

Hypertonic 7% saline inhalations were originally reported to double the rate of removal of bronchial secretions in chronic bronchitis in an interesting study using radio aerosols (Pavia et al, Am Rev Respir Dis 1978; 117:199-203.). I recall consulting Margaret Hodson in the early Eighties asking her for any suggestions for treating a girl with CF who had excessively viscid secretions. She advised a trial of nebulised hypertonic saline which, from her personal experience, had proved helpful!!

1996 Riedler J. Reade T. Button B. Robertson CF.Inhaled hypertonic saline increases sputum expectoration in cystic fibrosis. J Paediatr Child H 1996; 32:48-50. [PubMed]
Ten adolescents with CF, who were receiving inpatient treatment for a pulmonary exacerbation, were enrolled in a controlled cross-over clinical trial. After inhalation of beta adrenergic drug to prevent possible broncho-constriction, each patient inhaled for 10 min either 0.9% isotonic saline (IS) or 6% HS prior to routine physiotherapy. The following day the patient received the alternative solution. Seven patients undertook a second block after 1-5 days. Outcome measures included weight of sputum, a visual analogue score to assess the subjective feeling of a cleared chest after physiotherapy, and spirometry.

Sputum expectoration (median; Q1,Q3) from the beginning of the inhalation of HS or IS to the final spirometry measure 60 min post-physiotherapy was significantly greater after HS than IS [17.2g (11.7, 34.8) vs 11.3g (6.5, 16.1): P = 0.006]. A clinical score of the patient’s own judgement of a cleared chest was significantly better after HS than IS. Spirometry results did not change following either of the two inhalations.

The authors concluded that these data show that the inhalation of 6% HS prior to physiotherapy can increase sputum expectoration in patients with CF and suggest that HS might be an effective, safe and cheap adjunct to regular physiotherapy in patients with CF.

2001 Suri R. Metcalfe C. Lees B. Grieve R. Flather M. Normand C. Thompson S. Bush A. Wallis C. Comparison of hypertonic saline and alternate-day or daily recombinant human deoxyribonuclease in children with cystic fibrosis: a randomised trial. Lancet 2001; 358(9290):1316-21. [PubMed]
Daily recombinant human deoxyribonuclease (rhDNase) is an established but expensive treatment in cystic fibrosis. Alternate-day treatment, if equally effective, would reduce the drug cost. Hypertonic saline improved lung function to the same degree as rhDNase in short-term studies. We compared the effectiveness of daily rhDNase, hypertonic saline, and alternate-day rhDNase in children with cystic fibrosis.

In an open cross-over trial, 48 children were allocated in random order to 12 weeks of once-daily rhDNase (2.5 mg), alternate-day rhDNase (2.5 mg), and twice-daily 5 mL 7% hypertonic saline. The primary outcome was forced expiratory volume in 1 s (FEV(1)). Secondary outcomes were forced vital capacity, number of pulmonary exacerbations, weight gain, quality of life, exercise tolerance, and the total costs of hospital and community care.

Mean FEV(1) increased by 16% (SD 25%), 14% (22%), and 3% (21%) with daily rhDNase, alternate-day rhDNase, and hypertonic saline, respectively. There was no difference between daily and alternate-day rhDNase (2% [95% CI -4 to 9], p=0.55). However, daily rhDNase showed a significantly greater increase in FEV(1) than hypertonic saline (8% [2 to 14], p=0.01). The average difference in 12-week cost between daily and alternate-day rhDNase was pound513 (95% CI -546 to 1510) and that between daily rhDNase and hypertonic saline was 1409 pounds sterling (440 to 2318). None of the secondary clinical outcomes showed significant differences between treatments.

The authors concluded that hypertonic saline, delivered by jet nebuliser, is not as effective as daily rhDNase, although there is variation in individual response. There is no evidence of a difference between daily and alternate-day rhDNase.

2002 Ballmann M, von der Hardt H. Hypertonic saline and recombinant human DNase: a randomised cross-over pilot study in patients with cystic fibrosis. J Cyst Fibros 2002; 1:35-37). [PubMed]
The first evidence that there was a comparable increase in FEV1 with rhDNase and hypertonic saline. The authors commented that a larger study was required to confirm these findings.
This has not been the general experience – usually rhDNase appears to be the more effective.

2006 Elkins MR. Robinson M. Rose BR. Harbour C. Moriarty CP. Marks GB. Belousova EG. Xuan W. Bye PT. National Hypertonic Saline in Cystic Fibrosis (NHSCF) Study Group.A controlled trial of long-term inhaled hypertonic saline in patients with cystic fibrosis. N Eng J Med 2006; 354(3):229-40.[PubMed]

Mike Elkins

Test of the safety and efficacy of inhaled hypertonic saline in a long-term trial.    In this double-blind, parallel-group trial, 164 patients with stable cystic fibrosis who were at least six years old were randomly assigned to inhale 4 ml of either 7 percent hypertonic saline or 0.9 percent (control) saline twice daily for 48 weeks, with quinine sulfate (0.25 mg per milliliter) added to each solution to mask the taste. A bronchodilator was given before each dose, and other standard therapies were continued during the trial.

The primary outcome measure, the rate of change (slope) in lung function (reflected by the forced vital capacity [FVC], forced expiratory volume in one second [FEV1], and forced expiratory flow at 25 to 75 percent of FVC [FEF25-75]) during the 48 weeks of treatment, did not differ significantly between groups (P=0.79). However, the absolute difference in lung function between groups was significant (P=0.03) when averaged across all post-randomization visits in the 48-week treatment period.

As compared with the control group, the hypertonic-saline group had significantly higher FVC (by 82 ml; 95 percent confidence interval, 12 to 153) and FEV1 (by 68 ml; 95 percent confidence interval, 3 to 132) values, but similar FEF25-75 values. The hypertonic-saline group also had significantly fewer pulmonary exacerbations (relative reduction, 56 percent; P=0.02) and a significantly higher percentage of patients without exacerbations (76 percent, as compared with 62 percent in the control group; P=0.03). Hypertonic saline was not associated with worsening bacterial infection or inflammation.

The authors concluded that hypertonic saline preceded by a bronchodilator is an inexpensive, safe, and effective additional therapy for patients with cystic fibrosis.

2007 Subbarao P. Balkovec S. Solomon M. Ratjen F. Pilot study of safety and tolerability of inhaled hypertonic saline in infants with cystic fibrosis. Pediatr Pulmonol 2007; 42:471-6.[PubMed]
A prospective trial of inhaled HS in infants with CF. Raised volume rapid thoracoabdominal compression (RVRTC) maneuvers were performed at baseline, 10 min after salbutamol inhalation and 15 min after inhalation of a 7% HS solution. Oxygen saturation, respiratory rate, heart rate, and cough frequency were recorded during each inhalation. A clinically important change in lung function was defined a priori as a change in FEV 0.5 of > or =20%. Thirteen infants (5 female) aged 25-140 weeks were enrolled in the study.

Overall, there was no difference between FEV(0.5) or FEF(25-75) at baseline, after bronchodilator or after HS. Respiratory and heart rate as well as oxygen saturation remained stable during inhalation of the HS. Three infants had cough during inhalation; one of the infants woke up due to cough but recovered within 5 min. No other side effects were observed during or immediately after inhalation. There was no difference in microbiologic yield between pre- and post-HS throat swabs.

In this pilot study, inhalation of HS was well tolerated in CF infants. These results support a study of the efficacy of HS in this age group.

2008 Dellon EP. Donaldson SH. Johnson R. Davis SD. Safety and tolerability of inhaled hypertonic saline in young children with cystic fibrosis. Pediatr Pulmonol 43(11):1100-6.[PubMed]
Before conducting a therapeutic trial of HS in this population, its safety must be evaluated and protocols for monitoring response must be tested. The authors administered single dose 3% and 7% HS post-albuterol to 4-7 year-olds with CF able to perform spirometry (“preschool” group) and 4 month to 3 year-olds (“infant” group) using the raised volume rapid thoracoabdominal compression technique (RVRTC). Vital signs and cough episodes were measured after each inhaled treatment.

Eight preschool subjects (mean age 5.7 +/- 0.8 years) and 6 infants (1.6 +/- 1.0 years) completed the 3% HS protocol, and no clinically important change in vital signs or decrease in FVC, FEV(1), FEV(0.5), or FEF(25-75) occurred post-HS. Preschoolers had more cough episodes post-HS (P = 0.01). Seven preschoolers (6.1 +/- 0.7 years) and 8 infants (1.6 +/- 0.7 years) completed the 7% HS protocol. In the preschool group, FVC, FEV(0.5), and FEF(25-75) did not change significantly. A statistically significant drop in median FEV(1) occurred post-7% HS attributable to a transient >20% drop in one subject. Infant PFT parameters were unchanged post-7% HS. Preschoolers had more cough episodes post-HS (P = 0.03).

The authors concluded that and acute administration of 3% and 7% HS appears to be safe and well-tolerated in most young children with CF. Given the demonstrated benefits in older patients, a therapeutic trial in this age group is warranted.

2010 Amin R. Subbarao P. Jabar A. Balkovec S. Jensen R. Kerrigan S. Gustafsson P. Ratjen F.  Hypertonic saline improves the LCI in paediatric patients with CF with normal lung function.Thorax 2010; 65:379-83. [PubMed]
The objective was to study the ability of the lung clearance index (LCI), a measure of ventilation inhomogeneity, to detect a treatment response to hypertonic saline inhalation in paediatric patients with CF with normal spirometry.In a crossover trial, 20 patients with CF received 4 weeks of hypertonic saline (HS) and isotonic saline (IS) in a randomised sequence separated by a 4 week washout period. The primary end point was the change in the LCI due to HS versus IS.

Baseline characteristics including the LCI were not significantly different between both study periods. Four weeks of twice-daily HS inhalation significantly improved the LCI compared with IS (1.16, 95% CI 0.26 to 2.05; p=0.016), whereas other outcome measures such as spirometry and quality of life failed to reach statistical significance. Randomisation order had no significant impact on the treatment effect

The authors concluded that the lung clearance index, but not spirometry, was able to detect a treatment effect from HS inhalation in patients with CF with mild disease and may be a suitable tool to assess early intervention strategies in this patient population.

2011 Rosenfeld M. Davis S. Brumback L. Daniel S. Rowbotham R. Johnson R. McNamara S. Jensen R. Barlow C. Ratjen F. Inhaled hypertonic saline in infants and toddlers with cystic fibrosis: short-term tolerability, adherence, and safety.Pediatr Pulmonol 2011; 46:666-71.[PubMed]
A three-center, open label evaluation of the short-term tolerability, adherence, and safety of 7% HS administered twice daily for 14 days in children with CF 12-30 months of age. The primary objective was to evaluate the proportion of participants unable to tolerate single and repeated doses of 7% HS according to protocol-defined criteria. Participants inhaled a test dose of HS at the enrollment visit; test dose intolerance was defined as fulfillment of at least one of 4 criteria. Participants who tolerated the test dose inhaled 7% HS twice daily for 14+2 days.

RESULTS: Twenty children were enrolled. One was withdrawn due to maternal concern over fussiness with application of the facemask for the test dose. Of the 19 participants administered the test dose, 1 was withdrawn due to test dose intolerance (5%, 95% confidence interval 0, 26%). Eighteen participants completed the study; 1 was intolerant (95% CI 0, 27%) at the final visit due to new wheezes on exam in association with an upper respiratory infection and otitis media.

Home symptom diaries demonstrated cough as the main symptom in the hour following inhalation, which decreased in frequency over the study period. Adherence as assessed by daily home diary and returned study drug ampoules was high. Participants reported receiving both treatments on a median of 100% of days; a median of 25 ampoules were used during a median of 13 days.

The authors concluded 7% HS appears well tolerated for up to 14 days in infants and toddlers with CF, with high adherence. These results provide encouraging short-term tolerability and adherence data for future trials assessing the safety and efficacy of 7% HS in young children with CF.

2012 Pezzulo AA, Stoltz DA, Hornick DB, Durairaj L. Inhaled hypertonic saline in adults hospitalised for exacerbation of cystic fibrosis lung disease: a retrospective study.BMJ Open. 2012; 2(2):e000407. [PubMed]
The authors examined the tolerability and efficacy of hypertonic saline (HTS) use among adult subjects hospitalised with a CF pulmonary exacerbation in a pilot retrospective non-randomised study. They found that that HTS is well tolerated during treatment of a CF pulmonary exacerbation but offers no clear outcome benefits.

Although the design of this study would be unacceptable to Cochrane reviewers it is quite useful information showing that, in the experience of these authors, the addition of HTS to their usual treatment regimen for treating pulmonary exacerbations was not helpful – although clinicians may wish try the addition of HTS for individual patients where progress was less than expected.

2012 Rosenfeld M. Ratjen F. Brumback L. Daniel S. Rowbotham R. McNamara S. Johnson R. Kronmal R. Davis SD. ISIS Study Group. Inhaled hypertonic saline in infants and children younger than 6 years with cystic fibrosis: the ISIS randomized controlled trial. JAMA 2012; 307:2269-77. [PubMed]
To determine if hypertonic saline reduces the rate of protocol-defined pulmonary exacerbations in patients younger than 6 years with CF.

The Infant Study of Inhaled Saline in Cystic Fibrosis (ISIS), a multicenter, randomized, double-blind, placebo-controlled trial conducted from April 2009 to October 2011 at 30 CF care centers in the United States and Canada. Participants were aged 4 to 60 months and had an established diagnosis of CF. A total of 344 patients were assessed for eligibility; 321 participants were randomized; 29 (9%) withdrew prematurely. The active treatment group (n = 158) received 7% hypertonic saline and the control group (n = 163) received 0.9% isotonic saline, nebulized twice daily for 48 weeks. Both groups received albuterol or levalbuterol prior to each study drug dose. Rate during the 48-week treatment period of protocol-defined pulmonary exacerbations treated with oral, inhaled, or intravenous antibiotics.

The mean pulmonary exacerbation rate (events per person-year) was 2.3 (95% CI, 2.0-2.5) in the active treatment group and 2.3 (95% CI, 2.1-2.6) in the control group; the adjusted rate ratio was 0.98 (95% CI, 0.84-1.15). Among participants with pulmonary exacerbations, the mean number of total antibiotic treatment days for a pulmonary exacerbation was 60 (95% CI, 49-70) in the active treatment group and 52 (95% CI, 43-61) in the control group. There was no significant difference in secondary end points including height, weight, respiratory rate, oxygen saturation, cough, or respiratory symptom scores. Infant pulmonary function testing performed as an exploratory outcome in a subgroup (n = 73, with acceptable measurements at 2 visits in 45 participants) did not demonstrate significant differences between groups except for the mean change in forced expiratory volume in 0.5 seconds, which was 38 mL (95% CI, 1-76) greater in the active treatment group. Adherence determined by returned study drug ampoules was at least 75% in each group. Adverse event profiles were also similar, with the most common adverse event of moderate or severe severity in each group being cough (39% of active treatment group, 38% of control group).

This was a major trial which showed among infants and children younger than 6 years with cystic fibrosis, the use of inhaled hypertonic saline compared with isotonic saline did not reduce the rate of pulmonary exacerbations over the course of 48 weeks of treatment.

2013 Subbarao P. Stanojevic S. Brown M. Jensen R. Rosenfeld M. Davis S. Brumback L. Gustafsson P. Ratjen F. Lung clearance index as an outcome measure for clinical trials in young children with cystic fibrosis. A pilot study using inhaled hypertonic saline. Am J Respir Crit Care 2013; 188:456-60. [PubMed]
Lung clearance index (LCI), measured by multiple breath washout (MBW), is a noninvasive measure of ventilation inhomogeneity that holds promise as an objective physiologic endpoint for clinical trials in infants and preschool children with cystic fibrosis (CF).OBJECTIVES: To study the feasibility of using LCI to assess treatment effect outcomes in CF trials of infants and preschoolers.METHODS: The Infant Study of Inhaled Saline trial was a multicenter, randomized, controlled trial of hypertonic (7%) versus isotonic (0.9%) saline inhaled twice daily for 48 weeks in children with CF under 6 years of age. LCI measurements were performed in a single-center pilot substudy at baseline and 48 weeks using a respiratory mass spectrometer and sulfur hexafluoride as the tracer gas. LCI measurements were standardized using published normative data (zLCI) to account for height-related changes in LCI during early childhood. A generalized estimating equation model with an interaction between treatment group and test occasion was used to estimate a treatment effect.
MEASUREMENTS AND MAIN RESULTS: A total of 27 participants were randomized; 25 participants, aged (median [range]) 2.6 (0.34-4.95) years, had acceptable baseline and follow-up LCI measures. On average, LCI decreased in the hypertonic saline group (n = 12) by 1.19 z-scores units (95% confidence interval [CI] = -2.46 to 0.06), and remained stable in the isotonic saline group (n = 13) at 0.81 (95% CI = -0.40 to 2.02). A significant treatment effect was observed for zLCI (2.01; 95% CI = 0.26 to 3.76; P = 0.025).

The authors showed that multiple breath washout testing is feasible in an interventional study in infants and preschool children with CF. These pilot findings support the development of MBW and LCI as an objective outcome measure in interventional trials in young children with CF, and provide estimates for sample size calculations for future studies.

2014 Michon Anne-Laure, Jumas-Bilaket E, Chiron R, Lamy B, Marchandin H. Advances toward the Elucidation of Hypertonic Saline Effects on Pseudomonas aeruginosa from Cystic Fibrosis Patients. PLoS One 2014;9:e90164; free full text at
Nebulized hypertonic saline (HTS) has beneficial effects including reducing pulmonary exacerbations in Cystic Fibrosis (CF) patients. Several mechanisms may explain these effects but antimicrobial activity of NaCl remains largely unexplored. The study aimed to measure the antimicrobial effect of NaCl on Pseudomonas aeruginosa isolated from the respiratory tract in CF patients.
it was found that NaCl inhibited the growth of all isolates and killed 38% of tested isolates within concentration range currently used in therapeutics.

–   The results suggest that anti-pseudomonal activity is another mechanism of action of HTS to add to those already established. The authors noted that further studies are needed to determine the ideal NaCl volume, frequency of administration and mode of administration to optimise the potential bactericidal effects of hypertonic saline therapy in CF.

2016 Dentice RL; Elkins MR; Middleton PG; Bishop JR; Wark PA; Dorahy DJ; Harmer CJ; Hu H; Bye PT.  A randomised trial of hypertonic saline during hospitalisation for exacerbation of cystic fibrosis. Thorax. 71(2):141-7, 2016 Feb. [PubMed]
To determine the effects of hypertonic saline inhalation during hospitalisation for exacerbation of CF. 132 adults with an exacerbation of CF were randomised to inhale three nebulised doses a day of either 4 mL 7% saline or a taste-masked control of 0.12% saline, throughout the hospital admission. The primary outcome measure was length of hospital stay.The authors concluded the addition of hypertonic saline to the management of a CF exacerbation did not reduce the length of hospital stay but hypertonic saline speeds the resolution of exacerbation symptoms and allows patients to leave hospital with greater symptom resolution.

– The authors do not state whether they have adopted the use of hypertonic saline as part of their regime for treating pulmonary exacerbations; they suggest that other centres should examine the possibility.

Scott H Donaldson T Danielle SamulskiCaroline LaFaveKirby ZemanJihong WuAaron TrimbleAgathe CeppeWilliam D BennettStephanie D Davis.  A four-week trial of hypertonic saline in children with mild cystic fibrosis lung disease: Effect on mucociliary clearance and clinical outcomes.  J Cyst Fibros  2020 Jul 12;S1569-1993(20)30801-8.doi: 10.1016/j.jcf.2020.07.009.Online ahead of print. [Pubmed]

Scott H Donaldson

Hypertonic saline (HS) is commonly prescribed for children with cystic fibrosis (CF) despite the absence of strong data indicating clinical efficacy in a population with mild lung disease. We hypothesized that HS treatment would result in a sustained improvement in mucociliary clearance (MCC) in children with CF who had minimal lung disease, thus providing evidence for a biologically relevant effect that also may be associated with clinical improvements.
The authors performed a randomized, placebo controlled, double blind study of 6% versus 0.12% sodium chloride, delivered three-times daily with an eFlow nebulizer for 4 weeks. MCC was measured using gamma scintigraphy at baseline, 2-hours after the first study treatment, and ~12-hours after the final dose (at day 28). Spirometry, respiratory symptoms (CFQ-R), and safety were also assessed.
Results: Study treatments were generally well tolerated and safe. HS (6% sodium chloride) resulted in a significant, sustained improvement from baseline in whole lung clearance after 4 weeks of therapy (p = 0.014), despite absence of a prolonged single-dose effect after the initial dose. This sustained change (12 hrs after prior dose) was significantly greater when compared to placebo (0.12% sodium chloride) treatment (p = 0.016). Improvements in spirometry with HS did not reach statistical significance but correlated with MCC changes
Conclusions: The observed sustained improvement in MCC with HS suggests that this treatment may yield health benefits, even in relatively mildly affected children with CF. Highlighting this physiologic finding is important due to the lack of meaningful, validated endpoints in this population.

Dr Scott Donaldson is at the University of North Carolina School of Medicine, Chapel Hill.

Stahl MWielpütz MORicklefs IDopfer CBarth SSchlegtendal AGraeber SYSommerburg ODiekmann G, Hüsing JKoerner-Rettberg CNährlich LDittrich AMKopp MVMall MA.Preventive Inhalation of Hypertonic Saline in Infants with Cystic Fibrosis (PRESIS): A Randomized, Double-Blind, Controlled Study.Am J Respir Crit Care Med. 2018 Nov 9. doi: 10.1164/rccm.201807-1203OC. [Epub ahead of print]  [Pubmed]

Mirjam Stahl

Cystic fibrosis (CF) lung disease starts in early infancy suggesting that preventive treatment may be most beneficial. Lung clearance index (LCI) and chest magnetic resonance imaging (MRI) have emerged as promising endpoints of early CF lung disease, however, randomized controlled trials testing the safety and efficacy of preventive therapies in infants with CF are lacking.   This study was to determine feasibility, safety and efficacy of preventive inhalation with hypertonic saline (HS) compared to isotonic saline (IS) in infants with CF including LCI and MRI as outcome measures.

In this randomized, double-blind, controlled trial 42 infants with CF less than 4 months of age were randomized across 5 sites to twice daily inhalation of 6% HS (n=21) or 0.9% IS (n=21) for 52 weeks. Inhalation of HS and IS was generally well tolerated by CF infants and the number of adverse events did not differ between groups (P=0.49). The change in LCI from baseline to week 52 was larger in CF infants treated with HS (-0.6) compared to IS (-0.1, P<0.05). In addition, weight gain was improved in CF infants treated with HS (P<0.05), whereas pulmonary exacerbations and chest MRI scores did not differ in the HS vs. IS group.

The authors concluded preventive inhalation with HS initiated in the first months of life was safe and well tolerated, and resulted in improvements in LCI and weight gain in infants with CF. Their  results support feasibility of LCI as endpoint in randomized controlled trials in infants with CF..

Dr M Stahl from the Division of Pediatric Pulmonology & Allergy and Cystic Fibrosis Centre, Department of Pediatrics and Department of Translational Pulmonology, Translational Lung Research Centre Heidelberg (TLRC).

Trimble ATWhitney Brown ALaube BLLechtzin NZeman KLWu JCeppe AWaltz DBennett WDDonaldson SH. Hypertonic saline has a prolonged effect on mucociliary clearance in adults with cystic fibrosis. J Cyst Fibros. 2018 Jan 19. pii: S1569-1993(18)30004-3. doi: 10.1016/j.jcf.2018.01.001. [Epub ahead of print]  [Pubmed]

     Aaron Trimble

In a large study of young children with CF inhaled hypertonic saline (HS) failed to demonstrate clinical benefits. These authors previously reported the absence of a sustained effect of HS on mucociliary clearance (MCC) in healthy adults and in this study sought to characterize the durability of the MCC response to HS in adults with CF using gamma scintigraphy

Elkins MDentice R.  Timing of hypertonic saline inhalation for cystic fibrosis.
Cochrane Database Syst Rev.
 2020 Feb 28;2:CD008816. doi: 10.1002/14651858.CD008816.pub4. [Pubmed]

             Mark Elkins

Inhalation of hypertonic saline improves sputum rheology, accelerates mucociliary clearance and improves clinical outcomes of people with cystic fibrosis. This is an update of a previously published Cochrane Review.

The authors concluded timing of hypertonic saline inhalation makes little or no difference to lung function (low-certainty evidence). However, inhaling hypertonic saline before or during airway clearance techniques may maximise perceived efficacy and satisfaction. The long-term efficacy of hypertonic saline has only been established for twice-daily inhalations; however, if only one dose per day is tolerated, the time of day at which it is inhaled could be based on convenience or tolerability until evidence comparing these regimens is available.

Dr Mark Elkins is Clinical Associate Professor in the University of Sydney, Sydney Medical School and Senior research physiotherapist at the Royal Prince Albert Hospital, Sydney.

The authors showed that, in contrast to healthy adults, a single dose of HS has a prolonged effect on MCC in adults with CF, which lasts at least 4 h. This may explain its clinical efficacy in this population.

Dr. Aaron Trimble is a pulmonologist in Chapel Hill,  North Carolina, and affiliated with the University of North Carolina.

Vito TerlizziLaura ClautAntonella ToscoCarla ColomboValeria RaiaBenedetta Fabrizzi, et al. A survey of the prevalence, management and outcome of infants with an inconclusive diagnosis following newborn bloodspot screening for cystic fibrosis (CRMS/CFSPID) in six Italian centres. J Cyst Fibros 2021 Apr 18;S1569-1993(21)00097-7. doi: 10.1016/j.jcf.2021.03.015.Online ahead of print. [Pubmed]

     Vito Terlizzi

Objective:We evaluated the prevalence, Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene profile, clinical data, management and outcome for infants with a CFTR-related metabolic syndrome/CF Screen Positive, Inconclusive Diagnosis (CRMS/CFSPID) designation from six Italian centres.
Methods:All newborn bloodspot screening (NBS) positive infants born from January 2011 to August 2018 with a CF diagnosis or a CRMS/CFSPID designation were enrolled. Data on sweat testing, genetics, clinical course and management were collected.
Results:We enrolled 257 CF patientsand 336 infants with a CRMS/CFSPID designation (CF: CRMS/CFSPID ratio of 1:1.30).Blood immuno-reactive trypsinogen (IRT) was significantly lower in CRMS/CFSPID infants and the F508del variant accounted for only 20% of alleles. Children with CRMS/CFSPID showed a milder clinical course, pancreatic sufficiency compared to CF infants. Varied practice across centres was identified regarding sweat testing, chest radiograph (8-100%) and salt supplementation (11-90%). Eighteen (5.3%) CRMS/CFSPID infants converted or were reclassified to diagnosis of CF. Four infants (1.3%) developed a clinical feature consistent with a CFTR-related disorder (1.2%). Twenty-seven were re-classified as healthy carriers (8.0%) and 16 as healthy infants (4.8%).
Conclusions:We have identified considerable variability in the evaluation and management of infants with an inconclusive diagnosis following NBS across six Italian centres. CRMS/CFSPID is more regularly seen in this population compared to countries with higher prevalence of F508del.Conversion to a CF diagnosis was recorded in 18 (5.3%) of CRMS/CFSPID infants and in 16 was as a result of increasing sweat chloride concentration.

Dr Vito Terlizzi is at the Cystic Fibrosis Regional Reference Center, Department of Paediatric Medicine, Anna Meyer Children’s University, Florence, Italy.

Christopher H GossIsabelle FajacRaksha Jain 3Wolfgang Seibold Abhya Gupta Ming-Chi Hsu Sivagurunathan SutharsanJane C Davies Marcus A Mall. Efficacy and safety of inhaled ENaC inhibitor BI 1265162 in patients with cystic fibrosis: BALANCE-CF™ 1 – a randomised, Phase II study   [Pubmed]

Christopher H Goss

Background: Inhibition of the epithelial sodium channel (ENaC) in cystic fibrosis (CF) airways provides a mutation-agnostic approach that could improve mucociliary clearance in all CF patients. BI 1265162 is an ENaC inhibitor with demonstrated preclinical efficacy and safety already demonstrated in humans.
Objective: We present results from BALANCE-CF™ 1, a Phase II, placebo-controlled, randomised, double-blind study of four dose levels of BI 1265162 versus placebo for 4 weeks on top of standard of care in adults and adolescents with CF.
Results: Initially, 28 randomised subjects (n=14 each BI 1265162 200 µg BID, placebo BID) were assessed at an interim futility analysis. Compared with placebo, numerical changes of -0.8% (95%CI -6.6, 4.9) in ppFEV1 and +2.1 units (95%CI -2.4, 6.5) in LCI were observed in the active group, meeting a predefined stopping rule; accordingly, the study was terminated. Recruitment had continued during the interim analysis and pending results; 24 patients were added across three dose levels and placebo. The final results including these patients (+1.5% ppFEV1, 200 µg BID dose versus placebo) were not supportive of relevant clinical effect. LCI change was also not supportive, although interpretation was limited due to insufficient traces meeting quality criteria. A 9.4-point improvement in CFQ-R Respiratory Domain was observed in the 200 µg BID dose group versus placebo. BI 1265162 up to 200 µg BID was safe and well-tolerated. Pharmacokinetics were similar to those in healthy volunteers.
Conclusion: BI 1265162 was safe but did not demonstrate a potential for clinical benefit. Development has been terminated.

Dr Christopher H Goss is Professor at Department of Medicine, Department of Pediatrics, University of Washington; Seattle Children’s Hospital & Research Institute, Seattle, WA, USA


Pulmozyme has proved to be one of the most successful therapies introduced during the past 20 years. It is widely used for CF and many other respiratory conditions (now some 359 references on Medline – 265 concerning cystic fibrosis).  By 2012 Pulmozyme was taken by 83.7% patients on the US CF Foundation registry who were over 6 years old and almost half those on the UK Patient registry; eventually it would be used earlier and by milder affected and younger patients.

1990 Shak S, Capon DJ, Hellmiss R, Marsters SA, Baker CL. Recombinant human DNase 1 reduces the viscosity of cystic fibrosis sputum. Proc Natl Acad Sci 1990; 87:9188-9192.[PubMed]

      Steve Shack

An early report of the significant effect of recombinant human DNase1 (Pulmozyme) on sputum viscosity in people with CF by Dr Steve Shak (figure 4). To evaluate the potential clinical utility of recombinant human DNase I (rhDNase) in the treatment of CF, the authors cloned, sequenced, and expressed rhDNase. Catalytic amounts of rhDNase greatly reduced the viscosity of purulent CF sputum, transforming it within minutes from a non-flowing viscous gel to a flowing liquid. The reduction in viscosity is associated with a decrease in size of the DNA in the sputum. The authors suggested that inhalation of an rhDNase aerosol may be a simple direct approach that would help individuals with CF, and other patients with pneumonia or bronchitis, to clear their airways of purulent secretions.

In 1950 Armstrong JB & White JC (Lancet 1950; 2:739-742. [PubMed]) had shown that bovine pancreatic DNase1, added to viscid purulent sputum, destroyed the extra cellular fibres of DNA and reduced the viscosity.

Later Elmes PC & Armstrong JB (Thorax 1953; 8:295-300.[PubMed]) reported its use in chronic bronchitis, but the side effects of the bovine preparation eventually precluded its use and further development at that time (Raskin P. Am Rev Respir Dis 1968; 98:697-698.[PubMed]).

Subsequently the rhDNase (Pulmozyme) reported here proved to be one of, if not the, major therapeutic advance of the Nineties.

1993 Ranasinha C, Assoufi B, Shak S, Christiansen D, Fuchs H, Empey D, Geddes D, Hodson M. Efficacy and s1afety of short-term administration of aerosolised recombinant human DNase I in adults with stable stage cystic fibrosis. Lancet 1993; 342:199-202. [PubMed]
A trial of DNase (Pulmozyme) from the Brompton Hospital, London, in which the mean percentage change in FEV1 from baseline was a 13.3% rise on rhDNase and only a 0.2% fall on placebo (p < 0.001). There was an insignificant rise of FVC of 7.2% in the rhDNase group and 2.3% in the placebo group.

This study provided further confirmation that short-term administration of rhDNase in stable patients with cystic fibrosis was safe and resulted in an impressive improvement in lung function (also Shak et al, 1990 above; Fuchs et al. 1994 below).

1994 Fuchs HJ, Borowitz DS, Christiansen DH, Morris EM, Nash ML, Ramsey BW, Rosenstein BJ, Smith AL, Wohl ME. Effect of aerosolized recombinant human DNase on exacerbations of respiratory symptoms and on pulmonary function in patients with cystic fibrosis. The Pulmozyme Study Group. N Engl J Med 1994; 331:637-642[PubMed]

      Henry Fuchs

Dr Henry J Fuchs,(figure) while working at Genentech from 1987 to 1996, led the clinical programme that resulted in the approval of Pulmozyme – one of the major clinical advances introduced during the Nineties. Dr Fuchs is now Senior Vice President and Chief Medical Officer of Biomarin.

This report, the main publication on rhDNase (Pulmozyme), describes a randomized, double-blind, placebo- controlled study to determine the effects of once-daily and twice- daily administration of rhDNase on frequency of exacerbations of respiratory symptoms requiring parenteral antibiotics and on pulmonary function.

A total of 968 adults and children with cystic fibrosis were treated for 24 weeks as outpatients. As compared with placebo, the administration of rhDNase once daily and twice daily reduced the age-adjusted risk of respiratory exacerbations by 28 percent (P = 0.04) and 37 percent (P < 0.01), respectively. The administration of rhDNase once daily and twice daily improved forced expiratory volume in one second during the study by a mean (+/- SD) of 5.8 +/- 0.7 and 5.6 +/- 0.7 percent, respectively. Transient voice alteration and laryngitis were more frequent in the rhDNase-treated patients.

This was the definitive Phase III trial showing the significant effect of inhaled rhDNase – one of the most important large multicentre studies of the 1990s. Pulmozyme was undoubtedly one of the major clinical advances of the decade and was licensed by the FDA in 1994 following this study. Regular treatment with DNase would become widely used – by 2010 used by 78.4% patients on the US CF Foundation registry and 42.7% of those on the UK Patient registry; eventually it would be used earlier and by milder affected and younger patients (Quann et al, 2001 below) and eventually, in some CF units for infants. The cost (approximately £7000 per year) proved a problem in certain parts of the UK. (Also Shak et al, 1990 above; Ranasinha et al, 1993 above)

2001 Suri R, Metcalfe C, Lees B, Grieve R, Flather M, Normand C, Thompson S, Bush A, Wallis C. Comparison of hypertonic saline and alternate day or daily recombinant human deoxyribonuclease in children with cystic fibrosis: a randomised trial. Lancet 2001; 358:1316-1321. [PubMed]
In an open cross-over trial, 48 children were allocated in random order to 12 weeks of once-daily rhDNase (2.5 mg), alternate-day rhDNase (2.5 mg), and twice-daily 5 ml 7% hypertonic saline. The primary outcome was FEV1. The mean FEV1 increased by 16% (SD 25%), 14% (22%), and 3% (21%) with daily rhDNase, alternate-day rhDNase, and hypertonic saline, respectively. There was no difference between daily and alternate-day rhDNase. However, daily rhDNase showed a significantly greater increase in FEV1 than hypertonic saline (8% {2 to 14}, p=0.01).

It is no surprise that hypertonic saline, delivered by jet nebuliser, was not as effective as daily rhDNase, although there was variation in individual response. Interestingly there was no evidence of a difference between daily and alternate-day rhDNase. Although inhaled hypertonic saline was less effective as a mucolytic than rhDNase, it was considerably cheaper. It must be stressed that these are group responses and there is considerable individual variation between patients and it is important that clinicians assess the individual response of each patient when prescribing these treatments. Also it was later shown failure to respond to rhDNase may be related to the magnesium status of the patient (Sanders NN et al, Thorax 2006; 61:962-968. [PubMed]).

2001 Quan JM, Tiddens HAWM, Sy JP, McKenzie SG, Montgomery MD, Robinson PJ, Wohl ME, Konstan MW. Pulmozyme Early Intervention Trial Study Group. A two-year randomised placebo controlled trial of dornase alfa in young patients with cystic fibrosis with mild lung function abnormalities. J Pediatr 2001; 139:813-820. [PubMed]
This was a 96-week, randomized, double-blind, placebo-controlled trial involving 49 CF centers and 474 children. Inclusion criteria were age six to 10 years and forced vital capacity > or = 85% predicted. At 96 weeks the treated group had maintained their respiratory function levels; the treatment benefit for dornase alfa compared with placebo in percent predicted (mean +/- SE) was 3.2 +/- 1.2 for FEV1 (P =.006), 7.9 +/- 2.3 for FEF 25-75 % (P =.0008), and 0.7 +/- 1.0 for FVC (P =.51). The risk of respiratory tract exacerbation was reduced by 34% in patients who received dornase alfa. The authors concluded that treatment of young patients with CF with dornase alfa maintains lung function and reduces the risk of exacerbations over a 96-week period.

–   The results of this trial influenced some paediatricians to try young CF patients on Pulmozyme before they developed chronic infection and this became routine practice in at least one large UK Paediatric CF Centre and also in Copenhagen where the treatment was found to reduce the frequency of respiratory exacerbations and new positive respiratory tract cultures (Frederiksen et al, 2006 below).

2002 Ballmann M, von der Hardt H. Hypertonic saline and recombinant human DNase: a randomised cross-over pilot study in patients with cystic fibrosis. J Cyst Fibros 2002; 1:35-37). [PubMed]
The first evidence that there was a comparable increase in FEV1 with rhDNase and hypertonic saline. The authors commented that a larger study was required to confirm these findings.
This has not been the general experience – usually rhDNase appears to be the more effective.

2003 Berge MT, Wiel E, Tiddens HA, Merkus PJ, Hop WC, de Jongste JC. DNase in stable cystic fibrosis infants: a pilot study. J Cyst Fibros 2003; 2:183-188. [PubMed] The authors treated nine CF patients (0.7-1.9 years) with nebulised rhDNase (2.5 mg) and NaCl 0.9% (10 ml) via jet nebulizer cross-over once daily during 2-week treatment blocks. Measurements were performed at baseline and after treatment blocks and consisted of lung function tests (plethysmography and tidal rapid thoraco-abdominal compression technique), overnight pulse oximetry, and daily symptom scores. The DNase treatment and the different assessments were well tolerated by all children and their parents. Lung function showed increased airway patency after treatment with rhDNase (P < 0.001), but not after NaCl 0.9%. This pilot study indicates that objective assessment of the effects of rhDNase is feasible in infants with CF who have little or no respiratory symptoms. They considered these results warrant a larger randomized placebo-controlled trial.

–   This small but detailed study from an expert unit showed definite short term benefit from inhaled rhDNase even in infants. At least one large paediatric centre in the UK tries CF infants on rhDNase as soon as they are able to inhale it.

2005 Fitzgerald DA, Hilton J, Jepson B, Smith L. A crossover, randomized, controlled trial of dornase alfa before versus after physiotherapy in cystic fibrosis. Pediatrics 2005; 116:e549-554. [PubMed]
This trial showed that Dornase alfa is equally efficacious when delivered before or after physiotherapy/PEP in patients with CF. However, patients who are infected persistently with P. aeruginosa may derive more improvement in FEV1 when dornase alfa is delivered after physiotherapy/PEP.

2005 Robinson TE, Goris ML, Zhu HJ, Chen X, Bhise P, Sheikh F, Moss RB. Dornase alfa reduces air trapping in children with mild cystic fibrosis lung disease: a quantitative analysis. Chest 2005; 128:2327-35. [PubMed]
Twenty-five children with CF randomized to either daily rhDNase or placebo aerosol were evaluated at baseline, and at 3 and 12 months by spirometer-triggered HRCT and spirometry. After 3 months of treatment, both groups had improvements in percentage of predicted FEV1 and FEF(25-75%), and total HRCT visual scores. In contrast, the rhDNase group had a 13% decrease in quantitative air trapping from baseline (severe air trapping [A3]), compared to an increase of 48% in the placebo group (p = 0.023). Quantitative air trapping (A3) remained improved in the rhDNase group (- 15.4%) and worsened in the placebo group (+61.3%) with nearly significant differences noted between groups (p = 0.053) after 12 months of treatment.

The authors concluded quantitative air trapping is a more consistent sensitive outcome measure than either spirometry or total HRCT scores, and can discriminate differences in treatment effects in children with minimal CF lung disease.

–   One of the earliest signs of CF is air trapping and over inflation on the chest X-ray. It would be reasonable to expect this to improve with rhDNase treatment. Indeed many paediatricians are now trying young children on rhDNase as soon as they are able to take it.

2006 Sanders NN, Franckx H, De Boeck K, Haustraete J, De Smedt SC, Demeester J. Role of magnesium in the failure of rhDNase therapy in patients with cystic fibrosis. Thorax 2006; 61:962-968. [PubMed]
rhDNase (Pulmozyme) is a major component of treatment for people with CF but some patients show no or little response and hence fail to benefit from this important drug. In this study the biochemical properties, physical properties, and degradation by rhDNase-I of sputum obtained from clinical responders and non-responders were compared; also the ability of magnesium to reactivate rhDNase-I in DNA solutions and in sputum was investigated.

The effect of oral magnesium supplements on magnesium levels in the sputum of patients with CF was also examined. Sputum from clinical responders was extensively degraded in vitro on incubation with rhDNase-I, while sputum from clinical non-responders was not degraded: the median decrease in sputum elasticity in the two groups was 32% and 5%, respectively.
Sputum from clinical responders contained significantly higher concentrations of magnesium than sputum from non-responders (2.0 mM v 1.3 mM; p = 0.020). Sputum that could not be degraded by rhDNase-I became degradable after preincubation with magnesium. The effect of magnesium on rhDNase-I activity was mediated through actin. Oral intake of magnesium enhanced the magnesium concentration in the sputum of CF patients.

So increasing the magnesium concentration in sputum by, for example, oral magnesium supplements may be a promising strategy to overcome the failure of rhDNase-I in some patients with CF.

One further supportive study by Rosenecker J et al. (Airway surface liquid contains endogenous DNase activity which can be activated by exogenous magnesium. Eur J Med Res 2009; 14:304-308. [PubMed]). They found BAL samples degraded plasmid DNA only after pre-incubation with magnesium. When analyzing the exhaled breath condensate the samples obtained from the healthy volunteers showed no DNase activity even after pre incubation with magnesium, whereas in one of the two samples obtained from CF patients contained DNase activity after pre-incubation with magnesium. The authors concluded that increasing the magnesium concentration in the airway surface liquid by aerosolisation of magnesium solutions or oral magnesium supplements could improve the removal of highly viscous mucus in chronic lung disease by activating endogenous DNase activity.

Professor Kris De Boeck of University Hospital Leuven, Belgium is a leading, very active researcher and clinician in the CF field. Potentially a very useful paper which could benefit the 30-50% of patients who fail to show a significant response to rhDNase.

2006 Frederiksen B, Pressler T, Hansen A, Koch C, Hoiby N. Effect of aerosolized rhDNase (Pulmozyme) on pulmonary colonization in patients with cystic fibrosis. Acta Paediatr 2006; 95:1070-1074. [PubMed]
During one year patients with CF were randomized either to aerosolized Pulmozyme daily or to no Pulmozyme. The number of positive respiratory cultures was higher in the untreated group (82%) compared with the treated group (72%) (p<0.05). The most striking difference was found for Staphylococcus aureus, with a prevalence of 30% in the untreated group compared with 16% in the treated group (p<0.0001). Pulmonary function (FEV1) in the treated group showed a significant increase of 7.3% compared to 0.9% in the untreated group (p<0.05). Long term DNase treatment was beneficial to CF patients without chronic lower respiratory tract infection, with fewer positive respiratory cultures, leading to reduced demand for antibiotics and to improved lung function.

–   A useful study from Copenhagen showing inhaled rhDNase reduced the likelihood of a positive respiratory culture – admittedly a rather modest effect. This finding provides additional support for starting all patients on the treatment at an early age, where inhaled treatment is practical, as occurs now in some centres.

2007 McKenzie SG, Chowdhury S, Strandvik B, Hodson ME. Investigators of the Epidemiologic Registry of Cystic Fibrosis. Dornase alfa is well tolerated: data from the epidemiologic registry of cystic fibrosis. Pediatr Pulmonol 2007; 42:928-937. [PubMed]

     Sheila McKenzie

After closure of the Epidemiologic Registry of Cystic Fibrosis, a comprehensive safety analysis of dornase alfa (Pulmozyme) was performed. The results confirm the safety of dornase alfa in people with CF of all ages. Children under 5 years old appear to tolerate dornase alfa at least as well as older patients.

There is an accumulating literature on the use of rhDNase in people with CF and most is favourable, confirming its beneficial effect and safety. In one large CF unit in the UK all children are given a trial on rhDNase as soon as inhalation therapy becomes feasible. Undoubtedly rhDNase is one of the more important treatment advances of the past 15 years (Shak et al, 1990 above; Fuchs et al, 1994 above).

Dr Sheila McKenzie (figure) of Hoffmann-La Roche ltd, has been involved with the development and introduction of Pulmozyme since the first clinical trials in the Nineties shortly after Pulmozyme was licensed. She was involved in the latter stages of the European phase IIIb study (published in 1998), the implementation (but not the original planning) of ERCF and the planning & implementation of the Quan mild patient study. Shiela is the longest-serving member of Roche & Genentech staff to have worked with CF; she retired in 2012.

2008 McLaughlin AM, McGrath E, Barry R, Egan JJ, Gallagher CG. Treatment of lobar atelectasis with bronchoscopically administered recombinant human deoxyribonuclease in cystic fibrosis? Clin Respir J 2008; 2:123-126. [PubMed]
The objective of this study was to describe experience in which rhDNase (Pulmozyme) was administered by bronchoscopic instillation into atelectatic lobes in five adults with CF. This method was successful in treating lobar atelectasis, which was resistant to conventional therapy with antibiotics and physiotherapy. In all but one of the cases described, administration of DNase in this manner resulted in a radiographic and clinical improvement of the atelectasis. The authors recommend that respiratory physicians consider this as a second line treatment in the management of atelectasis.

–   Although not the first to use this treatment for atelectasis, further confirmation of the success of this treatment is useful for clinicians faced with resistant atelectasis.

2008 Padman R, Werk LN, Ramirez-Garnica G, Ye G, Nathanson I. Association between practice patterns and body mass index percentile in infants and young children with cystic fibrosis. J Cyst Fibros 2008; 7:385-390.[PubMed].
Data from the CF Registry on 165 infants who were using Pulmozyme before the age of 2 years suggested that this early use of dornase alpha may improve nutritional outcome through age six.

2009 Rosenecker J, Naundorf S, Rudolph C. Airway surface liquid contains endogenous DNase activity which can be activated by exogenous magnesium. Eur J Med Res 2009; 14:304-308. [PubMed].
Increasing the magnesium concentration in the airway surface liquid by aerosolisation of magnesium solutions or oral magnesium supplements could improve the removal of highly viscous mucus in chronic lung disease by activating endogenous DNase activity

–   An interesting observation as magnesium had already been involved in failure of DNase therapy in people with CF (Sanders NN et al. 2006.[PubMed]).

2010 Minasian C, Wallis C, Metcalfe C, Bush A. Comparison of inhaled mannitol, daily rhDNase and a combination of both in children with cystic fibrosis: a randomised trial. Thorax 2010; 65:51-56. [PubMed]
Osmotic agents, such as inhaled dry powder mannitol, may increase mucociliary clearance by rehydrating the airway surface liquid and thus act as disease-modifying treatments in cystic fibrosis (CF). This is the first therapeutic trial of inhaled mannitol in children with CF; it was compared with recombinant human deoxyribonuclease (rhDNase), the current best established mucolytic treatment. METHODS: 38 children were recruited to an open crossover study. Subjects underwent an initial bronchial provocation challenge with dry powder mannitol. Those children with a negative challenge were randomly allocated to one of three consecutive 12-week treatment blocks (inhaled mannitol alone, nebulised rhDNase alone and mannitol + rhDNase). The primary outcome was forced expiratory volume in 1 s (FEV(1)). A number of secondary outcome measures were also studied. RESULTS: Only twenty children completed the study. Bronchoconstriction and cough associated with mannitol administration contributed to the high attrition rate. The mean increase in FEV(1) following 12 weeks of treatment was 0. 11 litres (6. 7%) (p = 0. 055) for mannitol alone, 0. 12 litres (7. 2%) (p = 0. 03) for rhDNase alone and 0. 03 litres (1. 88%) (p = 0. 67) for rhDNase and mannitol. None of the secondary clinical outcomes was statistically significantly different between treatments.

The authors concluded that inhaled mannitol was at least as effective as rhDNase after 3 months treatment. There was a marked individual variation in tolerance to mannitol and in response to treatment however. Children who do not respond to rhDNase may benefit from a trial of inhaled mannitol. The combination of mannitol and rhDNase was not useful. A very useful study for those managing patients with CF.

2011 Konstan MW, Wagener JS, Pasta DJ, Millar SJ, Jacobs JR, Yegin A, Morgan WJ. Scientific Advisory Group and Investigators and Coordinators of Epidemiologic Study of Cystic Fibrosis. Clinical use of dornase alpha is associated with a slower rate of FEV1 decline in cystic fibrosis. Pediatr Pulmonol 2011; 46:545-553.[PubMed]
Randomized controlled trials of dornase alpha (Pulmozyme) have shown forced expiratory volume in 1 sec (FEV1 ) to improve in patients with cystic fibrosis (CF) but have not assessed change in the rate of lung function decline. The authors assessed the relationship of dornase alpha use and FEV1 decline using the Epidemiologic Study of Cystic Fibrosis (ESCF).

The dornase alpha group (n = 2,230) had a lower FEV1 % predicted at index and a more rapid decline during the pre-index period. The mean rate of FEV1 decline improved for the dornase alpha group; the improvement was similar in adults and children 8-17 years old but was not statistically significant in adults. The comparator group (n = 5,970) showed no change among adults and an increased rate of decline among children 8-17 years old. The authors concluded the use of dornase alpha for a 2-year period is associated with a reduction in the rate of FEV1 decline.

The authors observe that these results demonstrate the value of using an observational study to assess the association of instituting new therapies in the clinical setting with changes in the rate of FEV1 decline in patients with CF. There is increasing data to show that the newer interventions are having long term benefit as well as significant effects in the clinical trials.

2012 Konstan MW, Ratjen F. Effect of dornase alfa on inflammation and lung function: potential role in the early treatment of cystic fibrosis. J Cyst Fibros 2012; 11:78-83.[PubMed]
Observational studies indicate that dornase alfa is often reserved for “sicker” patients. A 2-year, early intervention study of dornase alfa in CF patients with early lung disease demonstrated significant improvements in lung function and risk of exacerbation compared to placebo. A more recent analysis, using the database of the large observational Epidemiologic Study of Cystic Fibrosis (ESCF), found that initiation of dornase alfa has the potential to alter the course of CF by decreasing the rate of lung function decline in children and adults. These encouraging results, possibly linked to indirect effects on inflammation, suggest a greater role for dornase alfa therapy in the early treatment of CF, where it may help preserve lung function and potentially extend survival.

Felix Ratjen and Michael Konstan review the compelling reasons for starting early Pulmozyme rather than waiting until the infection is more advanced. Many UK paediatricians are now (in 2014) starting Pulmozyme in very small children with CF as all studies of young infants either by respiratory function or bronchoscopy indicate of the very early onset of bronchial abnormalities. Presumably, as most clinicians do not have access to infant respiratory function tests, the response is judged by clinical signs – often by a reduction in wheezing, cough or hyperinflation.

2012 Tiddens HA. Editorial for effect of dornase alpha on inflammation and lung function: potential role in the early treatment of cystic fibrosis. J Cyst Fibros 2012; 11:77.
In this editorial, Harm Tiddens comments on the paper by Konstan and Ratjen (above) discussing the importance of early treatment of CF lung disease using dornase alpha and emphasising the need to preserve healthy lungs. Harms Tiddens reminds us that normal spirometry does not exclude chronic lower airway inflammation, infection and structural damage. He points out that large controlled trials tell us only about the group and not whether the patient in front of us will respond to a particular treatment. Until there are more reliable prediction models that allow us to predict outcome from an intervention for an individual based on key characteristics we are stuck with “one size fits all”. He supports the view of Konstan and Ratjen that there is ” a greater role for dornase alpha therapy in early treatment of CF where it may help preserve lung function and potentially extend survival”.

2016 Yang C; Chilvers M; Montgomery M; Nolan SJ. Dornase alfa for cystic fibrosis. [Review][Update of Cochrane Database Syst Rev. 2010;(3):CD001127; PMID: 20238314]Cochrane Database of Systematic Reviews. 4:CD001127, 2016.[PubMed]

To determine whether the use of dornase alfa in cystic fibrosis is associated with improved mortality and morbidity compared to placebo or other medications that improve airway clearance, and to identify any adverse events associated with its use.

Review of the published data on dornase alpha, the first really effective mucolytic for people with CF, confirms it is an excellent drug with a good safety record and undoubtedly one of the major therapeutic advances of the early Nineties (Shak et al, 1990; Fuchs et al, 1994).

2018 Newsome SJDaniel RMCarr SBBilton DKeogh RH.Investigating the effects of long-term dornase alfa use on lung function using registry data. J Cyst Fibros. 2018 Aug 29. pii: S1569-1993(18)30747-1. doi: 10.1016/j.jcf.2018.08.004. [Epub ahead of print]30172681 Full text available. [Pubmed]

Simon Newsome

Dornase alfa (DNase) is one of the commonest cystic fibrosis treatments and is often used for many years. However, studies have not evaluated the effectiveness of its long-term use. The authors aimed to use UK CF Registry data to investigate the effects of one-, two-, three-, four- and five-years of DNase use on lung function to see if the benefits of short-term treatment use are sustained long term.   They analysed data from 4,198 people in the UK CF Registry from 2007 to 2015 using g-estimation. By controlling for time-dependent confounding they estimated the effects of long-term DNase use on percent predicted FEV1 (ppFEV1) and investigated whether the effect differed by ppFEV1

Considering the population as a whole, there was no significant effect of one-year’s use of DNase; change in ppFEV1 over one year was -0.1% in the treated compared to the untreated (p = 0.51) and this did not change with long-term use. However, treatment was estimated to be more beneficial in people with lower lung function (p < 0.001); those with ppFEV1 < 70% at treatment initiation, showed an increase in lung function over one year that was sustained out to five years. The estimated effect of DNase did not depend on age (p = 0.35).

They concluded DNase improved lung function in individuals with reduced lung function, bringing a step-change in lung function, but no change in the slope of decline. There was no evidence for a benefit in lung function in those initiating treatment with ppFEV1 > 70%.

Simon Newsome is a Research Degree Student in Medical Statistics at the London School of Hygiene and Tropical Medicine. He has published previously on cardiovascular topics and the UK CF Registry.

Connie YangMark Montgomery.  Dornase alfa for cystic fibrosis. Cochrane Database Syst Rev 2021 Mar 18;3:CD001127.doi: 10.1002/14651858.CD001127.pub5.   [Pubmed]

        Connie Yang

Background: This is an update of a previously published review.(Full summary via PubMed abstract link)
Authors’ conclusions: There is evidence to show that, compared with placebo, therapy with dornase alfa may improve lung function in people with cystic fibrosis in trials lasting from one month to two years. There was a decrease in pulmonary exacerbations in trials of six months or longer, probably due to treatment. Voice alteration and rash appear to be the only adverse events reported with increased frequency in randomised controlled trials. There is not enough evidence to firmly conclude if dornase alfa is superior to other hyperosmolar agents in improving lung function.

Dr Connie Yang is Investigator and Paediatric Respirologist and Assoociate Professor in the Department of Pediatrics, Division of Respiratory Medicine, BC Children’s Hospital, Vancouver, Canada.

– It would be of interest to ask CF patients their opinion. The number taking regular Dornase Alpha would not support this guarded assessment. The proportion of people with CF who are taking dornase alpha is still increasing each year.


1999 Robinson M, Daviskas E, Eberi S, Baker J, Chan HK, Anderson SD, Bye PT. The effect of inhaled mannitol on bronchial mucus clearance in cystic fibrosis patients: a pilot study. Eur Respir J  1999; 14:678-685.[PubMed]
It has been postulated that hypertonic saline (HS) might impair the antimicrobial effects of defensins within the airways. Alternative non-ionic osmotic agents such as mannitol may thus be preferable to HS in promoting bronchial mucus clearance (BMC) in patients with cystic fibrosis (CF). This study reports the effect of inhalation of another osmotic agent, dry powder Mannitol (300 mg), compared with its control (empty capsules plus matched voluntary cough) and a 6% solution of HS on BMC in 12 patients with cystic fibrosis (CF). Mucus clearance was measured using a radioaerosol/gamma camera technique. Post-intervention clearance was measured for 60 min, followed by cough clearance for 30 min. Neither mannitol nor HS improved BMC during the actual intervention period compared with their respective controls. However during the post-intervention measurement there was a significant improvement in BMC for both the mannitol (8.7+/-3.3% versus 2.8+/-0.7%) and HS (10.0+/-2.3% versus 3.5+/-0.8%). There was also a significant improvement in cough clearance with the Mannitol (9.7+/-2.4%) compared with its control (2.5+/-0.8%). Despite premedication with a bronchodilator, a small fall in forced expiratory volume in one second (FEV1) was seen immediately after administration of both the mannitol (7.3+/-2.5%) and HS (5.8+/-1.2%). Values of FEV1 returned to baseline by the end of the study.

Inhaled mannitol is a potential mucoactive agent in cystic fibrosis patients. Further studies are required to establish the optimal dose and the long-term effectiveness of mannitol.

This was one of the first studies on inhaled mannitol in CF from Sydney.

2008 Jaques A, Daviskas E, Turton JA, McKay K, Cooper P, Stirling RG, Robertson CF, Bye PT, Lesouëf PN, Shadbolt B, Anderson SD, Charlton B. Inhaled mannitol improves lung function in cystic fibrosis. Chest 2008; 133:1388-1396.[PubMed]
This study examined the efficacy and safety of therapy with inhaled mannitol over a 2-week period in a randomized, double-blind, placebo-controlled, crossover study.
Thirty-nine subjects with mild-to-moderate CF lung disease inhaled 420 mg of mannitol or placebo twice daily for 2 weeks. Following a 2-week washout period, subjects were entered in the reciprocal treatment arm. Lung function, respiratory symptoms, quality of life, and safety were assessed. Mannitol treatment increased FEV(1) from baseline by a mean of 7.0% (95% confidence interval [CI], 3.3 to 10.7) compared to placebo 0.3% (95% CI, – 3.4 to 4.0; p < 0.001). The absolute improvement with mannitol therapy was 121 mL (95% CI, 56.3 to 185.7), which was significantly more than that with placebo (0 mL; 95% CI, – 64.7 to 64.7). The forced expiratory flow in the middle half of the FVC increased by 15.5% (95% CI, – 6.5 to 24.6) compared to that with placebo (increase, 0.7%; 95% CI, – 8.3 to 9.7; p < 0.02). The safety profile of mannitol was adequate, and no serious adverse events related to treatment were observed.

Inhaled mannitol treatment over a period of 2 weeks significantly improved lung function in patients with CF. Mannitol therapy was safe and well tolerated. Mannitol was developed further and eventually licensed in 2010.

2010 Minasian C, Wallis C, Metcalfe C, Bush A. Comparison of inhaled mannitol, daily rhDNase and a combination of both in children with cystic fibrosis: a randomised trial. Thorax 2010; 65:51-56. [PubMed]
Osmotic agents, such as inhaled dry powder mannitol, may increase mucociliary clearance by rehydrating the airway surface liquid and thus act as disease-modifying treatments in cystic fibrosis (CF). This is the first therapeutic trial of inhaled mannitol in children with CF; it was compared with recombinant human deoxyribonuclease (rhDNase), the current best established mucolytic treatment. METHODS: 38 children were recruited to an open crossover study. Subjects underwent an initial bronchial provocation challenge with dry powder mannitol. Those children with a negative challenge were randomly allocated to one of three consecutive 12-week treatment blocks (inhaled mannitol alone, nebulised rhDNase alone and mannitol + rhDNase). The primary outcome was forced expiratory volume in 1 s (FEV(1)). A number of secondary outcome measures were also studied. RESULTS: Only twenty children completed the study. Bronchoconstriction and cough associated with mannitol administration contributed to the high attrition rate. The mean increase in FEV(1) following 12 weeks of treatment was 0. 11 litres (6. 7%) (p = 0. 055) for mannitol alone, 0. 12 litres (7. 2%) (p = 0. 03) for rhDNase alone and 0. 03 litres (1. 88%) (p = 0. 67) for rhDNase and mannitol. None of the secondary clinical outcomes was statistically significantly different between treatments.

The authors concluded that inhaled mannitol was at least as effective as rhDNase after 3 months treatment. There was a marked individual variation in tolerance to mannitol and in response to treatment however. Children who do not respond to rhDNase many benefit from a trial of inhaled mannitol. The combination of mannitol and rhDNase was not useful.

This is a very useful study for those looking after patients with CF.

2010 Daviskas E, Anderson SD, Jaques A, Charlton B. Inhaled mannitol improves the hydration and surface properties of sputum in patients with cystic fibrosis. Chest 2010; 137:861-868[PubMed]
The airway mucus in patients with cystic fibrosis (CF) is dehydrated and adhesive and accumulates in the airways, resulting in chronic inflammation, infection, and progressive loss of lung function. Inhaled mannitol improves mucus clearance and, when administered over 2 weeks, it improves lung function in CF (Jaques et al. Chest 2008;133:1388-1396. [PubMed] above ). The changes in the physical properties of sputum after a 2-week treatment with mannitol were investigated in the same subjects with CF.

Sputum was collected before and at the end of the 2-week treatment period from 28 subjects with CF who participated in the double-blind crossover study. Mannitol or placebo 420 mg bid was inhaled over 2 weeks. The solids content, surface tension, contact angle, and viscoelasticity were measured.

Two-week treatment with mannitol reduced the solids from 7.3% +/- 3.0% to 5.7% +/- 3.0% (P = .012), surface tension from 83.1 +/- 7.2 to 78.6 +/- 8.0 mN/m (P < .039), and contact angle from 52.4 +/- 7.7 to 47.9 +/- 7.3 degrees. There was no significant change in the viscoelastic properties of sputum (P > .1). Placebo treatment had no significant effect on the sputum properties. The change in solids content correlated with the change in both FEV(1) (r = -0.78, P = .004) and forced expiratory flow in the middle half of the FVC (r = -0.80, P = .003), and the percentage change in surface tension and contact angle correlated with the percentage change in the FEV(1) (r = -0.73, P = .012 and r = -0.63, P = .03, respectively) in these subjects.

The authors concluded that treatment with inhaled mannitol over 2 weeks improved the hydration and surface properties of sputum in patients with CF. This effect was sustained and correlated with airway function changes.

2011 Chan JG, Kwok PC, Young PM, Chan HK, Traini D. Mannitol delivery by vibrating mesh nebulisation for enhancing mucociliary clearance, J Pharma Sci 2011; 100:2693-702. [PubMed]
Mucociliary clearance is compromised by airway surface liquid dehydration in respiratory disease states such as cystic fibrosis. Rehydration by hyperosmolar agents such as nebulised hypertonic saline and dry powder mannitol has demonstrated in vivo safety and efficacy for restoring mucociliary function. Mannitol, delivered as a nebulised formulation for this purpose, has not been investigated as yet. The current study examines the feasibility of delivering such a formulation using recent vibrating mesh technology. Nebulisation was conducted using an Aeroneb Go(TM) vibrating mesh nebuliser, and aerosol size was assessed by laser diffraction. Cascade impaction coupled with mass assay by high-performance liquid chromatography was used to confirm fluid uniformity and correlation with laser diffraction sizing. The following nebuliser formulations were prepared and aerosolised: deionised water, mannitol (150 mg/mL) aqueous solution, sodium chloride aqueous solution [0.2%, 1%, 3%, 5%, 7% (w/v)] and mannitol (150 mg/mL) in sodium chloride solution [0.2%, 1%, 3%, 7% (w/v)].

Mannitol aqueous solution was poorly nebulised, resulting in lengthy treatment times and large median droplet size. Addition of sodium chloride drastically improved nebuliser performance and aerosol characteristics. In vivo studies are necessary to confirm efficacy of nebulised mannitol. If substantiated, it could provide a pleasant-tasting alternative mucoactive agent with prolonged therapeutic action.

2011 Bilton D, Robinson P, Cooper P, Gallagher CG, Kolbe J, Fox H, Jaques A, Charlton B. CF301 Study Investigators.  Inhaled dry powder mannitol in cystic fibrosis: an efficacy and safety study. Eur Respir J 2011; 38:1071-80. [PubMed]
This international phase III study of inhaled dry powder mannitol was a randomised, double-blind, 26-week study, followed by a further 26-week, open-label (OL) extension. 324 cystic fibrosis (CF) patients were randomised, in a 3:2 ratio, to mannitol (400 mg b.i.d.) and control groups. The primary efficacy end-point was to determine the change in forced expiratory volume in 1 s (FEV1) over the double-blind phase. Secondary end-points included changes in forced vital capacity and pulmonary exacerbations.

A significant improvement in FEV1 was seen over 26 weeks (p<0.001) and was apparent by 6 weeks, irrespective of concomitant recombinant human deoxyribonuclease (rhDNase) use. At 26 weeks, there was a significant improvement in FEV1 of 92.9 mL for subjects receiving mannitol compared with controls (change from baseline 118.9 mL (6.5%) versus 26.0 mL (2.4%); p<0.001). Improvements in FEV1 were maintained up to 52 weeks in the OL part of the study. There was a 35.4% reduction in the incidence of having an exacerbation on mannitol (p=0.045). The incidence of adverse events (AEs) was similar in both groups, although treatment-related AEs were higher in the mannitol compared with the control group. The most common mannitol-related AEs were cough, haemoptysis and pharyngolaryngeal pain.

Mannitol showed sustained, clinically meaningful benefit in airway function in CF, irrespective of concomitant rhDNase use. Mannitol appears to have an acceptable safety profile for patients with CF.

2011 Teper A, Jaques A, Charlton B. Inhaled mannitol in patients with cystic fibrosis: A randomised open-label dose response trial. J Cyst Fibros 2011; 10:1-8.[PubMed]
This study was designed to determine the dose relationship of mannitol treatment and improvement in FEV(1) and FVC as well as safety. This was a randomised, open-label, crossover, dose response study. Following a 2-week treatment with mannitol 400mg b.i.d., 48 CF patients with a mean (SD) FEV(1) % predicted of 64 (13.2), received a further 3 treatments with 40mg, 120mg or 240mg b.i.d. for 2weeks each, in random order.

The study demonstrated a dose dependent increase in FEV(1) and FVC. The 400mg dose showed the greatest improvement and the 40mg dose had no discernible effect. The mean percent change in FEV(1) was -1.57%, 3.61%, 3.87% and 8.75% respectively for the 40mg, 120mg, 240mg and 400mg treatments. There was a statistically significant change in FEV(1) for 400mg compared to 40mg (p<0.0001) but the difference with 120mg and 240mg did not reach significance. The mean % change in FVC was -0.90, 1.74, 3.07 and 8.14, for the 40mg, 120mg, 240mg and 400mg treatment arms, with p=0.0001, p=0.0037 and p=0.0304 respectively when compared to 400mg. The highest tested dose of 400mg had a similar safety profile to the other doses tested. The change in FEV(1) and FVC by dose in the paediatric age group (<18years) was similar to the results in the adult population.

Based on these results the 400mg b.i.d. dose has been further studied in phase III trials.

2012 Aitken ML, Bellon GT, De Boeck K, Flume PA, Fox HG, Geller DE, Haarman EG, Hebestreit HU, Lapey A, Schou IM, Zuckerman JB, Charlton B. CF302 Investigators. Long-term inhaled dry powder mannitol in cystic fibrosis: an international randomized study.  Am J Respir Crit Care 2012; 185:645-652. [PubMed]
A study to determine whether long-term treatment with inhaled mannitol improves lung function and morbidity. This was a double-blind, randomized, controlled trial of inhaled mannitol, 400 mg twice a day (n = 192, “treated” group) or 50 mg twice a day (n = 126, “control” group) for 26 weeks, followed by 26 weeks of open-label treatment. The primary endpoint was absolute change in FEV(1) from baseline in treated versus control groups, averaged over the study period.

The treated group had a mean improvement in FEV(1) of 105 ml (8.2% above baseline). The treated group had a relative improvement in FEV(1) of 3.75% (P = 0.029) versus the control group. Adverse events and sputum microbiology were similar in both treatment groups. Exacerbation rates were low, but there were fewer in the treated group (hazard ratio, 0.74; 95% confidence interval, 0.42-1.32; P = 0.31), although this was not statistically significant. In the 26-week open-label extension study, FEV(1) was maintained in the original treated group, and improved in the original control group to the same degree.

The authors concluded inhaled mannitol, 400 mg twice a day, resulted in improved lung function over 26 weeks, which was sustained after an additional 26 weeks of treatment. The safety profile was also acceptable, demonstrating the potential role for this chronic therapy for CF.

Although the beneficial effects in the treated group were relatively modest effects this is one of the important new mucolytic treatments now available developed over the past decade. See also Bilton D et al. Eur Respir J 2011; 38:1071-1080. [PubMed] and early work by Robinson M et al. Eur Respir J 1999; 14:678-685.[PubMed] both above.

2012 Hurt K. Bilton D. Inhaled mannitol for the treatment of cystic fibrosis. Exp Rev Resp Med 2012; 6:19-26. [PubMed]
Inhaled dry powder mannitol is well established for use in bronchial provocation testing. Inhaled mannitol also increases mucociliary clearance, and therefore could have a role in treating chronic suppurative lung disease. There have been a number of studies in cystic fibrosis and bronchiectasis. An international Phase III trial has just been published that suggests the use of regular inhaled mannitol increases lung function and reduces exacerbation frequency in cystic fibrosis. Inhaled mannitol exerts its effects in a number of ways, most importantly like hypertonic saline, setting up an osmotic gradient so water flows into the airway lumen, increasing mucus hydration and mucociliary clearance. Its formulation as a dry powder makes it quick and convenient to take.

2013 Bilton D. Bellon G. Charlton B. Cooper P. De Boeck K. Flume PA. Fox HG. Gallagher CG. Geller DE. Haarman EG. Hebestreit HU. Kolbe J. Lapey A. Robinson P. Wu J. Zuckerman JB. Aitken ML. CF301 and CF302 Investigators. Pooled analysis of two large randomised phase III inhaled mannitol studies in cystic fibrosis. J Cyst Fibros 2013; 12:367-7. [PubMed]
To evaluate safety and efficacy of inhaled mannitol treatment in subgroups of a large global CF population. Data were pooled from two multicentre, double-blind, randomised, controlled, parallel group phase III studies in which 600 patients inhaled either mannitol (400 mg) or control (mannitol 50 mg) twice a day for 26 weeks. Both the mean absolute change in FEV(1) (mL) and relative change in FEV(1) by % predicted from baseline for mannitol (400 mg) versus control were statistically significant (73.42 mL, 3.56%, both p<0.001). Increases in FEV(1) were observed irrespective of rhDNase use. Significant improvements in FEV1 occurred in adults but not children (6-11) or adolescents (aged 12-17). Pulmonary exacerbation incidence was reduced by 29% (p=0.039) in the mannitol (400 mg) group.

The authors concluded there were sustained six-month improvements in lung function and decreased pulmonary exacerbation incidence indicate that inhaled mannitol is an important additional drug in the treatment of CF.

2014 Anonymous. Inhaled mannitol and cystic fibrosis. Unnecessary bronchial irritation. [Review] Prescribe International 2014; 23(148):89-91. [PubMed]
Mannitol in the form of capsules of powder for inhalation, is authorised in the European Union for use as a mucolytic in adults with cystic fibrosis. Two double-blind randomised trials have compared two doses of inhaled mannitol (400 mg or 50 mg, twice a day) in a total of 642 patients (57% adults) with cystic fibrosis. After 26 weeks of treatment, there was no difference between the groups in terms of clinical criteria such as the frequency of pulmonary exacerbations, quality of life, hospitalisation, or rescue antibiotic use. Inhaled mannitol increases the risk of bronchospasm and can also cause coughing and haemoptysis. A pretreatment test, used to exclude patients with bronchial hyperresponsiveness to mannitol, can also have noteworthy adverse effects.
The authors of this review consider this treatment is inconvenient, requiring inhalation of the contents of 10 mannitol capsules morning and evening; the capsules have to be placed one by one in the inhalation device, and the device must be replaced every week. In practice, patients with cystic fibrosis would be well advised to avoid inhaled mannitol.

This is a interesting article in an independent French journal expressing one view on the use of inhaled mannitol – a drug authorised in the European Union but not used in the USA. (See Topics -> Mucolytics – Mannitol for some of the previous work)

2017 De Boeck K, Haarman E, Hull J, Lands LC, Moeller A, Munck A, Riethmüller J, Tiddens H, Volpi S, Leadbetter J, Charlton B, Malfroot A; DPM-CF-204 Study Group. Inhaled dry powder mannitol in children with cystic fibrosis: A randomised efficacy and safety trial. J Cyst Fibros. 2017 May;16(3):380-387. doi: 10.1016/j.jcf.2017.02.003. Epub 2017 Mar 1.  [Pubmed]

     Kris De Boeck

This phase 2, randomised, placebo-controlled crossover study examined the efficacy of inhaled mannitol in children aged 6 – 17 yrs with cystic fibrosis (CF). Subjects were randomly assigned to mannitol 400 mg every 12 h or matching placebo for 8 weeks, followed by an 8 week washout and an 8 week period with the alternate treatment. The primary endpoint was the absolute change from baseline in ppFEV1 (percent predicted FEV1). A total of 92 subjects were studied. During mannitol treatment ppFEV1 was 3.42% (p=0.004) higher compared to placebo or a 4.97% (p=0.005) relative difference; relative change from baseline FEF25-75 was 10.52% (p=0.013). During mannitol treatment, acute post-treatment sputum weight was higher (p=0.012). In pre-specified subgroups (rhDNase use, age, and disease severity), the treatment differences consistently favoured mannitol. The most common AEs were cough and pulmonary exacerbations. Pulmonary exacerbation AEs were approximately 30% lower in the mannitol group.

In children with CF, inhaled mannitol was associated with significant improvements in lung function and sputum weight, irrespective of rhDNase use, age or disease severity. Inhaled mannitol was well tolerated and was associated with a reduced incidence of pulmonary exacerbation AEs.

–   In 2015 in the UK only 3.4% of all patients were taking inhaled mannitol and very few of these were children. By comparison 57.3% of all patients were taking rhDNase – more of these were children than adults. 27.4% of all patients were taking hypertonic saline relatively evenly distributed across the age range. The most tested and effective of these three mucolytic agents is rhDNase used by even more eligible patients in the USA (86%) than in UK (57.3%).

Patrick A FlumeElena AmelinaCori L DainesBrett Charlton, Joanna LeadbetterAlessandro Guasconi Moira L Aitken. Efficacy and safety of inhaled dry-powder mannitol in adults with cystic fibrosis: An international, randomized controlled study.  J Cyst Fibros 2021 Mar 11;S1569-1993(21)00046-1.doi: 10.1016/j.jcf.2021.02.011.Online ahead of print. [Pubmed]Free article

Patrick Flume

Background: Mannitol is a mucoactive hyperosmotic agent used as add-on therapy in patients with cystic fibrosis (CF), administered twice-daily (BID) via a small, portable, breath-actuated dry-powder inhaler. This study was conducted to provide confirmatory evidence of mannitol’s efficacy and safety in adults.
Methods: This multicenter, double-blind, randomized, parallel-group, controlled clinical trial recruited adults (aged ≥18 years) with CF, and forced expiratory volume in 1 second (FEV1) 40-90% predicted. Subjects received either mannitol 400 mg or mannitol 50 mg (control), BID via dry-powder inhaler for 26 weeks. Primary endpoint: FEV1 averaged over the 26-week treatment period.
Results: Of 423 subjects randomized (209 or 214 receiving mannitol 400 mg BID or control, respectively), 373 (88.2%) completed the study, with a similar proportion completing in the two groups. For FEV1 averaged over 26 weeks, mannitol 400 mg BID was statistically superior to control (adjusted mean difference 54 mL [95% CI 8, 100 mL]; p = 0.020). This was supported by sensitivity analyses of the primary endpoint, and by observed improvements in secondary pulmonary function endpoints (eg, absolute adjusted mean difference in percent predicted FEV1averaged over 26 weeks 1.21% [0.07%, 2.36%]; p = 0.037). Adverse events were mainly mild or moderate in severity, with treatment-related adverse events in 15.5 and 12.2% of subjects receiving mannitol 400 mg BID and control, respectively.

Conclusions: In adults with CF, mannitol 400 mg BID inhaled as a dry-powder statistically significantly improved lung function (FEV1) compared with control, with this improvement supported by sensitivity analyses and secondary pulmonary function endpoints. Mannitol had a good overall safety and tolerability profile. NCT02134353.

Dr Patrick Flume is at the Medical University of South Carolina, Charleston, SC, United States.

– In UK, where inhaled mannitol has been available for some years, the use is very modest. Only 5.9% of patients were taking regular mannitol – most were adult patients over 16 years of age.


Most of these references are to respiratory use – earlier publications desribe use in meconium ileus, meconium ileus equivalent (DIOS) and abdominal pain and are dealt with separately at the end of this section.

1962 Webb WR. Clinical evaluation of a new mucolytic agent acetyl-cysteine. J Thorac Cardiovasc Surg 1962; 44:330-343. [PubMed]

24 hour sputum collections from an adult with chronic bronchitis after starting N Acetylcysteine on day 2

Acetyl cysteine, a derivative of the amino acid cysteine, is a drug that subsequently was widely used for CF in Europe but never popular in the UK. Here experience is reported of 285 patients with a variety of suppurative pulmonary conditions and “revealed it to be extremely effective with almost no associated complications. Seven patients with CF improved over 10 months with either inhalations or sleeping in a tent with the drug nebulised with saline and propylene glycol”. (figure).
Apparently N-acetylcysteine and other sulphydryl compounds act by depolymerising mucus in vitro by breaking disulphide bonds of the glycoproteins thereby lowering the viscosity (Sheffner AL et al. Ann N Y Acad Sci 1963; 106:298-310).

This paper contains a useful summary of all the many side effects of animal-derived trypsin and enzymatic treatments used to liquefy sputum – contrasted with the minimal side effects experienced with N-acetylcysteine.

Interestingly there has been a renewal of interest in acetyl cysteine in the Millennium and the drug has been used both for respiratory (6.5% of USA patients with CF take inhaled acetyl cysteine) and gastrointestinal problems in CF (Lillibridge CB et al. Oral administration of n-acetyl cysteine in the prophylaxis of “meconium ileus equivalent” J Pediatr 1967; 71:887-9; Gracey M et al. Treatment of abdominal pain in cystic fibrosis by oral administration of n-acetyl cysteine. Arch Dis Child 1969; 44:404-405).

More recently the relation to glutathione, in particular, has featured in recent references as N-acetylcysteine is an effective precursor of cysteine for tissue glutathione synthesis. Apparently CFTR is responsible for glutathione transport and there may be intracellular accumulation of glutathione in cystic fibrosis (Childers M et al. Medical Hypotheses 2007; 68:101-102. [PubMed]).

1963 Reas HW. The effect of N-acetylcysteine on the viscosity of tracheobronchial secretions in cystic fibrosis of the pancreas. J Pediatr 1963; 62:31-5. [PubMed] (Also Reas HW. South Med J. 1963; 56:1271-1278. [PubMed]).
Viscosity measurements were determined on secretions obtained via tracheotomies from 2 patients with CF with the use of N-acetylcysteine aerosol which produced a greater fall in the viscosity of the secretions than did a control aerosol (also Webb 1962 above). The authors suggest that “The combination of this safe method of mucolysis with energetic postural drainage and physiotherapy may be very rewarding in the easier removal of retained pulmonary secretions”. (Also Suddarth SB. Acetylcysteine a new and effective mucolytic agent. Bulletin – Grainger Medical Center 1963; 15:65-69 above; Meeker IA Jr, Kincannon WN. Acetyl cysteine used to liquefy inspissated meconium causing intestinal obstruction in the newborn. Surgery, St Louis 1964; 56:419-425).

Obviously in the early Sixties there was considerable interest in this new mucolytic agent whose free sulphydryl group reduced the disulphide linkages of mucoproteins. Subsequently it was the subject of a number of publications in liquefying sputum, improving abdominal pain and treating meconium ileus but never became popular in the UK as part of the pulmonary treatment. Although a subsequent review found no evidence of benefit (Duijvestijn YC & Brand PL. Acta Paediatr 1999; 88:38-41.[PubMed]), Ratjen et al (Eur J Pediatr 1985; 144:374-378.[PubMed]) found in a 12 week oral trial of NAC, ambroxal and placebo that “although no clinical differences could be observed between the three groups, significant impairment in the placebo group was found for trapped air and FEV1 when compared to the active groups, suggesting a therapeutic effect of ambroxal and NAC in CF”. More recently the relation to glutathione has caused renewed interest in the drug which, when given orally in high doses, provides a source of glutathione and apparently reduces airway inflammation (Tirouvanziam R, et al. Proc Nat Acad Sc 2006; 103:4628-4633. below).

2006 Tirouvanziam R, Conrad CK, Bottiglieri T, Herzenberg LA, Moss RB, Herzenberg LA.High-dose oral N-acetylcysteine, a glutathione prodrug, modulates inflammation in cystic fibrosis. Proc Nat Acad Sci USA 2006; 103:4628-33[PubMed] Neutrophilic airway inflammation is a hallmark of cystic fibrosis (CF). As high oxidant producers, airway neutrophils contribute largely to the systemic redox imbalance seen in CF. In turn, this chronic and profound imbalance can impact circulating neutrophils before their migration into airways.

Indeed, in 18 CF patients with stable disease, blood neutrophils were readily deficient in the pivotal antioxidant glutathione (P = 0.003, compared with 9 healthy controls). In a phase 1 study, this deficiency was improved (P = 0.025) by the glutathione prodrug N-acetylcysteine, given orally in high doses (0.6 to 1.0 g three times daily, for 4 weeks). This treatment was safe and markedly decreased sputum elastase activity (P = 0.006), the strongest predictor of CF pulmonary function. Consistently, neutrophil burden in CF airways was decreased upon treatment (P = 0.003), as was the number of airway neutrophils actively releasing elastase-rich granules (P = 0.005), as measured by flow cytometry. Pulmonary function measures were not improved, as expected with short-term treatment.

After excluding data from subjects without baseline airway inflammation, positive treatment effects were more pronounced and included decreased sputum IL-8 levels (P = 0.032). Thus, high-dose oral N-acetylcysteine has the potential to counter the intertwined redox and inflammatory imbalances in CF.

Conflicting views on the effect of N-acetylcysteine appear despite the Cochrane Review conclusion that it is of no benefit in CF.

2009 Dauletbaev N, Fischer P, Aulbach B, Gross J, Kusche W. Thyroff-Friesinger U, Wagner TO, Bargon J. A phase II study on safety and efficacy of high-dose N-acetylcysteine in patients with cystic fibrosis. Euro J Med Res 2009; 14:352-358. [PubMed]
A single-centre, randomised, double-blinded, placebo-controlled phase II clinical study to test safety and efficacy of a 12-week therapy with low-dose (700 mg/daily) or high-dose (2800 mg/daily) of NAC. High-dose NAC was a well-tolerated and safe medication but did not alter clinical or inflammatory parameters. However, extracellular glutathione in induced sputum tended to increase on high-dose NAC. The authors concluded that high-dose NAC is a well-tolerated and safe medication for a prolonged therapy of patients with CF with a potential to increase extracellular glutathione in CF airways.

This study confirms the lack of clinical effect of N-acetylcysteine on the respiratory function and inflammatory parameters in CF but the increase in extracellular glutathione may be of some benefit. It is difficult to reconcile the lack of clinical effect with some of the early reports showing marked increase in the volume of sputum; also the clinical experience suggesting some benefit. The effects are complicated – even recently it has been reported that that NAC causes a significant efflux of Cl from CF bronchial epithelial cells (Varelogianni G et al. 2010 [PubMed] below).

2010 Varelogianni G, Oliynyk I, Johannesson M. The effect of N-acetylcysteine on chloride efflux from airway epithelial cells. Cell Biology International 2010; 34:245-252. [PubMed]
N-acetylcysteine (NAC) is a well known mucolytic and antioxidant drug, and an indirect precursor of glutathione. Since GSNO (S-nitrosoglutathione) previously has been shown to be able to promote Cl- efflux from CF airway epithelial cells, it was investigated whether NAC also could stimulate Cl- efflux from CF and non-CF epithelial cells and through which mechanisms. CF bronchial epithelial cells (CFBE) and normal bronchial epithelial cells (16HBE) were treated with 1 mM, 5 mM, 10 mM or 15 mM NAC for 4 h at 37 degrees C. The effect of NAC on Cl- transport was measured by Cl- efflux measurements and by X-ray microanalysis. Cl- efflux from CFBE cells was stimulated by NAC in a dose-dependent manner, with 10 mM NAC causing a significant increase in Cl- efflux with nearly 80% in CFBE cells. The intracellular Cl- concentration in CFBE cells was significantly decreased up to 60% after 4 h treatment with 10 mM NAC. Moreover immunocytochemistry and Western blot experiments revealed expression of CFTR channel on CFBE cells after treatment with 10 mM NAC. The stimulation of Cl- efflux by NAC in CF airway epithelial cells may improve hydration of the mucus and thereby be beneficial for CF patients.

This is yet another interesting paper on NAC which although used as a mucolytic in Europe since the first reports (1962 Webb WR. Clinical evaluation of a new mucolytic agent acetyl-cysteine. J Thorac Cardiovasc Surg 1962; 44:330-343. [PubMed] above) has not found favour in the UK nor has performed well in CF patients in recent trials. The more recent relationship as a precursor to glutathione adds further interest to the NAC story. Apparently N-acetylcysteine and other sulphydryl compounds act by depolymerising mucus in vitro by breaking disulphide bonds of the glycoproteins thereby lowering the viscosity (Sheffner AL. Ann N Y Acad Sci 1963; 106:298-310. [PubMed]).

2011 Suk JS, Lai SK, Boylan NJ, Dawson MR, Boyle MP, Hanes J. Rapid transport of muco-inert nanoparticles in cystic fibrosis sputum treated with N-acetyl cysteine. Nanomedicine UK. 2011; 6:365-675. [PubMed]
Sputum poses a critical diffusional barrier that strongly limits the efficacy of drug and gene carriers in the airways of individuals with cystic fibrosis. Previous attempts to enhance particle penetration of CF sputum have focused on either reducing its barrier properties via mucolytics, or decreasing particle adhesion to sputum constituents by coating the particle surface with non-mucoadhesive polymers, including polyethylene glycol (PEG). Neither approach has enabled particles to penetrate expectorated sputum at rates previously observed for non-mucoadhesive nanoparticles in human cervicovaginal mucus.

The authors sought to investigate whether a common mucolytic, N-acetyl cysteine (NAC), in combination with dense PEG coatings on particles, can synergistically enhance particle penetration across fresh undiluted CF sputum. They used high-resolution multiple particle tracking to measure the diffusion of uncoated and PEG-coated nanoparticles in native and NAC-treated CF sputum. They discovered that 200 nm particles, if densely coated with PEG, were able to penetrate CF sputum pretreated with NAC with average speeds approaching their theoretical speeds in water. Based on the rapid penetration of PEG-coated particles in NAC-treated sputum, they determined that the average spacing between sputum mesh elements was increased from 145 +/- 50 nm to 230 +/- 50 nm upon NAC treatment. Mathematical models based on particle transport rates suggest as much as 75 and 30% of 200 and 500 nm PEG-coated particles, respectively, may penetrate a physiologically thick NAC-treated CF sputum layer within 20 min. Uncoated particles were trapped in CF sputum pretreated with NAC nearly to the same extent as in native sputum, suggesting that NAC treatment alone offered little improvement to particle penetration.

The authors concluded that NAC facilitated rapid diffusion of PEG-coated, muco-inert nanoparticles in CF sputum and that their results provided a promising strategy to improve drug and gene carrier penetration in CF sputum, offering hope for improved therapies for CF.

The N-acetylcysteine story in relation to CF is quite remarkable. Although declared to be well tolerated with no significant adverse effects but without evidence of significant clinical benefit in CF, reports of its use keep appearing!

The CF Foundation Drug Pipeline states in 2012 – “A placebo controlled 12-week Phase 2 trial at Stanford University demonstrated a decrease in inflammatory cells in the lung and improvement in pulmonary function. Results from a Phase 2b multicentre trial did not reproduce these findings but an improvement in lung function was noted”.

A Cochrane Database Systematic Review in 2009 ([PubMed])on nebulized and oral thiol derivatives for pulmonary disease in cystic fibrosis “found no evidence to recommend the use of either nebulized or oral thiol derivatives in people with cystic fibrosis. There are very few good quality trials investigating the effect of these medications in cystic fibrosis, and further research is required to investigate the potential role of these medications in improving the outcomes of people with cystic fibrosis”.

2014 Kettle AJ. Turner R. Gangell CL. Harwood DT. Khalilova IS. Chapman AL. Winterbourn CC. Sly PD. AREST CYSTIC FIBROSIS. Oxidation contributes to low glutathione in the airways of children with cystic fibrosis. Respir J 2014; 44(1):122-9.[PubMed]
Glutathione is an important antioxidant in the lungs but its concentration is low in the airways of patients with cystic fibrosis. The concentration of glutathione was lower in bronchoalveolar lavage from children with cystic fibrosis, whereas glutathione sulfonamide, a specific oxidation product of hypochlorous acid, was higher. Oxidised glutathione and glutathione sulfonamide correlated with myeloperoxidase and a biomarker of hypochlorous acid. The percentage of glutathione attached to proteins was higher in children with cystic fibrosis than controls. Pulmonary infections in cystic fibrosis resulted in lower levels of glutathione but higher levels of oxidised glutathione and glutathione sulfonamide in bronchoalveolar lavage.
The concentration of glutathione is low in the airways of patients with cystic fibrosis from an early age. Increased oxidation of glutathione by hypochlorous acid and its attachment to proteins contribute to this deficiency. Therapies targeted against myeloperoxidase may boost antioxidant defence and slow the onset and progression of lung disease in cystic fibrosis.

Further work on glutathione – a compound that has received increasing attention in recent years.(please see Topic)

2014 Marson FA. Bertuzzo CS. Ribeiro AF. Ribeiro JD. Polymorphisms in the glutathione pathway modulate cystic fibrosis severity: a cross-sectional study. BMC Medical Genetics 2014; 15:27.[PubMed]
A cross-sectional study of 180 CF patients was carried out from 2011 to 2012. The authors analysed CFTR mutations, polymorphisms (GSTM1 and GSTT1 deletions, GSTP1 + 313A > G, GCLC-129C > T, and GCLC-3506A > G) in modifier genes and CF clinical severity as assessed by 28 clinical and laboratory variables. Significant associations were found between modifier gene polymorphisms and particular phenotypes or genotype changes. These included GCLC-129C > T with a higher frequency of the Pseudomonas aeruginosa mucoid to CC genotype (p = 0.044), and GCLC-3506A > G with a higher frequency of the no-mucoid P. aeruginosa (NMPA) to AA genotype (p = 0.012). The GSTT1 deletion was associated with a higher frequency of the NMPA to homozygous deletion (p = 0.008), GSTP1 + 313A > G with a minor risk of osteoporosis (p = 0.036), and patient age < 154 months (p = 0.044) with the AA genotype. The Bhalla score was associated with GCLC-3506A > G (p = 0.044) and GSTM1/GSTT1 deletion polymorphisms (p = 0.02), while transcutaneous hemoglobin oxygen saturation levels were associated with GSTT1 deletions (p = 0.048). The authors conclude that CF severity is associated with polymorphisms in GSH pathways and CFTR mutations.

Apparently these results show that, although a monogenic disease, CF is heavily influenced in its clinical characteristics, evolution and severity by polymorphisms in modifier genes. Nevertheless, there is still a long way before the dynamics of polymorphisms in genes active in the GSH metabolic pathway and involved in detoxification in CF are fully understood.

2014 Rushworth GF. Megson IL Existing and potential therapeutic uses for N-acetylcysteine: the need for conversion to intracellular glutathione for antioxidant benefits. Pharmacol Ther 2014; 141(2):150-8. [PubMed]
N-acetyl-l-cysteine (NAC) has long been used therapeutically for the treatment of acetaminophen (paracetamol) overdose, acting as a precursor for substrate(l-cysteine) in synthesis of hepatic glutathione (GSH) depleted through drug conjugation. Other therapeutic uses of NAC have also emerged, including the alleviation of clinical symptoms of cystic fibrosis through cysteine-mediated disruption of disulfide cross-bridges in the glycoprotein matrix in mucus. More recently, however, a wide range of clinical studies have reported on the use of NAC as an antioxidant, most notably in the protection against contrast-induced nephropathy and thrombosis. The results from these studies are conflicting and a consensus is yet to be reached regarding the merits or otherwise of NAC in the antioxidant setting.
This review seeks to re-evaluate the mechanism of action of NAC as a precursor for GSH synthesis in the context of its activity as an “antioxidant”. Results from recent studies are examined to establish whether the pre-requisites for effective NAC-induced antioxidant activity (i.e. GSH depletion and the presence of functional metabolic pathways for conversion of NAC to GSH) have received adequate consideration in the interpretation of the data. A key conclusion is a reinforcement of the concept that NAC should not be considered to be a powerful antioxidant in its own right: its strength is the targeted replenishment of GSH in deficient cells and it is likely to be ineffective in cells replete in GSH.

There is an extensive literature on the use of NAC in cystic fibrosis. Despite most impressive early papers showing obvious increasing in sputum following administration of the drug, the current view seems to be that there is no significant benefit from its use – which is surprising (suggest see Topics -> Mucolytics -> N-acetylcysteine).

2015 Skov M; Pressler T; Lykkesfeldt J; Poulsen HE; Jensen PO; Johansen HK; Qvist T; Kraemer D; Hoiby N; Ciofu O. The effect of short-term, high-dose oral N-acetylcysteine treatment on oxidative stress markers in cystic fibrosis patients with chronic P. aeruginosa infection — a pilot study.  J Cyst Fibros 2015; 14(2):211-8.  [PubMed]
Supplementation with anti-oxidants is potentially beneficial for CF patients. The effect of 4 weeks of oral N-acetylcysteine (NAC) treatment (2400 mg/day divided into two doses) on biochemical parameters of oxidative stress was investigated in an open-label, controlled, randomised trial on 21 patients; 11 patients in the NAC group and 10 in the control group. Biochemical parameters of oxidative burden and plasma levels of antioxidants were assessed at the end of the study and compared to the baseline values in the two groups.
A significant increase in the plasma levels of the antioxidant ascorbic acid (p=0.037) and a significant decrease in the levels of the oxidized form of ascorbic acid (dehydroascorbate) (p=0.004) compared to baseline were achieved after NAC treatment. No significant differences were observed in the control group. The parameters of oxidative burden did not change significantly compared to baseline in either of the groups.
A better lung function was observed in the NAC treated group with a mean (SD) change compared to baseline of FEV1% predicted of 2.11 (4.6), while a decrease was observed in the control group (change -1.4 (4.6)), though not statistically significant.
The authors concluded treatment with N-acetylcysteine 1200 mg x 2/day for 30 days significantly decreased the level of oxidised vitamin C and increased the level of vitamin C (primary end-points) and a non statistically significant improvement of lung function was observed in this group of patients.

– Further modest evidence that N-acetylcysteine had a significant effect on the antioxidant status of people with CF.  (Some past papers from as far back as 1962 are reviewed in Topics -> Mucolytics -> N-acetylcysteine).

2015 Hussain S; Varelogianni G; Sarndahl E; Roomans GM.  N-acetylcysteine and azithromycin affect the innate immune response in cystic fibrosis bronchial epithelial cells in vitro. Lung Res 2015; 41(5):251-60. [PubMed]
The authors previously reported that N-acetylcysteine (NAC), ambroxol and azithromycin (AZM) (partially) correct the chloride efflux dysfunction in cystic fibrosis bronchial epithelial (CFBE) cells with the DF508 homozygous mutation in vitro. Here they further investigated possible immunomodulatory effects of these drugs on the regulation of the innate immune system by studying the expression of the cytosolic NOD-like receptors NLRC1 and NLRC2, and interleukin (IL)-6 production in CFBE cells. Overall, the results indicate that NAC and AZM not only can correct the chloride efflux dysfunction but also have a weakly strengthening effect on the innate immune system.

–  The effect of N-acetylcysteine in CF has been the subject of numerous studies since the first publication describing a “new mucolytic agent” by  Webb et al in 1962 (above).
Despite considerable published evidence of potential benefit in CF, the drug has never been popular for treating people with CF in the UK but is used in Europe. Indeed, a Cochrane review in 2013 “found no evidence to recommend the use of either inhaled or oral thiol derivatives in people with cystic fibrosis. There are very few good quality trials investigating the effect of these medications in cystic fibrosis, and further research is required to investigate the potential role of these medications in improving the outcomes of people with cystic fibrosis” (Tam J et al, Cochrane Database Syst Rev2013;7:CD007168).


1964 Meeker IA Jr. Acetyl cysteine used to liquefy inspissated meconium causing intestinal obstruction in the newborn. Surgery 1964; 56:419-425. [PubMed]
100ml 0f 20% acetyl cysteine and equal parts of 1% hydrogen peroxide were introduced into the lumen of the bowel where it remains for 30 minutes. Bowel resection was then not necessary.

1967 Lillibridge CB, Docter JM, Eidelman S. Oral administration of n-acetyl cysteine in the prophylaxis of “meconium ileus equivalent”. J Pediatr 1967; 71:887-889.[PubMed]
An adult with CF was chronically disabled by frequent abdominal pain and episodes of faecal impaction. Treatment with oral acetyl cysteine 30ml three time daily led to almost complete cessation of the attacks. The patients gained weight and became fully employed. This is the first report of this treatment in an older patient with CF.

1969 Gracey M, Burke V, Anderson CM. Treatment of abdominal pain in cystic fibrosis by oral administration of n-acetyl cysteine. Arch Dis Child 1969; 44:404-405.[PubMed]
Gracey later confirmed in 1975 that “this troublesome complaint may be relieved by giving n-acetyl cysteine by mouth and further personal experience confirms the value of this form of therapy. Sometimes up to 15ml of a 20% solution 3 or 4 times a day may be necessary at first”

1976  Hodson ME, Mearns MB, Batten JC. Meconium ileus equivalent in adults with cystic fibrosis of pancreas: a report of six cases. Br Med J 1976; 2(6039):790-791. [PubMed]
Eleven episodes of “meconium ileus equivalent” have been seen in six adults with cystic fibrosis of the pancreas. Three patients were initially treated surgically; one died and the other two developed serious postoperative chest infections. Six episodes were successfully treated medically with acetylcysteine orally and by enema, nasogastric suction, and intravenous fluids. Operation should be avoided if possible, and maintenance treatment with acetylcysteine may be necessary to prevent relapse.


Conclusions were that cough is common in infants with CF, but few present with crackles/wheeze or CXR changes. Pseudomonas is associated with use of PPI or PPI plus H2 blocker, but not with respiratory hospitalization. These observations cannot prove cause and effect but add to our understanding of pulmonary manifestations of CF in infants

Dr Danielle Goetz is paediatric Pulmonologist in the Dept. of Pediatrics, Jacobs School of Medicine, University of Buffalo

Gomez CCS, Parazzi PLF, Clinckspoor KJ, Mauch RM, Pessine FBT, Levy CE, Peixoto AO, Ribeiro MÂGO, Ribeiro AF, Conrad D, Quinton PM, Marson FAL, Ribeiro JD.  Safety, Tolerability, and Effects of Sodium Bicarbonate Inhalation in Cystic Fibrosis.  Clin Drug Investig. 2019 Nov 13. doi: 10.1007/s40261-019-00861-x. [Epub ahead of print]  [Pubmed]

Carla C S Gomez

Among the many consequences of loss of CFTR protein function, a significant reduction of the secretion of bicarbonate (HCO3-) in cystic fibrosis (CF) is a major pathogenic feature. Loss of HCO3- leads to abnormally low pH and impaired mucus clearance in airways and other exocrine organs, which suggests that NaHCO3 inhalation may be a low-cost, easily accessible therapy for CF.
To evaluate the safety, tolerability, and effects of inhaled aerosols of NaHCO3 solutions (4.2% and 8.4%) an experimental, prospective, open-label, pilot, clinical study was conducted with 12 CF volunteer participants over 18 years of age with bronchiectasis and pulmonary functions classified as mildly to severely depressed. Sputum rheology, pH, and microbiology were examined as well as spirometry, exercise performance, quality-of-life assessments, dyspnea, blood count, and venous blood gas levels.
The sputum pH increased immediately after inhalation of NaHCO3 at each clinical visit and was inversely correlated with rheology when all parameters were evaluated: [G’ (elasticity of the mucus) = - 0.241; G″ (viscosity of the mucus) = - 0.287; G* (viscoelasticity of the mucus) = - 0.275]. G* and G’ were slightly correlated with peak flow, forced expiratory volume in 1 s (FEV1), and quality of life; G″ was correlated with quality of life; sputum pH was correlated with oxygen consumption (VO2) and vitality score in quality of life. No changes were observed in blood count, venous blood gas, respiratory rate, heart rate, peripheral oxygen saturation of haemoglobin (SpO2), body temperature, or incidence of dyspnea. No adverse events associated with the study were observed.

The authors concluded nebulized NaHCO3 inhalation appears to be a safe and well tolerated potential therapeutic agent in the management of CF. Nebulized NaHCO3 inhalation temporarily elevates airway liquid pH and reduces sputum viscosity and viscoelasticity. They did however note that even though most measured parameters did not achieve statistical significance, the means of the measurements of effects almost always remained constant or changed in the direction of presumed improvement, giving confidence that the treatment did not depress or impede normal function. The favourable changes observed in several parameters in this study may support inhalation of nebulized NaHCO3 as a safe and well-tolerated therapeutic agent in the management of CF and possibly other obstructive lung diseases. 

The authors  are from Center for Investigation in Pediatrics, Department of Pediatrics, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, 126, Tessália Vieira de Camargo, Campinas, São Paulo, Brazil. except for Paul Quinton and Douglas Conrad who are from the University of California San Diego School of Medicine; they provided the project concept and edited the manuscript. Paul Quinton has for many years emphasised the role of bicarbonate.


Ehre CRushton ZLWang BHothem LNMorrison CBFontana NCMarkovetz MRDelion MFKato TVillalon DThelin WREsther CR JrHill DBGrubb BRLivraghi-Butrico ADonaldson SHBoucher RC.An Improved Inhaled Mucolytic to Treat Airway Muco-Obstructive Diseases.Am J Respir Crit Care Med. 2018 Sep 13. doi: 10.1164/rccm.201802-0245OC. [Epub ahead of print]    [Pubmed]

Camille Ehre

Dithiothreitol (DTT) and a novel mucolytic agent, P3001, were directly compared to N-acetylcysteine (NAC) in vitro and both exhibited superior reducing activities. In vivo, P3001 significantly decreased lung mucus burden in βENaC over-expressing mice whereas NAC did not. In NAC-treated CF patients, deposited NAC was rapidly cleared from the lungs and was ineffective on sputum biophysical properties. In contrast, P3001 acted faster and at lower concentrations than NAC, and was more effective than DNase, in CF sputum ex vivo.

The authors consider these results suggest that reducing the viscoelasticity of airway mucus is an achievable therapeutic goal with P-3001 class mucolytic agents.

Dr. Camille Ehre is Assistant Professor at the Marsico Lung Institute, University of North Carolina School of Medicine

van Heusden C, Button B, Anderson WH, Ceppe A, Morton LC, O’Neal WK, Dang H, Alexis NE, Donaldson SH, Stephan H, Boucher RC, Lazarowski ER.  Inhibition of ATP hydrolysis restores airway surface liquid production in cystic fibrosis airway epithelia.  Am J Physiol Lung Cell Mol Physiol. 2019 Dec 4. doi: 10.1152/ajplung.00449.2019.[Pubmed]
Airway surface dehydration is a pathological feature of cystic fibrosis (CF) lung disease. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR), a cyclic AMP-regulated Cl- channel controlled in part by the adenosine A2B receptor. An alternative, CFTR-independent mechanism of fluid secretion is regulated by ATP, via the P2Y2 receptor (P2Y2R) that activates Ca2+-regulated Cl- channels (CaCC/TMEM16) and inhibits Na+ absorption. However, due to rapid ATP hydrolysis, steady-state ATP levels in CF airway surface liquid (ASL) are inadequate to maintain P2Y2R-mediated fluid secretion. Therefore, inhibiting airway epithelial ecto-ATPases to increase ASL ATP levels constitutes a strategy to restore airway surface hydration in CF. Using [γ32P]ATP as radiotracer, we assessed the effect of a series of ATPase inhibitory compounds on the stability of physiologically occurring ATP concentrations. We identified the polyoxometalate [Co4(H2O)2(PW9O34)2]10- (POM-5) as the most potent and effective ecto-ATPase inhibitor in CF airway epithelial cells. POM-5 caused long-lasting inhibition of ATP hydrolysis in airway epithelia, which was reversible upon removal of the inhibitor. Importantly, POM-5 markedly enhanced steady-state levels of released ATP, promoting increased ASL volume in CF cell surfaces. These results provide proof-of-concept for ecto-ATPase inhibitors as therapeutic agents to restore hydration of CF airway surfaces. As a test of this notion, cell-free sputum supernatants from CF subjects were studied and found to have abnormally elevated ATPase activity, which was markedly inhibited by POM-5.

From the University of North Carolina at Chapel Hill