NEW YORK (Reuters Health) – Long-term inhalation therapy with dry-powder mannitol improves lung function in patients with cystic fibrosis (CF), a multinational team reports in the American Journal of Respiratory and Critical Care Medicine online December 28.

“The safety profile was also acceptable, demonstrating the potential role for this chronic therapy for CF,” the authors report.

They note in their introduction that mannitol is an osmotic agent that when inhaled hydrates airway surfaces and thus aids mucus clearance.  Since mannitol is a powder and can be dispensed from a simple dry powder inhaler, it may have advantages over other therapies that require refrigeration or nebulization.

Dr. Moira L Aitken, with the University of Washington Medical Center in Seattle, Washington, and colleagues at 53 sites in North and South America and Europe conducted a double-blind randomized 26-week trial in which 192 CF patients were assigned to inhaled mannitol 400 mg bid while 126 patients made up a control group in which they were given mannitol 50 mg bid – a dose chosen based the findings of a prior dose-ranging trial.

About half the patients were adults, and ages ranged from 6 to 53 years.  All participants had an FEV1 of 40-89% predicted.  All other treatments except nebulized saline were continued.

The absolute increase in FEV1 from baseline was 106.5 mL in the mannitol group compared with 52.4 mL in the control group.  The difference in the relative change in FEV1 between the two groups of 3.75% was significant (p=0.029), the investigators found.

The incidence of severe adverse events was almost identical in the two arms, at 15.8% in the mannitol group and 15.7% in the control group.  Respective rates of serious treatment-related adverse events were 2.2% and 2.3%, the data indicate.  Furthermore, there were no qualitative changes in microbiology in either arm over the study period.

The trial was followed by a 26-week extension in which all patients received active treatment.  During this period, the improvement seen in the original active treatment group was maintained while FEV1 improved to the same degree in the original control group, Dr. Aitken and colleagues report.

“The efficacy of inhaled mannitol was demonstrated on top of a background of typical concomitant therapy such as rhDNase and inhaled antibiotics,” they point out.  “These results support the use of mannitol as an osmotic, inhalation dry powder treatment for the daily management of CF patients to improve overall pulmonary function with a shortened time of treatment burden,” they conclude.

The incidence of severe adverse events was almost identical in the two arms, at 15.8% in the mannitol group and 15.7% in the control group.  Respective rates of serious treatment-related adverse events were 2.2% and 2.3%, the data indicate.  Furthermore, there were no qualitative changes in microbiology in either arm over the study period.

The trial was followed by a 26-week extension in which all patients received active treatment.  During this period, the improvement seen in the original active treatment group was maintained while FEV1 improved to the same degree in the original control group, Dr. Aitken and colleagues report.

“The efficacy of inhaled mannitol was demonstrated on top of a background of typical concomitant therapy such as rhDNase and inhaled antibiotics,” they point out.  “These results support the use of mannitol as an osmotic, inhalation dry powder treatment for the daily management of CF patients to improve overall pulmonary function with a shortened time of treatment burden,” they conclude.