Bronchitol (mannitol) by Pharmaxis is a dry powder inhalation treatment for people with cystic fibrosis (CF).
How does Bronchitol work?
CF is a heritable disease caused by mutations in the CFTR gene. This gene encodes for a protein that channels salts through cell membranes. Mutations in the gene cause cells to make the CFTR protein incorrectly, resulting in poor salt transport at the cell membrane and the buildup of thick mucus in different organs and tissues.
People with CF often have difficulty breathing because of this mucus accumulating in their lungs. They are also more prone to respiratory infections.
Although the exact mechanism of action for Bronchitol is not known, the therapy’s active ingredient, mannitol, is a small molecule that attracts water. Researchers think that mannitol draws water into the airways, moistening and thinning the sticky mucus to make it easier for patients to cough it out, aiding lung function.
Bronchitol in clinical trials
Pharmaxis investigated the safety and efficacy of Bronchitol for CF in three Phase 3 clinical trials.
In the first trial (NCT 00630812), researchers randomly assigned 318 CF patients, ages 6 and up, to either 400 mg or 50 mg of Bronchitol given twice a day for 26 weeks. The trial then continued with an open-label extension phase, in which all enrolled were given the treatment at 400 mg for 26 weeks.
Study results showed that the treatment improved FEV1 (forced expiratory volume in one second), a measure of lung health. Participants taking 400 mg of Bronchitol twice a day had an 8.2% improvement in FEV1 compared to their initial measurements, and by 3.75% compared with patients initially given the low dose as a control group.
The second trial (NCT00446680) included 324 CF patients, ages 6 and up, who randomly received 400 mg of Bronchitol twice per day or a placebo for 26 weeks. A 26-week open-label treatment phase then followed.
Results showed an FEV1 improvement of 6.5% in Bronchitol-treated patients compared with 2.4% in those in the placebo group. Improvements in FEV1 were maintained for up to 52 weeks in the open-label portion of the study. There was also a 35.4% reduction in pulmonary exacerbations (when lung symptoms worsen) in the treatment group.
A third trial (NCT02134353) enrolled 423 adults with CF, randomly given Bronchitol at either 400 mg or 50 mg twice daily for 26 weeks.
Here, results showed that higher dose treatment resulted in an average increase of 1.6% in FEV1. This was significantly greater than the 0.39% increase in those receiving the lower dose. Other measures of lung function also favored the higher dose.
Safety data were largely consistent across the three trials. Adverse events were at similar rates among patients who received active treatment with Bronchitol and those assigned to a control group (given a placebo or lower doses of the therapy). Most adverse events were mild to moderate in severity.
Common side effects of Bronchitol include coughing and bronchospasm (a narrowing of the airways) during treatment, hemoptysis (coughing up blood), throat pain, vomiting, fever, and joint pain.
Chiesi USA is distributing Bronchitol in the U.S. and to 11 countries in Europe.
Last updated: March 22, 2021
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