Bronchitol (mannitol) is a dry powder for inhalation that is used to treat cystic fibrosis (CF). Developed by Pharmaxis, it has been approved for the treatment of CF in patients, age 6 and older in Australia, and age 18 and older in the E.U. and Israel.
The treatment has not yet been approved in the U.S. but Pharmaxis submitted a new drug application to the U.S. Food and Drug Administration with the results of the most recent clinical trial testing Bronchitol. A decision is expected in late 2019 or early 2020.
How Bronchitol works
CF is a heritable disease caused by mutations in the CFTR gene, which encodes for a protein that channels salts through cellular membranes. Mutations in CFTR cause the protein to be made incorrectly, resulting in poor salt transport at the cell membrane, and the buildup of thick mucus in different organs and tissues.
Patients with CF often have difficulty breathing because of this mucus accumulating in their lungs, and are more prone to respiratory infections.
Bronchitol is designed to be used as an inhaled powder. Mannitol, its active ingredient, is a small molecule that attracts water. In the lungs, it draws water into the airways, moistening and thinning the sticky mucus, which makes it easier for patients to cough out.
Bronchitol in clinical trials
A Phase 3 clinical trial (NCT 00630812) to assess long-term improvements in lung function in CF patients treated with Bronchitol has been completed. Patients were randomly assigned to receive 400 mg of Bronchitol (192 patients) or 50 mg of Bronchitol (126 patients) twice a day. All patients were treated for 26 weeks in a double-blind study, followed by an open-label treatment for an additional 26 weeks.
The results were published in the American Journal of Respiratory and Critical Care Medicine and demonstrated that patients treated with Bronchitol showed an improvement in lung capacity as measured by FEV1 (forced expiratory volume in one second). Patients taking 400 mg of Bronchitol twice a day improved FEV1 by 8.2 percent compared with their initial measurements, and by 3.75 percent when compared with patients receiving the low dose. Side effects were similar in both groups.
Another Phase 3 clinical trial (NCT00446680) assessing the efficacy and safety of long-term treatment with Bronchitol included 324 CF patients, 6 years and older, who were randomly assigned to be treated with 400 mg of Bronchitol twice per day or a placebo for 26 weeks in a double-blind study followed by 26 weeks of open-label treatment.
The results, published in the European Respiratory Journal, showed an improvement of 6.5 percent in FEV1 in patients treated with Bronchitol compared with 2.4 percent 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 percent reduction in lung exacerbations (respiratory infections leading to worsening of lung function) in the treatment group. The incidence of side effects was similar for both groups.
A Phase 3 clinical trial (NCT02134353) to assess the safety and efficacy of Bronchitol in CF patients has been completed. It included 423 adult patients who were randomly assigned to receive 400 mg of Bronchitol twice daily or a placebo for 26 weeks. Patients receiving Bronchitol had improved FEV1. The number and severity of side effects were similar between the treatment and placebo groups.
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