Mannitol is a naturally occurring sugar that is available as a dry powder. When inhaled, it works in two ways in the lungs, as an osmotic agent that rehydrates mucus and changes the properties of the bronchi walls, and as an agent that enhances airway clearance by improving the interaction between cilia and mucus.

Osmotic agents such as mannitol have the capacity to draw water from inside cells to the outside, and vice-versa. In this specific case, inhaled mannitol increases the sugar levels in mucus, a change that draws water from lung cells in response, rehydrating mucus. As mucus becomes more hydrated, its interaction with cilia increases, making it easier to cough from the lungs.

Mannitol (brand name, Aridol) is approved as a clinical test of bronchial hyperresponsiveness in people suspected of having asthma.

Studies of inhaled mannitol for bronchiectasis

Previous studies of inhaled mannitol have demonstrated improvement in airway clearance, mucus rehydration, quality of life and respiratory symptoms in people with bronchiectasis.

A Phase 3 study (NCT00669331) assessed the safety and efficacy of 400 mg of inhaled mannitol twice daily for 12 months in 485 people with non-cystic fibrosis bronchiectasis, compared to 50 mg of inhaled mannitol twice daily given a control group.

Published results found no significant reduction in the number of exacerbations in patients using 400 mg of inhaled mannitol compared to low-dose controls. However, time to first exacerbation improved in high-dose patients as did  their quality of life, as measured by the St. Georges Respiratory Questionnaire (SGRQ). Adverse events were similar between the two groups, and inhaled mannitol at both levels was found to be safe and well-tolerated.

An earlier study conducted in Australia concluded that this treatment has the potential to “minimize retention of mucus” and help bronchiectasis patients “who require a daily intervention to clear their secretions.”


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