Scientists have found that a drug commonly used to treat chronic obstructive pulmonary disease (COPD) could also be used for the treatment of adults whose asthma is not well-controlled on low doses of inhaled corticosteroids.
Researchers supported by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health, conducted the study.
"This study's results show that tiotropium bromide might provide an alternative to other asthma treatments, expanding options available to patients for controlling their asthma," said Susan B. Shurin of National Heart, Lung, and Blood Institute (NHLBI).
According to the study, adding tiotropium bromide to low doses of inhaled corticosteroids is more effective at controlling asthma than doubling inhaled corticosteroids alone, and as effective as adding the long-acting beta agonist salmeterol.
Higher doses of corticosteroids do not improve symptoms for all patients and can have significant side effects, while long-acting beta agonists have come under scrutiny for their risk of worsening asthma symptoms that could result in hospitalization and, rarely, death.
"Tiotropium relaxes smooth muscle in the airways through a different mechanism than beta agonists, and thus may help people who do not respond well to currently recommended treatments," said study lead Stephen Peters of Wake Forest University Baptist Medical Center.
"Further analysis of the study data will help us better understand which patients respond best to tiotropium. Then we will need to conduct longer-term studies to establish its safety for asthma patients and to determine its effect on the frequency and severity of asthma exacerbations," he said.
Conducted by the NHLBI's Asthma Clinical Research Network, the study compared three treatment methods: doubling the dose of inhaled corticosteroids alone, supplementing a low dose of inhaled corticosteroids with a long-acting beta agonist (salmeterol), and supplementing a low dose of inhaled corticosteroids with a long-acting anticholinergic drug (tiotropium bromide).
The study followed 210 adults whose asthma was not well-controlled on low doses of inhaled corticosteroids alone. Participants received each treatment for 14 weeks with two-week breaks in between, for a total of 48 weeks.
Tiotropium bromide was shown to be effective using several asthma control measurements, including patients' day-to-day lung function as well as the number of days in which they had no asthma symptoms and did not need to use their albuterol rescue inhalers.
When patients began the trial, their average number of such "asthma control days" was 77 per year (extrapolated from the treatment period).
Doubling corticosteroids gave patients another 19 symptom-free days on average, while adding tiotropium to low-dose corticosteroids gave them another 48.
The findings were published in the New England Journal of Medicine and presented at the Annual Congress of the European Respiratory Society in Barcelona.
