Azithromycin does not appear to be an effective agent for those with treatment-resistant cough, but may be useful in treating those with comorbid asthma, according to the results of a study published in Chest.

David Hodgson, Ph.D., from the Nottingham Respiratory Research Unit at the University of Nottingham (England), and colleagues conducted an 8-week randomized, double-blind, placebo-controlled parallel group trial with follow-up visits at 4, 8, and 12 weeks to determine whether treatment with low-dose azithromycin would affect the Leicester Cough Questionnaire (LCQ) score, cough severity on a visual analog scale, and fraction of exhaled nitric oxide (FENO) in patients with treatment-resistant chronic cough. (Chest. 2016 Apr;149[4]:1052-60. doi: 10.1016/j.chest.2015.12.036 ).

The study included 40 nonsmoking patients who were being investigated for chronic cough in respiratory clinics at Nottingham University Hospitals National Health Service Trust in the United Kingdom. Twenty patients were randomized to receive azithromycin capsules 500 mg daily for 3 days, followed by 250 mg three times a week for 8 weeks, and 20 received lactose-containing placebo capsules taken according to the same dosing schedule. The primary outcome measure was change from baseline in LCQ score at week 8.

The study results suggested differences in the primary endpoint in response to treatment with azithromycin; however, statistical significance was not detected after adjusting for baseline values. Ancillary analyses suggested that study subjects with asthma treated with azithromycin exhibited a large and statistically significant improvement in LCQ score when compared with those treated with placebo. This difference was detected at 4 weeks and was statistically significant at the end of the 8-week trial and at all follow-ups. There were no significant changes in FENO levels between any groups in this study, and treatment was considered to be well tolerated.

Based on their data, Dr. Hodgson and colleagues said that their results were not supportive of the routine use of low-dose macrolides in patients with treatment-resistant chronic cough. They also noted that data from their ancillary analyses were suggestive of an association between azithromycin treatment and improvement in LCQ in those with chronic cough and coexisting asthma that could be a focus of additional research.

Funding for this project was provided by a National Institute for Health Research Biomedical Research Fellowship. The authors reported no conflicts of interest.