Efficacy and safety of Maekmoondong-tang for chronic dry cough: a study protocol for a randomized controlled trial.

BACKGROUND: Chronic cough, defined it lasts more than 8 weeks. The symptom is common, but highly troublesome, and it reduces quality of life. Despite much effort to develop a protocol for diagnosis and treatment of chronic cough, it remains problematic to determine its cause. As a result, treatment is often unsuccessful. Thus, there is much interest regarding the use of symptomatic drugs to control chronic cough. Maekmoondong-tang is widely used in East Asian countries to treat chronic dry cough. Several experimental studies have reported that the herbal medicine has immunomodulatory and antitussive effects. Clinical studies involving Maekmoondong-tang have also been carried out; however, these studies have involved treating various diseases as a whole rather than chronic cough itself. Thus, we aim to evaluate the efficacy and safety of Maekmoondong-tang in chronic dry cough patients with a randomized controlled trial. METHODS/DESIGN: This study is designed as an exploratory, single-center, placebo-controlled, double-blind, randomized, parallel group clinical trial. Patients with dry cough that has lasted more than 8 weeks will be recruited, after a 1-week run-in period, and randomly allocated to either the Maekmoondong-tang treatment group or the placebo group. The patients will receive Maekmoondong-tang or placebo granules 3 times daily for 4 weeks, with a 2-week follow-up. The primary outcome is a 10-point cough diary that will be recorded on a daily basis. The secondary outcomes comprise a cough visual analog scale, the Leicester Cough Questionnaire (Korean version), the Pattern Identification for Chronic Cough Questionnaire, biomarkers, safety testing, etc. Adverse events will also be reported. DISCUSSION: This trial will assess the efficacy and safety of Maekmoondong-tang in chronic dry cough. TRIAL REGISTRATION: Korean Clinical Trial Registry ( http://cris.nih.go.kr ; registration number: KCT0001646). Date of registration: October 5 2015.