Efficacy and safety of Tanreqing oral liquid in treatment of acute bronchitis: study protocol for a randomized controlled trial

BACKGROUND: Approximately 5% of adults have an episode of acute bronchitis each year, accounting for more than 10 million medical visits yearly. The primary goal of treatment is reduction of symptoms. Currently, available medications are questionable in effectiveness and safety and are not recommended for routine use in clinical practice. Although Chinese herbal medicine has been widely used in the management of acute bronchitis in China, evidence-based data is lacking. This trial aims to evaluate the efficacy and safety of Tanreqing oral liquid in the treatment of acute bronchitis with phlegm-heat obstructing lungs syndrome. METHODS/DESIGN: This study is a prospective, multi-center, randomized, double-blinded, parallel-group, placebo-controlled trial. A total of 270 acute bronchitis adult patients with phlegm-heat obstructing lungs syndrome will be enrolled from outpatients and emergency departments at nine study centers across China. All included patients will be randomly allocated to receive Tanreqing oral liquid or placebo oral liquid, 20 mL three times daily for seven consecutive days. The primary outcome will be cough resolution rate. Secondary outcomes will include change of bronchitis symptoms scores from baseline to post-treatment, cough relief rate, time to cough resolution, time to cough relief, resolution rate of a single symptom, combination medicine use, change of traditional Chinese medicine syndrome score from baseline to post-treatment, and adverse events. DISCUSSION: This trial may provide an alternative treatment option for acute bronchitis patients, especially those in outpatients and emergency departments. It may also add evidence to Chinese herbal medicine for treating acute bronchitis. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2000040264. Registered on 26 November 2020 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06318-5.