Efficacy and safety of mixture of ivy leaf extract and coptidis rhizome in the treatment of acute bronchitis: multicenter, randomized, double-blinded, active-controlled, parallel, therapeutic confirmatory clinical trial

Background: Acute bronchitis is the most common respiratory disease. Mixture of Ivy Leaf Extract and Coptidis rhizome syrup has shown good treatment efficacy against chronic bronchitis and acute respiratory infections. This study aimed to evaluate the efficacy and safety of Mixture of Ivy Leaf Extract and Coptidis rhizome compared with those of Pelargonium sidoides extract, for the treatment of acute bronchitis. Methods: We performed a multicenter, randomized, double-blind, active-controlled, parallel phase III study in 220 patients with acute bronchitis. The participants were offered either Mixture of Ivy Leaf Extract and Coptidis rhizome syrup (AGS) and placebo of P. sidoides tablet or placebo syrup and active tablet of P. sidoides (AGU) for 7 days. The primary endpoint was the change in the Bronchitis Severity Score (BSS) from the baseline visit (visit 2) to day 7 (visit 3). Results: For the primary outcome, there was no significant difference in the change of total BSS between visits 2 and 3 (−4.10 ± 1.93 vs. −4.24 ± 1.85, p = 0.5125), and since the upper limit of the confidence interval (1.00) was smaller than the predetermined non-inferiority margin (1.17), it was confirmed that the AGS group was non-inferior to the AGU group. The changes in each symptom in the BSS between visits 2 and 3 also showed no significant differences. The overall improvement rate measured by the investigator (91.7 vs. 89.7%; p = 0.3506) and the satisfaction rate of the participants at visit 3 also showed no significant differences (97.2 vs. 94.4%; p = 0.4388). Regarding safety issues, adverse reactions were noted in both groups similarly, with no serious adverse events (4.55 vs. 3.64%, p > 0.999). Conclusion: Mixture of Ivy Leaf Extract and Coptidis rhizome syrup is as effective and safe as P. sidoides in controlling symptoms of acute bronchitis.