Efficacy and safety of HL-301 compared with erdosteine in acute bronchitis: a randomized, double-blind, non-inferiority trial

Background/Aims: This study evaluated the non-inferiority of HL-301 to erdosteine in terms of symptom relief and the anti-inflammatory effects in acute bronchitis patients not treated with antibiotics. Methods: In a double-blind, non-inferiority trial, patients were randomized 1:1 to receive either HL-301 (300 mg twice daily) or erdosteine (300 mg three times daily) for seven days. The primary endpoint was change in total Bronchitis Severity Score (BSS) from baseline to day 7. The non-inferiority margin was set at-0.99 for the difference in BSS change. The secondary endpoints were changes in specific symptoms, overall improvement, patient satisfaction, and inflammatory markers. Results: Mean BSS reduction at day 7 was-4.43 in the HL-301 group (n = 53) and-4.33 in the erdosteine group (n = 52). The difference in mean BSS change between the groups was 0.11, with the lower limit of the 97.5% one-sided confidence interval at-0.42, confirming non-inferiority. The improvement in specific symptoms, overall improvement, and patient satisfaction were high in both groups; however, there were no significant differences between the groups. Additionally, the changes in C-reactive protein, tumor necrosis factor-alpha, interleukin (IL)-1β, and IL-6 were similar between the groups, with no significant differences observed. The incidence of adverse events was higher in the HL-301 group compared to the erdosteine group, including gastrointestinal disorder, periodontitis, and increased blood cholesterol, although this difference was not statistically significant. Conclusions: HL-301 was non-inferior to erdosteine, confirming its positive effect on symptom relief in acute bronchitis patients managed with conservative care.