Effectiveness and safety of Suhuang Zhike capsules in adults with asthma: A multicenter, randomized, double-blinded, placebo-controlled trial

Suhuang Zhike (SHZK) Capsules are a traditional Chinese medicine formulation that are widely used to treat post-infectious cough. However, evidence supporting their efficacy in anti-asthmatic treatment and asthma-related cough remains limited. This study aimed to evaluate the efficacy and safety of SHZK in patients with inadequately or poorly controlled mild-to-moderate asthma and explore its potential mechanisms in asthma mouse models. A multicenter, randomized, double-blind, placebo-controlled trial was conducted with 132 participants (Asthma Control Test [ACT]≤19) from three hospitals. Patients were randomly assigned to receive either SHZK or a placebo for 14 days, alongside inhaled corticosteroids (ICS) and long-acting β2 agonists (LABA), followed by a 28-day follow-up. The mouse model of asthma was used to investigate SHZK's potential mechanisms. Although the SHZK group did not achieve statistically significant improvement in the ACT scores across the overall population, a statistically significant difference was observed in a specific subgroup of patients who had stable treatment prior to enrollment. SHZK also led to a more substantial and persistent reduction in cough-related visual analog scale scores, and had a significantly higher cough relief rate. SHZK significantly reduced blood eosinophils, immunoglobulin E, and major basic protein levels compared to the placebo. SHZK improved small airway function. The safety profiles were similar between groups. Animal experiments further confirmed the synergistic effects of SHZK in reducing airway inflammation, mucus secretion, and collagen deposition. SHZK capsules could be an effective and safety adjunct therapy to improve asthma control and reduce cough symptoms in patients with poorly controlled, mild-to-moderate asthma.