Comparison of efficacy and safety of hyoscine butylbromide versus anisodamine for acute gastric or intestinal spasm-like pain: a randomized, double-blind and multi-center Phase III trial.

OBJECTIVE: Acute gastric or intestinal spasm-like pain is common in clinical setting. Hyoscine butylbromide (HBB), an anti-cholinergic agent, relieves pain in stomach and bowel cramps by inhibiting smooth muscle contractility. In this study, we aimed to compare the efficacy and safety of parenteral HBB and anisodamine for treating acute gastric or intestinal pain. METHODS: In this randomized, controlled, double-blind, parallel-group, multicenter non-inferiority trial, 299 Chinese patients were randomly assigned to HBB or anisodamine in a ratio of 1:1. They were administrated a single dose of either HBB 20 mg or anisodamine 10 mg, and a second dose was given when needed. The primary end-point was the difference in pain intensity (PID) from the pre-dose baseline at 20 min after the first injection. RESULTS: Altogether 295 patients completed the protocol (153 in the HBB and 142 in the anisodamine group). For the primary end-point, the PID was -4.09 (95% confidence interval [CI]: -4.41, -3.76) for the HBB group and -3.66 (95% CI: -4.02, -3.31) for the anisodamine group (P < 0.0001 for non-inferiority). The percentage of patients with at least one adverse event was lower in the HBB group than in the anisodamine group (13.1% vs 17.6%), but there was no statistical significance (P = 0.279). The most frequent adverse events were thirst (7.8%) and dry mouth (2.6%) in the HBB group, and thirst (7.0%), dry mouth (3.5%) and nodal arrhythmia (2.1%) in the anisodamine group. CONCLUSIONS: HBB 20 mg was not inferior to anisodamine 10 mg in pain relief of patients with acute gastric or intestinal spasm-like pain. Both drugs were safe and well tolerated.