Aim: To assess the efficacy of smooth muscle relaxants in the treatment of patients with irritable bowel syndrome, a meta-analysis of 26 selected double-blind randomized trials vs. placebo was performed.
Methods: Five end-points were assessed: global assessment, abdominal pain, constipation, abdominal distension and the absence of adverse reactions. Analyses were performed according to the intention-to-treat method. For each end-point, the drug efficacy was assessed by the Der Simonian and Peto methods. When a significant difference was observed, sensitivity analyses were performed by successive stratifications according to the type of drug, the treatment duration, the prevalence of constipated patients, the trial design and the methodological quality.
Results: All myorelaxants analysed were significantly better than placebo for the improvement of global assessment (62% improvement rate vs. 35% on placebo, that is 27% improvement rate, P < 0.01) and for pain improvement (64% improvement rate vs. 45% on placebo, that is 19% improvement rate, P < 0.01). No significant differences were observed for constipation and abdominal distension. The percentage of patients with adverse reactions was significantly higher in patients receiving myorelaxants than placebo (6% mean difference, P < 0.01).
Conclusion: According to this overview five drugs have proved their clinical efficacy in patients with irritable bowel syndrome, without significant adverse reactions: cimetropium bromide, pinaverium bromide, trimebutine, octilium bromide and mebeverine.