Efficacy and tolerability of renzapride in irritable bowel syndrome: a meta-analysis of randomized, controlled clinical trials including 2528 patients

INTRODUCTION: By targeting different subtypes of 5-hydroxytryptamine (5HT) receptors in the gastrointestinal (GI) tract, several drugs have been introduced for the management of irritable bowel syndrome (IBS). Renzapride is a full agonist for 5HT4 receptor and an antagonist to 5HT2b and 5HT3 receptors which is thought a promising therapeutic agent for constipation predominant IBS (C-IBS) patients due to its accelerating effect on the GI tract. In this meta-analysis, our aim was to evaluate the efficacy and tolerability of renzapride in the management of IBS. MATERIAL AND METHODS: A search was done from 1992 to February 2013 for placebo-controlled trials that investigated the efficacy of renzapride in IBS. RESULTS: Relative risk (RR) for clinical efficacy in IBS patients treated for 5 weeks or less comparing renzapride to placebo was 1.07 (95% CI = 0.89–1.29, p = 0.38). This value for IBS patients treated for more than 5 weeks was 1.04 (95% CI = 0.78–1.239, p = 0.77). The RR for clinical efficacy in IBS patients treated with renzapride (4 mg) for 5 weeks or less and more than 5 weeks in comparison to placebo was 1.2 (95% CI = 0.97–1.48, p = 0.1) and 1.16 (95% CI = 0.98–1.37, p = 0.08), respectively, which were statistically non-significant but clinically important. The analysis of tolerability demonstrated that amongst different reported adverse effects, renzapride caused diarrhea more than placebo (RR = 1.61 with a 95% CI = 1.16–2.24, p = 0.004). The RR for withdrawals from renzapride compared to placebo was 1.58 (95% CI = 1.26–2.07, p = 0.0007). CONCLUSIONS: Renzapride is not superior to placebo in relieving IBS symptoms and causes significant incidences of diarrhea and drop-outs due to adverse effects in treated patients vs. placebo. Thus, this medicine might be a cost burden to patients without providing good effectiveness.