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Ondansetron and metformin-induced gastrointestinal side effects

Hoffmann IS, Roa M, Torrico F, Cubeddu LX

American journal of therapeutics, 2003

98 participants

Abstract

Treatment with metformin is associated with a high incidence of gastrointestinal side effects of unknown mechanism. Metformin is a biguanide derivative, which resembles 5-HT3-receptor agonists in its structure. Activation of 5-HT3 receptors is known to induce nausea, vomiting, and diarrhea. In this study, we investigated if the gastrointestinal side effects produced by metformin were antagonized by ondansetron, a selective antagonist of 5-HT3 receptors. Patients experiencing gastrointestinal side effects were randomized to ondansetron (4 mg bid p.o.) or placebo while maintained on metformin (double-blind, parallel-group design). If side effects persisted or worsened, metformin was discontinued and the patient considered a therapeutic failure. Of the 98 subjects treated with metformin, 22 developed side effects to match the study entry criteria. Diarrhea was the most frequent side effect. Subjects were randomized to ondansetron (10/2 F/M, 42.8 +/- 2.3 years, 28.6 +/- 1.1 kg/m2, 2585 +/- 35 mg/d metformin) or placebo (9/1 F/M, 43 +/- 4.3 years, 29.7 +/- 1.8 kg/m2, 2715 +/- 71 mg/d metformin). Ondansetron showed no efficacy against metformin-induced side effects. A comparable number of therapeutic failures were observed in ondansetron (8/12; 66%) and placebo-treated subjects (5/10; 50%) (P0.1). In conclusion, 5-HT3 receptors do not seem to play a role in metformin-induced gastrointestinal side effects.

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 98 participants or records.

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