Rifaximin, a poorly absorbed broad-spectrum antibiotic, ameliorates the symptoms of irritable bowel syndrome, according to a phase III study published in the New England Journal of Medicine.
Researchers, including employees of the drug’s manufacturer, randomized some 1250 patients with irritable bowel syndrome (without constipation symptoms) to receive 2 weeks’ double-blind treatment with either a placebo or rifaximin.
In the first 4 weeks’ posttreatment, the rifaximin group reported greater relief of global IBS symptoms (41% vs. 32%) and greater relief of bloating (40% vs. 30%). Between-group differences remained throughout a 10-week monitoring period, although the beneficial effect declined over time.
An editorialist calls the therapeutic gain of roughly 10% to be “in the lower spectrum of what is considered to be clinically relevant.” Further, he advises restricting use of nonabsorbable antibiotics “to patients in whom small-intestine bacterial overgrowth has been confirmed” and in those unresponsive to other therapies.
