Antibiotic provides sustained relief for patients with IBS

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By Greg Town [source: MIMs]

Rifaximin, an oral non-systemic broad-spectrum antibiotic, provides long-lasting relief of irritable bowel syndrome (IBS) symptoms, according to new research. Combined data from the two identically designed phase III TARGET* studies (TARGET 1 and TARGET 2), which involved a total 1,260 patients with IBS without constipation, showed that 2 weeks of treatment with rifaximin significantly reduced rates of IBS symptoms, such as bloating, abdominal pain and watery stools, for up to 4 weeks post-treatment, compared with placebo. Adverse event rates were comparable between the treatment groups. [NEJM 2011;364:22-32] The results of this study demonstrate that targeted antibiotics can be safe and effective in providing long-term relief for patients with IBS, said principal investigator Dr. Mark Pimentel, director of the GI Motility Program at Cedars-Sinai Medical Center, Los Angeles, California, US. For years, the treatment options for IBS patients have been extremely limited. IBS often does not respond well to treatments currently available, such as dietary changes and fiber supplements alone. With this antibiotic treatment, the patients feel better, and they continue to feel better after stopping the drug. This means that we did something to strike at the cause of the disease.” In each of the TARGET 1 and TARGET 2 trials, patients were randomized in a double-blind fashion to receive either rifaximin 550 mg or placebo three times daily for 2 weeks and were then followed-up for 10 weeks. In the two studies combined, 40.7 percent of patients receiving rifaximin had adequate relief of global IBS symptoms during the first 4 weeks after treatment compared with 31.7 percent of placebo recipients (P<0.001). Likewise, significantly more patients from both studies receiving rifaximin had adequate relief from bloating versus those receiving placebo (40.2 percent vs. 30.3 percent, respectively; P<0.001). In an accompanying editorial, [NEJM 2011;364:81-82] Dr. Jan Tack from the department of pathophysiology at the Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium, writes that: “The TARGET studies have some attractive findings. First, the sustained benefit over at least 10 weeks, after a short treatment course, is appealing. Second, the beneficial effects of rifaximin include its effects on bloating, which is one of the most challenging symptoms of IBS. Third, the similarity of the results in both studies confirms the reproducibility of the therapeutic effect.” Tack suggested these latest findings are very promising. “Rifaximin has the potential to provide a welcome addition to the limited armamentarium of agents that are available to treat IBS.” However, he advised that clinicians proceed with caution. “IBS is a chronic condition, and some regulatory authorities recommend that studies be conducted that will address the efficacy of rifaximin when it is used for continued or intermittent treatment of IBS… and this seems to be even more appropriate in the case of antibiotic therapy that may have a risk of inducing resistance over time.” “Studies aimed at better identifying the patients with IBS who may have a response to rifaximin and, especially, studies that will assess the longer-term effect of rifaximin treatment are eagerly awaited,” concluded Tack. – GT

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