Efficacy of Rifaximin for the Treatment of Symptoms Associated with Irritable Bowel Syndrome

Abstract

Purpose: Emerging evidence suggests that intestinal bacteria, including small intestinal bacterial overgrowth, may play an important role in the pathophysiology of irritable bowel syndrome (IBS) and that antibiotic treatment may have therapeutic benefits for patients experiencing IBS symptoms. Rifaximin is a nonabsorbed antibiotic with minimal systemic absorption (<0.4%) and broad-spectrum activity against intestinal pathogens. Results from clinical studies suggest that rifaximin may improve gastrointestinal (GI) symptoms associated with IBS. This retrospective chart review evaluated the efficacy of rifaximin alone or in combination with other IBS treatments for improving IBS symptoms. Methods: Medical records were identified for consecutive adults with IBS who had lactulose breath tests between October 2006 and July 2007. Analyses included those who had received rifaximin 400 mg three times daily for 10 days. Global symptom improvement and improvement in specific IBS symptoms were evaluated. Results: Of the 159 patients (mean age, 58 y) included, 44 (28%) were diagnosed with diarrhea-predominant IBS (IBS-D), 33 (21%) with constipation-predominant IBS (IBS-C), and 24 (15%) with alternating IBS; 58 patients (36%) had no reported IBS subtype diagnosis. Baseline symptoms included abdominal pain (N = 83; 52%), bloating (N = 114; 72%), constipation (N = 79; 50%), diarrhea (N = 97; 61%), and gas (N = 118; 74%). During rifaximin treatment, 76 patients (48%) received concomitant treatment with other antibiotics, tegaserod, or probiotics. Of the 118 patients for whom percentage global improvement was reported, 65 (55%) achieved ≥ 50% improvement and 21 (18%) had ≥ 90% improvement at the first follow-up visit within approximately 1 month of completing rifaximin treatment. The mean percentage global improvement after rifaximin treatment was 45%. At follow-up, ≥ 50% improvement of abdominal pain, bloating, constipation, diarrhea, and gas was reported in 16%, 12%, 10%, 15%, and 11%, respectively, of patients who reported the specific symptom at baseline. The percentage of patients with ≥ 50% improvement in the predominant GI symptom after rifaximin treatment was higher for patients with IBS-D versus IBS-C. Similarly, among patients with available global improvement data, those with IBS-D reported a higher percentage mean global improvement after rifaximin treatment compared with patients with IBS-C (55% vs 34%). Rifaximin was generally well tolerated. Conclusion: These findings suggest that rifaximin 1200 mg/d administered for 10 days alone or in combination with other IBS treatments improved GI symptoms in patients with IBS and support the potential therapeutic benefit of rifaximin for the treatment of IBS.