Results from two randomized, placebo-controlled trials reported in the New England Journal of Medicine of January 6, 2011, showed that treatment with rifaximin for two weeks resulted in significant symptom reduction and long-term improvement the condition of patients with the syndrome. irritable bowel (IBS).

Until recently, treatment options for IBS patients were very limited. In many patients, it was not possible to achieve a positive effect by changing the diet or by prescribing dietary fiber. After treatment with rifaximin, patients noted a significant decrease in IBS symptoms, and the improvement achieved continued for a long time after stopping the antibiotic. This means that scientists have finally found an opportunity to influence the cause of IBS.

The theory of the role of the intestinal microflora in the development of irritable bowel syndrome has been known for a long time. However, the opinions of scientists on the use of antibiotics and the choice of an antimicrobial drug for the treatment of IBS were very divided. Rifaximin is an antibiotic from the rifamycin group, which is minimally absorbed when taken orally. Rifaximin is currently approved by the United States Food and Drug Administration (FDA) for the treatment of traveler's diarrhea and hepatic encephalopathy.

The use of rifaximin in patients with IBS has been studied in two identical placebo-controlled randomized trials of the third phase, TARGET 1 and TARGET 2. The study involved 1,260 patients diagnosed with IBS, established at during the previous 2 years on the basis of a colonoscopy. The average age of the participants was 46 years, almost three quarters of the patients were women.

Patients were randomly assigned to treatment with rifaximin at a dose of 550 mg 3 times a day orally or in a placebo group. The duration of treatment in the study was 2 weeks, after which the patients were observed for 10 weeks. The condition was assessed weekly, while the proportion of patients with marked improvement in general health (based on patients' overall assessment of IBS symptoms) and with a significant reduction in bloating associated with IBS was calculated. Patients assessed their condition daily using the "Common IBS Symptom Rating Scale" and an improvement in this score was used as a criterion for patients to respond to treatment. In addition, throughout the study (three months), patients assessed changes in individual IBS symptoms, such as bloating, abdominal pain, and stool consistency.

In the first 4 weeks after treatment in the rifaximin treatment group, improvement was noted in 40.8% and 40.6% of patients, and in the placebo group - in 31.2% and 32.2 % patients; p = 0.01 and p = 0.03 in the TARGET 1 and TARGET 2 studies, respectively. In a combined analysis of the data, the corresponding indicators were 40.7% vs 31.7%; p is less than 0.001. The rifaximin treatment group also showed a more pronounced reduction in bloating than with a placebo: 39.5% vs 28.7%; p = 0.005 in the TARGET 1 study; 41.0% vs 31.9%; p = 0.02 in the TARGET 2 study; 40.2% vs 30.3%; p less than 0.001 when analyzing the combined results of the two studies. In addition, with rifaximin treatment, the severity of other IBS symptoms - abdominal pain and loose stools - decreased. Patient compliance with the study was high. The incidence of adverse events did not differ between the groups, cases of ischemic colitis and C. no diarrhea associated with difficult was noted. The maximum effect of rifaximin treatment was observed after 2 weeks of treatment, after which it gradually decreased over 10 weeks of subsequent observation.

Studies have shown the benefits of rifaximin compared to placebo in the treatment of IBS patients. However, further research should be aimed at identifying subgroups of IBS patients who can expect maximum benefit from the use of antibiotics (for example, patients with markedly excessive growth of bacteria in the small intestine). In addition, the potential risk of selecting antibiotic resistant bacterial strains in the event of frequent use of antibiotics for IBS should be taken into account.