Despite the relatively small percentage of patients who responded to the drug, doctors who have been frustrated by the lack of effective IBS treatments say they would welcome another option.
Charlene Prather, MD, a professor of internal medicine at Saint Louis University, in Missouri, says that while she’d hoped to see a “more robust effect” from rifaximin in the studies, she nevertheless would like the FDA to approve the drug for IBS. “It still provides me with something I can offer my patients,” says Dr. Prather, who was not involved in the new research.
Currently, “there are no good options” for treating IBS, says Timothy Pfanner, MD, a gastroenterologist and assistant professor of internal medicine at Texas A&M Health Science Center, in Temple. Rifaximin may benefit a subgroup of patients with IBS, Dr. Pfanner says, although he stresses that most people in the study did not experience relief from their symptoms.
“As a doctor, I’d need to treat 10 patients for one to improve,” he adds.
Rifaximin would be the first antibiotic approved by the FDA for the treatment of IBS. Aside from providing evidence of the drug’s effectiveness, the study findings—especially with regard to bloating—support the theory that bacteria may be partially responsible for IBS.
Bloating is sometimes thought to be related to bacterial imbalances in the gut, and antibiotics are a class of drugs that work only against bacteria. “That suggests that we hit upon a cause of IBS,” Dr. Pimentel says.
This theory is still controversial. Dr. Prather says that while there is some evidence to suggest that bacteria plays a role in IBS, it’s unclear whether changes in gut bacteria are a cause or an effect of the syndrome.