An antibiotic can help some sufferers of irritable bowel syndrome, marking the first potential drug treatment for the disease which affects 30 million people in the United States, said a study.
The ailment causes bloating, abdominal pain, watery stool or constipation, and the findings in the New England Journal of Medicine appear to confirm studies in the past decade that suggest it is caused by bacteria in the gut.
"These results support the idea that intestinal microbiota or gut bacteria may be an underlying cause of IBS, and altering gut bacteria by treatment with rifaximin appears to be an effective way of providing relief to those who suffer from IBS symptoms," said co-author Yehuda Ringel.
The US Food and Drug Administration has already approved rifaximin, marketed as Xifaxan by Salix Pharmaceuticals, for treatment of travellers' diarrhoea.
According to Mark Pimentel, who headed clinical trials at Cedars-Sinai, some subjects in the study experienced pain relief for weeks after they stopped taking the antibiotic.
"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," Pimentel said.
"For years, the treatment options for IBS patients have been extremely limited," he added. "IBS often does not respond well to treatments currently available, such as dietary changes and fibre supplements alone."
The journal noted that Pimentel "discovered the use of rifaximin for IBS," and he is "a consultant to Salix, Inc, and serves on its scientific advisory board."
The drug maker provided funding for the study, hosted at five US medical facilities, which involved more than 600 IBS sufferers with mild to moderate diarrhoea and bloating.
The subjects were "randomly assigned to take a 550 milligram dose of rifaximin or placebo three times daily for two weeks. Study participants were then followed for 10 weeks more," it said.
40% of patients felt relief from symptoms after taking the antibiotic for two weeks.
In comparison, about 30% of those taking a placebo reported similar results.
"Patients reported relief from bloating, less abdominal pain and improved stool consistency for up to 10 weeks," the study said. (Sapa/January 2011)