Some drugs less harsh than others for IBS


A new meta-analysis suggests that certain drugs used to treat irritable bowel syndrome (IBS) may have fewer side effects.

The new findings are based on 26 studies that compared benefits and harms of drugs used to treat IBS with and without diarrhoea.

"We do know that a lot of these drugs have side effects," said Dr Mark Pimentel, the study's lead author and director of the Cedars-Sinai Medical Centre’s Gastrointestinal Motility Programme in Los Angeles.

"They've been reported, but we didn't realise how bad it actually was – specifically in the IBS population."

Side effects include dry mouth

For patients with diarrhoea, the authors looked at studies of tricyclic antidepressants, alosetron (which slows GI motility and allows stool to absorb more water), and the antibiotic rifaximin.

From 19 studies, the researchers determined that about two people would benefit from tricyclic antidepressants before one patient was harmed, on average. About three patients would benefit from alosetron before one patient experienced harm, and 846 would benefit from rifaximin before one is harmed.

Without looking at how many patients would benefit, the numbers needed to harm for tricyclic antidepressants, alosetron, and rifaximin were 18.3, 19.4, and 8,971, respectively. The numbers needed to treat were 8.0, 7.5, and 10.6, respectively.

Side effects generally included dry mouth, flushing, palpitations, insomnia, constipation, stomach pain and other mild to serious symptoms.

Safety of antibiotics unknown

Alosetron, however, was withdrawn from the market in the US from 2000 to 2002 because of its potential to cause ischemic colitis, perforation, impaction, toxic megacolon, and death.

While rifaximin appears to be the safest option for IBS patients, Dr Ira Breite, a gastroenterologist at the New York University Langone Medical Centre, said the study didn't answer one important question about the drug.

Dr Breite, who was not involved in the new research, told Reuters Health that even if rifaximin is safe during treatment, nobody knows the safety of long-term use of antibiotics and what happens when you keep giving them.

Approach to IBS treatment won’t change

As for IBS with constipation, the group did not have as much information to work with and it was hard to draw definitive conclusions, Dr Pimentel told Reuters Health.

But the team wrote online in The American Journal of Medicine that selective serotonin reuptake inhibitors and the prostaglandin E1 derivative lubiprostone "seem safe."

"This is not going to change any doctor's current approach to treating IBS," said Dr Breite, who added that it confirmed what physicians have thought.

(Andrew M. Seaman, Reuters Health, March 2012) 

Read more:

The real reason for IBS

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