Many people with the bloating, cramping, abdominal pain and constipation associated with irritable bowel syndrome (IBS) may find relief in the IBS drug lubiprostone (Amitiza).

In clinical trials leading up to the drug’s April 2008 FDA approval, University of Michigan Health System researchers found that individuals who were treated with Amitiza were nearly twice as likely to experience improvement in their IBS symptoms compared to individuals who were treated with placebo, says lead author William D. Chey, MD.  “Right now, it is the only FDA-approved treatment available that addresses the entire clinical spectrum of symptoms related to IBS [with constipation],” he says.

IBS, an often-painful disorder of the lower intestine, affects 10 percent to 15 percent of the U.S. population, mostly women. Most patients with IBS tend to fall into two categories: IBS with constipation (IBS-C) or IBS with diarrhea (IBS-D). IBS-C is more common among older adults, while IBS-D tends to be seen more in younger patients.

Amitiza is currently approved only for women, simply because the majority of patients with IBS – and, therefore, the majority of study subjects – are women. But that doesn’t mean the drug doesn’t work for men, says Dr. Chey. “Unfortunately, we just haven’t had enough men represented in these studies to make a firm decision on treatment using this drug.”