DDW: Lubiprostone Effective in Irritable Bowel Syndrome

WASHINGTON, May 22 -- A drug approved for chronic constipation also appears to be effective to treat the condition when it is associated with irritable bowel syndrome (IBS-C), a researcher said here.But the benefit can be achieved with a dose of lubiprostone (Amitiza) that is a third of that needed to treat chronic constipation, according to Douglas Drossman, M.D., of the University of North Carolina in Chapel Hill.
The finding emerged from two industry-supported studies, involving 1,167 patients in 130 centers, Dr. Drossman said during Digestive Disease Week sessions.
The report came after Novartis halted sales on March 30 of tegaserod (Zelnorm), its agent for irritable bowel syndrome and constipation, following suggestions of a small increase in ischemic events, including angina and stroke, in those taking the drug.
Lubiprostone, a type-2 chloride channel activator, improved symptoms in phase II studies of patients with IBS-C, Dr. Drossman said.
He and colleagues conducted a parallel randomized, double-blind, placebo-controlled studies whose endpoint was significant or moderate improvement on a seven-point scale.
Patients were randomized to placebo or 8 mcg of lubiprostone twice daily. The recommended dose for chronic constipation is 24 mcg twice daily.
The combined studies found that patients getting lubiprostone were nearly twice as likely to achieve overall response. It was 17% for the medication, compared with 10.1% for placebo - a difference that was significant at P=0.001.
Individually, each study also showed a significant benefit for lubiprostone, at P=0.009 and P=0.031.
The drug was well-tolerated, Dr. Drossman said, with a similar rate of serious adverse events in treatment and placebo arms. The most common treatment-related adverse effects were nausea (8% for lubiprostone versus 4% for placebo) and diarrhea (6% versus 4%, respectively).
The findings suggest "we can get benefit for pain in the lower dose, while still achieving benefit in terms of constipation" Dr. Drossman said.
The studies add to the weapons a doctor can deploy to aid patients with the condition, commented Maria Abreu, M.D., of Mount Sinai in New York, who moderated a press conference where they were discussed.
"It's a big group of people and a group of people who are miserable," said Dr. Abreu, who was not involved in the research.
IBS-C poses "very vexing problems," Dr. Abreu said, because the most unpleasant symptom is pain, which is hard to quantify.
In this study, she said, "the absolute difference between placebo and response seems very small but you have to take into account that there's no objective criteria for pain."
The bottom line, Dr. Abreu said, is "I would use it as first-line therapy for some patients with constipation-predominant IBS, on the basis of these studies."