WASHINGTON -- Millions of women who suffer irritable bowel syndrome won a new treatment Wednesday that promises some relief for their diarrhea and pain.
The Food and Drug Administration approved Lotronex, the first new therapy in years for the mysterious intestinal disorder. The FDA cautions that the drug offers modest help and is not a cure.
Irritable bowel syndrome, or IBS, involves chronic or recurrent abdominal pain, the sudden and urgent need to go to the bathroom, and frequent diarrhea or constipation. It affects up to 15 percent of the U.S. population, and is three times more common in women than men.
Lotronex, known chemically as alosetron, is only for women who have diarrhea-prone IBS. Studies so far show no effect in men, or in women whose IBS is more prone to constipation than diarrhea, the FDA said.
Lotronex seems to work by blocking certain neurologic receptors that line the intestine, explained Dr. Victor Raczowski, FDA's deputy chief of gastrointestinal drugs. Those receptors affect pain sensations, fluid secretions and how rapidly waste moves through the intestines. By blocking those receptors, Lotronex theoretically offers a three-pronged attack against the pain and diarrhea of IBS.
In clinical trials involving 1,200 women, Lotronex had "a modest but real effect," Raczowski said. Of every 100 patients using it, about 10 to 15 got relief from abdominal pain and diarrhea, he said.
But even that modest effect is important because there are few other drugs that treat IBS and the illness can severely disrupt people's lives, he said.
The main side effect was constipation, affecting about 28 percent of Lotronex users. Some had constipation so severe they had to quit taking Lotronex, while others took fiber or laxatives, or temporarily stopped the drug until their constipation was relieved, he said.
Lotronex does pose one serious concern, Raczowski said: Four patients have developed ischemic colitis, a potentially lifethreatening inflammation of the large intestine. All four recovered when they quit taking the drug, and the FDA cannot prove Lotronex caused the problem.
But the FDA is warning patients that if they suffer sudden worsening of abdominal pain or see any blood in their bowel movements, they immediately should stop taking Lotronex and call a doctor.
Doctors must be alert to possible colitis cases and report any to the government at 1-888-INFO-FDA, Raczowski said. Manufacturer Glaxo Wellcome Inc. has promised to clear up just how big this risk by studying several thousand more patients once Lotronex hits the market.
Patients take one tablet twice a day. The prescription-only drug will be on pharmacy shelves by mid-March and will cost $1.98 a tablet, Glaxo said.