Irritable bowel syndrome drug gains FDA approval

By Deborah Kotz, Globe Staff

The US Food and Drug Administration gave the thumbs up Thursday for a new drug to treat chronic constipation that doesn’t respond to standard treatments. The drug, Linzess (linaclotide), is also approved to treat irritable bowel syndrome with constipation. More than one in five Americans experience cramping and difficulty passing stool on a chronic basis, according to the National Institutes of Health, and could be eligible for treatment with this new drug.

Linzess, manufactured by Cambridge-based Ironwood Pharmaceuticals, is a once-daily capsule taken on an empty stomach, at least 30 minutes before breakfast. It works increasing the frequency of bowel movements and also helps to ease abdominal cramps associated with IBS.

“No one medication works for all patients suffering from these gastrointestinal disorders,” Dr. Victoria Kusiak, an FDA deputy director in the Center for Drug Evaluation and Research, said in a statement. “With the availability of new therapies, patients and their doctors can select the most appropriate treatment for their condition.”

Fiber supplements and laxatives are usually the first treatments used for constipation. When those don’t work, doctors can prescribe lubiprostone (Amitiza), which works by increasing fluid in the small intestine to help with the passage of stool. It can cause nausea, diarrhea, and abdominal pain, and its full safety risks remain unknown.

The blockbuster drug tegaserod (Zelnorm) was taken off the market five years ago after it was linked to a higher risk of heart attacks, strokes, and severe chest pain.

Four clinical trials involving nearly 2,900 patients with chronic constipation determined that Linzess worked better than a placebo to increase bowel movements; the most common side effect was diarrhea, according to the FDA. But the trials lasted about 12 weeks, so the long-term hazards remain unknown.

It also hasn’t been compared in a head-to-head trial against Amitiza to see which drug works better and is associated with fewer side effects.

Linzess shouldn’t be used in those 16 years of age or younger due to unknown safety risks and a boxed warning stating this will appear on the drug’s label.