The FDA has approved linaclotide (Linzess) for the treatment of chronic idiopathic constipation.
The drug is also approved for subtype of irritable bowel syndrome characterized primarily by constipation and abdominal pain.
More than 60 million people experience chronic constipation, and for many, available treatments are inadequate.
"No one medication works for all patients suffering from these gastrointestinal disorders," said Victoria Kusiak, MD, of the FDA's Center for Drug Evaluation and Research.
"With the availability of new therapies, patients and their doctors can select the most appropriate treatment for their condition," she said in a press release.
The efficacy of linaclotide for chronic idiopathic constipation was demonstrated in two double-blind trials, which included 1,272 patients, who were randomized to receive the drug in dosages of 145 mcg or 290 mcg per day, or placebo for 3 months.
The primary endpoint of the trials was having at least three complete, spontaneous bowel movements each week and an increase of at least one additional movement during 75% of treatment weeks.
That endpoint was reached by 21% and 16% of patients in the two trials receiving the lower dose of the drug, and by 19% and 21% of those on the higher dose, compared with 3% and 6% of those given placebo (P<0.01).
The efficacy for the constipation-predominant subtype of irritable bowel syndrome also was shown in two trials that included a total of 1,604 patients.
On a composite endpoint that included reduction in abdominal pain and an increased number of complete, spontaneous bowel movements, one study had response rates of 12% versus 5% for linaclotide and placebo, respectively (P=0.0004), while responses were 13% versus 3% for the active treatment and placebo groups in the second study (P≤0.0001).
The most common adverse effect reported in the trials was diarrhea.
Because the higher dose was not significantly superior to the lower dose, FDA approval was granted for the 145 mcg dose.
Linaclotide is given once daily, 30 minutes before breakfast.
The drug's labeling will included a boxed warning advising against using the drug in patients 17 years and younger.