The Food and Drug Administration on Thursday approved a new drug, Linzess, to treat irritable bowel syndrome with constipation. The drug, known generically as linaclotide, speeds up bowel movements and reduces pain in many patients with the disorder. It is the second product on the market aimed at the population, following Amitiza (lubiprostone), which was approved in January 2006 but may have more side effects than Linzess.
An estimated 15.3 million Americans suffer from irritable bowel syndrome with constipation, according to the National Institutes of Health, and about 63 million suffer from constipation. Irritable bowel syndrome, or IBS, is characterized by abdominal pain and hard, lumpy stools at least 25% of the time. The cause of the disorder is not clear. Linaclotide is a peptide, composed of 14 amino acids, that binds to an enzyme called guanylate cyclase 2C and stimulates muscle contractions that cause the intestines to move digested food toward excretion.
In one clinical trial, 1,604 patients with IBS were randomly assigned to take either Linzess or a placebo for 12 weeks. The results showed that the drug reduced abdominal pain and increased the number of spontaneous bowel movements. In a separate trial, 1,272 patients with constipation of unknown cause were also assigned to take Linzess or a placebo for 12 weeks. Again, those taking the drug had more spontaneous bowel movements.
The drug’s main side effect is diarrhea, but very few of those taking the drug had severe diarrhea, according to the studies.
Unlike Amitiza, which is taken twice a day, Linzess is taken once a day in the morning, 30 minutes before eating. The drug has not been tested in subjects younger than 17 and has not been approved for use by patients in that age group. The manufacturer said the drug will probably be available for sale in the fourth quarter of this year.