FDA Approves New Drug to Treat Irritable Bowel Syndrome and Constipation

On August 30, 2012, the FDA approved Linzess (linaclotide) for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation (IBS-C) in adults. Constipation is one of the most common gastrointestinal disorders in the United States, most frequently reported in adults aged 65 years and older. IBS-C is also common, reported to affect 15.3 million people in the United States. IBS-C is characterized by abdominal pain with hard or pellet-like stools at least 25% of the time and loose or watery stools less than 25% of the time.

Linaclotide is a minimally absorbed peptide agonist of the guanylate cyclase C receptor. As demonstrated in two sets of clinical trials, Linzess helps relieve constipation by increasing the frequency of bowel movements and may also help relieve abdominal pain. The new drug is a capsule taken once daily on an empty stomach, at least 30 minutes before eating the first meal of the day.

In two double-blind studies involving 1604 patients with IBS-C, patients were randomized to take 290 µg Linzess or placebo for 12 weeks. Compared with those on placebo, Linzess was more effective in reducing abdominal pain and increasing the number of complete spontaneous bowel movements. The results of these trials and a review of linaclotide can be found at www.ncbi.nlm.nih.gov/pmc/articles/PMC3396047.

In two double-blind studies involving 1272 patients with chronic constipation, patients were randomized to receive Linzess at 145-µg or 290-µg doses or placebo for 12 weeks (www.nejm.org/doi/full/10.1056/NEJMoa1010863). Compared with those on placebo, patients taking Linzess experienced more complete spontaneous bowel movements. Linzess is comarketed by Ironwood Pharmaceuticals and Forest Pharmaceuticals.