medwireNews: The US Food and Drug Administration (FDA) has approved linaclotide for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation (IBS-C) in adults.

The guanylate cyclase type C receptor, licenses for which have also been filed in Europe and the UK, is approved at a dose of 145 µg/day, with a boxed warning that it is unsuitable for patients aged less than 17 years.

Linaclotide was shown to be effective for chronic idiopathic constipation in two 12-week trials published in TheNew England Journal of Medicine in 2011. In all, 1276 patients were treated with linaclotide 145 or 290 µg/day, or placebo.

The primary endpoint of three or more complete spontaneous bowel movements (CSBMs) per week plus an increase of one or more CSBMs during at least 9 of the 12 weeks was achieved by significantly more linaclotide-treated patients than controls. Specifically, 21.2% and 16.0% of patients taking 145 µg/day and 19.4% and 21.3% of those given 290 µg/day achieved these goals, respectively, compared with just 3.3% and 6.0% of controls.

Diarrhea was the only adverse effect reported by significantly more linaclotide-treated patients than controls, affecting 4.2% of both dosing groups.

Results were also reported in Gastroenterology for two linaclotide trials presented at the American Gastroenterology Association in 2011, demonstrating its efficacy in over 800 patients with IBS-C meeting modified Rome II criteria.

Patients given linaclotide 266 µg/day over 12 weeks followed by a 4-week withdrawal period were significantly more likely than placebo-treated patients to achieve the combined endpoint of 30% or greater reduction in pain, three or more CSBMs per week, and an increase of at least one CSBM per week for 9 of the 12 weeks (12.1 vs 5.1%). Linaclotide-treated patients were also significantly more likely than controls to meet three other primary endpoints and 10 secondary endpoints.

A similar reduction in symptoms was also sustained in a second study conducted over 26 weeks; diarrhea was a common side effect in both studies.

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