Constipation drug may bring US patients relief

By Lynda Williams, Senior medwireNews Reporter

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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