The North America-based, randomized, multi-center, double-blind, placebo-controlled, dose-range-finding, parallel group phase II(b) study was designed to assess the safety, efficacy, and dose response of linaclotide in patients with IBS-C.
The primary efficacy endpoint was change from baseline in complete spontaneous bowel movement (CSBM) frequency. The study evaluated the effects of 75, 150, 300, or 600 ug linaclotide or placebo administered to adults meeting modified Rome II criteria for IBS-C.
Participants underwent a two-week pretreatment (baseline) period before undergoing the 12-week treatment period, followed by a two-week post-treatment period. Daily assessments of bowel habits and symptom severity, and weekly global assessments were performed using an interactive voice response system. During the baseline period, patients had to demonstrate <3 CSBM/week and mean daily abdominal pain of at least mild severity. Treatment effects in the intent-to-treat population were estimated using an analysis of covariance and the Cochran-Mantel Haenszel test.