Objectives: Chronic constipation is a common gastrointestinal disorder with limited treatment options. Oral administration of linaclotide, a novel peptide agonist of guanylate cyclase-C receptors, has been shown in animal studies to stimulate intestinal fluid secretion and transit. In Phase 1 studies in healthy human volunteers, linaclotide was well-tolerated, increased bowel movement frequency, and loosened stool consistency.
Methods: This randomized, double-blind, placebo-controlled pilot study evaluated the safety, tolerability, and exploratory efficacy of oral linaclotide in 42 patients with chronic constipation. Patients were randomized to linaclotide (100, 300, or 1,000 microg) or placebo once daily for 2 weeks. Bowel habits (stool frequency, consistency, straining, completeness of evacuation) and degree of abdominal discomfort were monitored daily using an interactive voice response system. Patient-reported outcomes of severity of constipation and overall relief were evaluated weekly.
Results: Linaclotide treatment produced dose-dependent increases from the pretreatment baseline values in weekly complete spontaneous bowel movement frequency (range: 2.2-3.2), stool consistency scores (range: 1.1-2.6, 7-point scale), and straining scores (range: 0.4-1.5, 7-point scale); corresponding placebo increases were 1.3, 0.4, 0.4, respectively. Clinical improvements were also demonstrated in abdominal discomfort, severity of constipation, and overall relief. Compared to placebo, linaclotide 100 microg/day significantly increased spontaneous bowel movement frequency, and linaclotide 1,000 microg/day significantly improved stool consistency (P<0.05). Adverse events were primarily gastrointestinal, with diarrhea being the most common.
Conclusions: In this pilot study, linaclotide treatment improved bowel habits and symptoms of patients with chronic constipation. Further randomized controlled trials are warranted.