Linaclotide (Linzess)
Overview
A synthetic 14-amino acid peptide structurally related to the heat-stable enterotoxin of Escherichia coli and the endogenous peptide guanylin. Linaclotide activates guanylate cyclase-C (GC-C) on the luminal surface of intestinal epithelium, increasing intracellular cGMP to stimulate CFTR-mediated chloride and bicarbonate secretion, accelerating intestinal transit. Extracellular cGMP also reduces firing of visceral afferent pain fibers, providing analgesic effects in the gut.
Key Research Findings
FDA-approved in 2012 for IBS-C and CIC. Phase 3 trials demonstrated significant improvements in bowel frequency, straining, abdominal pain, and bloating. Minimal systemic absorption (<0.1% bioavailability) provides a favorable safety profile. Shown to reduce abdominal pain independent of its effects on bowel function, supporting a direct visceral analgesic mechanism (Rao et al., NEJM, 2016).
Oral
FDA Approved
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