Linaclotide
approvedAlso known as: Linzess, Constella
**Mechanism of Action** Linaclotide is a 14-amino acid synthetic peptide that acts as a potent agonist of guanylate cyclase-C (GC-C), a receptor expressed on the luminal surface of intestinal epithelial cells. Binding to GC-C increases intracellular cyclic guanosine monophosphate (cGMP) levels, which activates the cystic fibrosis transmembrane conductance regulator (CFTR) and promotes chloride and bicarbonate secretion into the intestinal lumen. This ionic flux drives water secretion, accelerating gastrointestinal transit and softening stool. Additionally, elevated extracellular cGMP may reduce visceral hypersensitivity by modulating nociceptive signaling, contributing to its analgesic effects in irritable bowel syndrome with constipation (IBS-C). **Key Research Findings** Clinical trials demonstrate linaclotide significantly improves spontaneous bowel movement frequency, stool consistency, and abdominal pain in IBS-C and chronic idiopathic constipation (CIC) patients. A pivotal Phase III trial (NCT00948818) showed 33.7% of IBS-C patients achieved the FDA composite endpoint (≥30% reduction in abdominal pain and ≥1 spontaneous bowel movement/week increase) vs. 13.8% with placebo. Long-term safety data indicate minimal systemic absorption (<0.1%) and low adverse event rates, primarily diarrhea (20% vs. 3% placebo). Mechanistic studies confirm GC-C activation is essential for its pro-secretory and anti-nociceptive effects, with no evidence of tolerance or dependence. **Clinical Relevance** Approved by the FDA (2012) and EMA (2013) for IBS-C and CIC, linaclotide is a first-line therapy for patients unresponsive to lifestyle modifications or laxatives. Its dual action on constipation and abdominal pain distinguishes it from traditional osmotic or stimulant laxatives. Contraindicated in pediatric patients <6 years and those with mechanical gastrointestinal obstruction. Diarrhea is the most common adverse effect, requiring dose adjustment or discontinuation in ~5% of patients. For research purposes only — not medical advice.
Key data
C59H79N15O21S6Research & studies
Functional bloating and abdominal distension are common and often overlap with other gut-brain interaction disorders.; Diagnosis is based on Rome IV criteria after excluding organic disease, with no need for lab or imaging tests if no alarming signs.; Pathophysiology involves visceral hypersensitivity, abdomino-phrenic dyssynergia, intestinal dysmotility, and dysbiosis.; Treatment includes dietary changes, probiotics, antispasmodics, rifaximin, secretagogues, neuromodulators, and cognitive behavioral therapy.
First-line treatment involves lifestyle modification and dietary therapy before specialized testing or symptom-based classification.; Medical therapy options include osmotic laxatives, secretagogues, bile acid transporter inhibitors, probiotics, prokinetics, and Kampo medicines.; Linaclotide is a small peptide agonist of guanylate cyclase C receptors, minimally absorbed, and not linked to serum enzyme elevations or liver injury.; Linaclotide is acceptable in nursing mothers with no special precautions required.
Linaclotide increased SBM frequency by 2.22 per week vs 1.05 with placebo (difference 1.17, p<0.0001).; Stool consistency improved significantly with linaclotide (difference 0.42, p=0.0001).; Diarrhoea occurred in 4% of linaclotide patients vs 2% with placebo; one serious diarrhoea case required hospitalization.; No deaths occurred; linaclotide was well tolerated overall.
Constipation symptoms include infrequent bowel movements, hard stools, and straining.; Bristol Stool Form Scale, colonoscopy, and digital rectal exam aid diagnosis.; Physiological tests are recommended for treatment-resistant cases or suspected defecatory disorders.; Meta-analysis supports benefits and cautions for lubiprostone, linaclotide, and conventional laxatives.
IBS is characterized by abdominal pain, bloating, distention, and altered bowel habits without structural or biochemical abnormalities.; The condition affects 5%-10% of healthy individuals at any given time and typically follows a relapsing-remitting course.; Its aetiopathogenesis and pathophysiological mechanisms remain unknown.; Management includes dietary, pharmacological, and psychotherapeutic approaches.
IBS affects about 20% of the population, mainly women, and has four subtypes: IBS-C, IBS-D, mixed, and unclassified.; Management requires a strong physician-patient relationship, patient education, dietary advice, and stress reduction.; For IBS-D, options include antibiotics like rifaximin, peripheral opioid agonists, and serotonin antagonists; for IBS-C, first-line therapy includes bulking agents and osmotic laxatives.; Linaclotide is minimally absorbed and appears acceptable for nursing mothers without special precautions.
Frequently asked questions
What is Linaclotide?
**Mechanism of Action** Linaclotide is a 14-amino acid synthetic peptide that acts as a potent agonist of guanylate cyclase-C (GC-C), a receptor expressed on the luminal surface of intestinal epithelial cells. Binding to GC-C increases intracellular cyclic guanosine monophosphate (cGMP) levels, which activates the cyst
How does Linaclotide work?
Guanylate cyclase-C agonist 14-aa peptide that increases intestinal fluid secretion and transit; approved for IBS-C and chronic constipation.
What is the research status of Linaclotide?
Linaclotide is currently classified as approved, with 465 research references on record. This is for research purposes only and is not medical advice.
What is the molecular weight of Linaclotide?
Linaclotide has a molecular weight of approximately 1526.8 g/mol (formula C59H79N15O21S6).
Related peptides
GLP-2 receptor agonist that promotes intestinal mucosal growth and absorption; approved for short bowel syndrome.
Uroguanylin-analog GC-C agonist that promotes pH-dependent intestinal fluid secretion; approved for chronic idiopathic constipation and IBS-C.
Tight-junction-regulating octapeptide that reduces intestinal permeability ('leaky gut'); trialed as an adjunct for celiac disease.
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