Linzess (Linaclotide)
linaclotide
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Irritable bowel syndrome with constipation (IBS-C) | Adults and pediatric patients ≥7 years | Monotherapy | FDA Approved |
| Chronic idiopathic constipation (CIC) | Adults | Monotherapy | FDA Approved |
| Functional constipation (FC) | Pediatric patients ≥6 years | Monotherapy | FDA Approved |
Linaclotide is a 14-amino-acid peptide that acts locally in the gut to treat constipation-predominant conditions. It received initial FDA approval in 2012 for adults with IBS-C and CIC. The pediatric IBS-C indication for patients 7 years and older and the functional constipation indication for patients 6 years and older were added subsequently, with the most recent label revision in November 2025. The AGA issued a strong recommendation for linaclotide in IBS-C based on high-certainty evidence (AGA 2022), and both the AGA and ACG jointly recommended linaclotide strongly for CIC in adults who do not respond to over-the-counter agents (AGA/ACG 2023).
Opioid-induced constipation (OIC): Some clinicians trial linaclotide when PAMORAs are insufficient, though evidence is limited to case series. Evidence quality: Low.
Constipation associated with systemic sclerosis: Small observational studies suggest benefit for refractory lower GI dysmotility in scleroderma. Evidence quality: Very low.
Dosing
Adult Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| IBS-C — adult | 290 mcg once daily | 290 mcg once daily | 290 mcg/day | No titration required; take on empty stomach ≥30 min before first meal Higher dose reflects visceral pain component in IBS-C |
| CIC — standard therapy | 145 mcg once daily | 145 mcg once daily | 145 mcg/day | Recommended dose for CIC; take on empty stomach 290 mcg did not consistently add clinical benefit over 145 mcg in CIC trials |
| CIC — tolerability-guided low-dose start | 72 mcg once daily | 72–145 mcg once daily | 145 mcg/day | Consider for patients at higher diarrhea risk or with milder symptoms May step up to 145 mcg if inadequate response |
Pediatric Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| IBS-C — pediatric ≥7 years | 145 mcg once daily | 145 mcg once daily | 145 mcg/day | Higher doses did not show additional benefit in pediatric IBS-C trial Approved November 2025 |
| Functional constipation — pediatric ≥6 years | 72 mcg once daily | 72 mcg once daily | 72 mcg/day | Only the 72 mcg dose is approved for pediatric FC Capsules may be opened and mixed with applesauce or water |
Linaclotide must be taken on an empty stomach at least 30 minutes before the first meal of the day. Taking it after a high-fat breakfast increases stool frequency and looseness. For patients who cannot swallow capsules, the contents can be sprinkled on applesauce, dispersed in water, or administered via nasogastric or gastrostomy tube. The drug is coated on the bead surface and dissolves into the water — it is not necessary to consume every bead to receive the complete dose.
Pharmacology
Mechanism of Action
Linaclotide is a synthetic 14-amino-acid peptide structurally related to the endogenous hormones guanylin and uroguanylin. It binds to and activates guanylate cyclase-C (GC-C) receptors on the luminal surface of the intestinal epithelium. This activation increases both intracellular and extracellular concentrations of cyclic guanosine monophosphate (cGMP). Intracellular cGMP stimulates chloride and bicarbonate secretion through the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel, resulting in increased intestinal fluid secretion and accelerated gastrointestinal transit. Extracellular cGMP decreases the firing of visceral pain-sensing afferent neurons, which is believed to mediate the analgesic effect observed in IBS-C patients — an effect not shared by all secretagogues. Both linaclotide and its active des-tyrosine metabolite contribute to this dual mechanism of secretion and pain reduction.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Negligible systemic absorption; plasma concentrations below limit of quantitation at all approved doses (72, 145, 290 mcg) | Standard PK parameters (AUC, Cmax, t½) cannot be calculated; acts locally in the GI lumen |
| Distribution | Not distributed systemically to any clinically relevant extent | No dose adjustment needed for organ impairment; minimal off-target systemic effects expected |
| Metabolism | Metabolized in GI tract by loss of terminal tyrosine to form active des-tyrosine metabolite; both are then proteolytically degraded to smaller peptides and amino acids | No CYP enzyme involvement; no interaction with P-glycoprotein or common transporters |
| Elimination | Fecal recovery of active metabolite ~5% (fasted), ~3% (fed) after 290 mcg daily for 7 days | Majority degraded within intestinal lumen; renal and hepatic clearance not relevant |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Diarrhea | 20% (IBS-C 290 mcg); 16% (CIC 145 mcg); 19% (CIC 72 mcg) | Dose-dependent; majority begins within first 2 weeks; 90.5% of cases are mild-to-moderate in pooled Phase 3 data; severe diarrhea in ~2% at 145/290 mcg, <1% at 72 mcg |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Abdominal pain | 7% (IBS-C); 7% (CIC) | Includes upper, lower, and generalized abdominal pain; usually self-limiting |
| Flatulence | 4% (IBS-C); 6% (CIC) | Related to increased fluid secretion in the lumen; tends to improve over time |
| Abdominal distension | 2% (IBS-C); 3% (CIC) | More noticeable in early treatment; may paradoxically improve with continued use as bowel function normalizes |
| Headache | 4% (IBS-C) | Not consistently higher than placebo in CIC trials |
| Upper respiratory tract infection | 5% (CIC) | Likely coincidental; noted in CIC trials (placebo 4%) |
| Sinusitis | 3% (CIC) | Reported in CIC trials (placebo 2%) |
| Viral gastroenteritis | 3% (IBS-C) | Placebo rate was 1% in IBS-C trials |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Severe diarrhea with dehydration, hypotension, syncope | ~2% (severe diarrhea); dehydration rare | First 2 weeks | Suspend dosing immediately; rehydrate; check electrolytes (hypokalemia, hyponatremia reported); hospitalization or IV fluids may be required |
| Anaphylaxis | Very rare (postmarketing) | Any time | Emergency care; permanent discontinuation; do not rechallenge |
| Angioedema | Very rare (postmarketing) | Any time | Discontinue; assess airway; standard angioedema management |
| Hematochezia / rectal hemorrhage | Rare (postmarketing) | Variable | Evaluate for alternative GI pathology; discontinue if clinically warranted |
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Diarrhea | 5% (IBS-C); 2–5% (CIC) | Placebo <1% in both populations; the 72 mcg CIC dose has 2% discontinuation rate |
| Abdominal pain | 1% (both IBS-C and CIC) | Placebo <1% in both populations |
| Dose reduction/suspension (open-label long-term) | 27–29% | In long-term safety studies up to 18 months with 290 mcg; majority due to GI adverse reactions |
Diarrhea is the most clinically important adverse effect. Counsel patients that it typically begins within the first two weeks and is usually self-limiting. For patients experiencing bothersome loose stools on 145 mcg, a step-down to 72 mcg (in the CIC indication) may improve tolerability. If severe diarrhea occurs — particularly if accompanied by dizziness, faintness, or bloody stools — suspend the dose and ensure adequate oral or intravenous rehydration. Monitor electrolytes in patients presenting with dehydration symptoms.
Drug Interactions
Linaclotide has a uniquely favorable drug interaction profile. Because it acts locally in the intestinal lumen with negligible systemic absorption, it does not interact with the cytochrome P450 enzyme system, nor with common efflux or uptake transporters including P-glycoprotein. No formal drug-drug interaction studies have been conducted because systemic exposures are below measurable thresholds. This means that linaclotide can be co-prescribed with virtually any medication without pharmacokinetic concerns. However, a few pharmacodynamic considerations remain relevant.
The absence of CYP, transporter, or systemic pharmacokinetic interactions makes linaclotide suitable for patients on complex medication regimens — a particularly valuable feature in elderly patients with multiple comorbidities. No dose adjustment is needed for concomitant medications.
Monitoring
-
Stool Pattern
Weeks 1–2, then monthly
Routine Assess stool frequency, consistency (Bristol Stool Form Scale), and presence of diarrhea. Most diarrhea begins within the first 2 weeks. If severe, suspend dosing and consider step-down to 72 mcg (CIC) or discontinuation. -
Hydration Status
First 2 weeks, then as needed
Routine Monitor for signs of dehydration (orthostatic symptoms, reduced urine output, dry mucous membranes), particularly in elderly patients and those on diuretics. Parenteral rehydration may be necessary in severe cases. -
Electrolytes
If severe diarrhea occurs
Trigger-based Hypokalemia and hyponatremia have been reported in postmarketing surveillance in patients experiencing severe diarrhea. Check basic metabolic panel if diarrhea is persistent or severe. -
Abdominal Symptoms
Baseline, then at follow-up visits
Routine Track abdominal pain severity and bloating response. In IBS-C, improvement should be evident by weeks 6–9. Reassess treatment if no benefit after 4–6 weeks at the recommended dose. -
GI Bleeding
If bloody stools reported
Trigger-based Hematochezia and rectal hemorrhage have been reported postmarketing. Any new-onset bloody stools should prompt investigation for alternative pathology and consideration of drug discontinuation. -
Treatment Efficacy
4–8 weeks after initiation
Routine Evaluate whether the patient has met treatment goals for bowel frequency (target ≥3 CSBMs/week) and symptom improvement. If inadequate, consider dose adjustment (for CIC) or alternative agent.
Contraindications & Cautions
Absolute Contraindications
- Age <2 years: Contraindicated due to risk of fatal dehydration from GC-C agonism-induced fluid secretion in neonatal intestine (FDA Boxed Warning).
- Known or suspected mechanical gastrointestinal obstruction: Secretory effects may worsen obstruction-related complications.
Relative Contraindications (Specialist Input Recommended)
- Age 2 to <6 years (for FC) or 2 to <7 years (for IBS-C): Safety and efficacy not established in these age groups; risk-benefit discussion required if considering off-label use.
- Known hypersensitivity to linaclotide or any excipient: Anaphylaxis and angioedema have been reported postmarketing.
Use with Caution
- Elderly patients on diuretics or with limited fluid intake: Higher susceptibility to dehydration from drug-induced diarrhea.
- Patients with inflammatory bowel disease: Not studied in IBD; theoretical concern that increased secretion could exacerbate diarrhea in active disease.
- Pregnancy: No adequate human data, though negligible systemic absorption suggests low fetal risk. Use only if benefit justifies potential risk.
Linaclotide is contraindicated in patients less than 2 years of age. In nonclinical studies, administration of a single clinically relevant adult oral dose of linaclotide to neonatal mice (human age equivalent approximately 0 to 28 days) caused deaths due to rapid and severe dehydration from elevated GC-C agonism in the immature intestine. Insufficient data on GC-C expression in children under 2 years prevents adequate risk assessment in this age group. Accidental ingestion by young children can be life-threatening — patients must be counseled to store the medication securely out of reach of children.
Patient Counselling
Purpose of Therapy
Linaclotide works directly in the intestine to increase fluid secretion, soften stools, speed up bowel transit, and — in IBS-C — reduce abdominal pain. It is not a laxative in the traditional sense and takes a different approach to relieving constipation. Most patients start to notice improvement in bowel frequency within the first week, but the full effect on abdominal pain may take several weeks to develop.
How to Take
Take one capsule every day on an empty stomach, at least 30 minutes before your first meal of the day, at about the same time each day. Do not crush or chew the capsule. If you cannot swallow capsules, the capsule can be opened and the beads sprinkled on a teaspoon of applesauce (swallow immediately without chewing) or mixed with 30 mL of room-temperature bottled water. If you miss a dose, skip it and take the next one at your regular time — never double up.
Sources
- LINZESS (linaclotide) capsules, for oral use. Full Prescribing Information. AbbVie Inc. and Ironwood Pharmaceuticals, Inc. Revised November 2025. FDA label Primary source for all dosing, adverse reaction rates, contraindications, and pharmacokinetic data in this monograph.
- Linzess (linaclotide) FDA Approval History. Drugs.com. Accessed April 2026. Drugs.com Comprehensive timeline of FDA regulatory actions from initial 2012 approval through pediatric indications.
- Rao S, Lembo AJ, Shiff SJ, et al. A 12-week, randomized, controlled trial with a 4-week randomized withdrawal period to evaluate the efficacy and safety of linaclotide in irritable bowel syndrome with constipation. Am J Gastroenterol. 2012;107(11):1714–1724. DOI Pivotal Phase 3 IBS-C trial (Trial 1) establishing efficacy of 290 mcg on CSBM frequency and abdominal pain.
- Chey WD, Lembo AJ, Lavins BJ, et al. Linaclotide for irritable bowel syndrome with constipation: a 26-week, randomized, double-blind, placebo-controlled trial to evaluate efficacy and safety. Am J Gastroenterol. 2012;107(11):1702–1712. DOI Pivotal Phase 3 IBS-C trial (Trial 2) demonstrating sustained efficacy and safety over 26 weeks.
- Lembo AJ, Schneier HA, Shiff SJ, et al. Two randomized trials of linaclotide for chronic constipation. N Engl J Med. 2011;365(6):527–536. DOI Two pivotal CIC trials (Trials 3 and 4) establishing efficacy of 145 mcg and 290 mcg for chronic constipation.
- Chang L, Lacy BE, Moshiree B, et al. Efficacy of linaclotide in reducing abdominal symptoms of bloating, discomfort, and pain: a phase 3b trial using a novel abdominal scoring system. Am J Gastroenterol. 2021;116(9):1929–1937. DOI Phase 3b trial (Trial 6) demonstrating improvement in composite abdominal symptom score in IBS-C.
- Chang L, Sultan S, Lembo A, et al. AGA Clinical Practice Guideline on the pharmacological management of irritable bowel syndrome with constipation. Gastroenterology. 2022;163(1):118–136. DOI Strong recommendation for linaclotide in IBS-C based on high-certainty evidence (highest among all IBS-C pharmacotherapies).
- Chang L, Chey WD, Imdad A, et al. American Gastroenterological Association–American College of Gastroenterology Clinical Practice Guideline: pharmacological management of chronic idiopathic constipation. Gastroenterology. 2023;164(7):1086–1106. DOI Joint AGA/ACG guideline strongly recommending linaclotide for CIC after failure of over-the-counter agents.
- Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: management of irritable bowel syndrome. Am J Gastroenterol. 2021;116(1):17–44. DOI ACG guideline recommending GC-C agonists for IBS-C based on high-quality evidence.
- Busby RW, Bryant AP, Bartolini WP, et al. Linaclotide, through activation of guanylate cyclase C, acts locally in the gastrointestinal tract to elicit enhanced intestinal secretion and transit. Eur J Pharmacol. 2010;649(1–3):328–335. DOI Preclinical study characterizing the local GI mechanism of action including secretion, transit acceleration, and visceral analgesia.
- Castro J, Harrington AM, Hughes PA, et al. Linaclotide inhibits colonic nociceptors and relieves abdominal pain via guanylate cyclase-C and extracellular cyclic guanosine 3′,5′-monophosphate. Gastroenterology. 2013;145(6):1334–1346.e11. DOI Mechanistic study demonstrating the extracellular cGMP-mediated inhibition of visceral pain signaling.
- Nee JW, Engel SS, Engel AE, et al. Safety and tolerability of linaclotide for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation: pooled Phase 3 analysis. Expert Rev Gastroenterol Hepatol. 2019;13(4):397–406. DOI Comprehensive pooled safety analysis across all six Phase 3 RCTs and two long-term safety studies (up to 78 weeks, N=3853).
- Linaclotide. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024. Updated February 29, 2024. NCBI Bookshelf Clinician-oriented review of linaclotide pharmacology, dosing, and clinical use across indications including off-label applications.