Linaclotide !
A small peptide that acts on the gut lining to release chloride and water into the bowel. Used for constipation-predominant irritable bowel syndrome.
Updated 2026-11-01
Mechanism of action
Linaclotide is a short peptide that is barely absorbed. It binds guanylate cyclase C on the luminal surface of the intestinal lining and raises cyclic GMP inside and outside the cells. Cyclic GMP activates the CFTR channel, which secretes chloride-rich fluid into the lumen; water follows, stools soften and transit speeds up.
- Binds guanylate cyclase C on the gut lining
- Cyclic GMP rises inside and outside the cells
- CFTR opens and secretes chloride; water follows
- Softer stool and faster transit
Pharmacokinetics
- Absorption
- Negligible absorption; it acts locally in the gut
- Onset and duration
- The full benefit may take a week or longer
Indications
- Irritable bowel syndrome with constipation in adults Irritable bowel syndrome →
- Chronic idiopathic constipation in adults Constipation and faecal impaction →
- Functional constipation in children 6 years and older Functional constipation in children →
Adverse effects
Common
- Diarrhoea (the most common)
- Abdominal pain
- Bloating and flatulence
- Headache
Contraindications
- Children under 2 years
- Known or suspected mechanical bowel obstruction
Key interactions
- Other systemic medicines
- It is barely absorbed, so few drug interactions are expected
What is monitored
- Stool frequency and diarrhoea
- Signs of dehydration (thirst, dry mouth, sunken eyes, fast heart rate)
- Abdominal pain
Administration and safety
- Taken once a day on an empty stomach, before a meal.
- Capsules are swallowed whole; if swallowing is hard, the contents can be sprinkled on applesauce or mixed in water and taken at once, or given through a feeding tube.
Nursing care
- Rule out bowel obstruction and check the patient's age before starting.
- Teach that diarrhoea is the most common effect and that severe diarrhoea is reported at once.
- Watch for dehydration in older adults and children.
- Explain that symptoms may return about a week after stopping.
Pregnancy and breastfeeding
It is barely absorbed, so fetal exposure is expected to be very low; its use in pregnancy is decided case by case.
Test yourself
Think of the answer, then tap the question to see it.
Which receptor does linaclotide activate?
Guanylate cyclase C on the luminal surface of the intestinal lining.
Which channel finally secretes chloride after linaclotide?
CFTR, activated by the rise in cyclic GMP.
What is the most common adverse effect of linaclotide?
Diarrhoea.
Related drugs
Related conditions
← Back to the class: Laxatives
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Linaclotide: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 62 (McGraw Hill, 2025).
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Representative model, for educational purposes only.