Alvimopan
Laxatives
Laxatives
A gut-only opioid blocker used in hospital after bowel resection to speed the return of bowel function, for a short course only.
Quick facts
- Group
- Laxatives
- Target
- Mu-opioid receptor in the gut (peripheral antagonist)
- Used for
- Faster recovery of upper
- Key effects
- Dyspepsia · Low potassium
- Monitor
- Return of bowel sounds · Total number of doses given
- ATC
- A06AH02
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows alvimopan bound to the inactive mouse mu-opioid receptor, which closely resembles the human receptor.
Alvimopan is a selective mu-opioid receptor antagonist with no agonist activity. Taken by mouth, little is absorbed, so it blocks opioid receptors in the gut wall while opioid pain relief, which is mainly central, is kept. This shortens postoperative ileus after bowel resection. A gut-flora metabolite is also a mu antagonist.
- Opioids and surgery slow the gut via mu receptors
- Alvimopan blocks gut mu receptors, barely absorbed
- Bowel function returns sooner; analgesia is kept
Indications
- Faster recovery of upper and lower gut function after surgery with partial bowel resection and primary anastomosis (hospital use) Postoperative ileus →
Adverse effects
Common
- Dyspepsia
- Low potassium, anaemia, back pain, urinary retention
Contraindications
- Therapeutic opioid use for more than seven consecutive days before starting
- Not recommended: severe hepatic impairment, end-stage renal disease, complete bowel obstruction, pancreatic or gastric anastomosis
Key interactions
- Recent or ongoing opioid therapy
- Patients are more sensitive to its GI effects; long prior use is a contraindication
- IV morphine
- No clinically important change in morphine levels
What is monitored
- Return of bowel sounds, flatus and stool
- Chest pain or cardiac symptoms
- Total number of doses given
Administration and safety
- Hospital use only, through a restricted program; a short course with a fixed maximum number of doses.
- The first dose is given before surgery, then continued after surgery until discharge or the course ends.
- Not sent home with the patient.
Pregnancy and breastfeeding
Human data are limited and insufficient to define a risk; animal studies showed no fetal harm.
Nursing care
- Before the first dose, confirm the patient has not taken opioids for more than a week.
- Count doses so the maximum is not exceeded.
- Monitor bowel sounds, flatus, stool and tolerance of diet.
- Report chest pain promptly.
Pharmacokinetics
- Absorption
- Low oral bioavailability; peak in plasma within a few hours; fatty food lowers absorption
- Metabolism
- Gut bacteria convert it to an active metabolite that appears later and accumulates
Test yourself
Think of the answer, then tap the question to see it.
Why does alvimopan not reverse opioid analgesia?
Little is absorbed, so it blocks mu receptors in the gut but not in the brain.
Which history is a contraindication?
Therapeutic opioid use for more than seven consecutive days before starting.
Why is use short-term and in hospital only?
A long-term trial showed more myocardial infarctions.
Connections
← 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: DailyMed - ALVIMOPAN capsule (DailyMed (U.S. National Library of Medicine), 2022); Alvimopan: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); RCSB PDB - 7UL4: CryoEM Structure of Inactive MOR Bound to Alvimopan and Mb6 (RCSB Protein Data Bank, 2026).
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Representative model, for educational purposes only.