Pharmacology · Opioids and antagonists
Remifentanil !
An ultra-short μ opioid for anaesthesia, broken down by blood esterases. Its effect is gone minutes after stopping, independent of liver or kidney.
Updated 2026-11-01
The figure shows fentanyl, from the same 4-anilidopiperidine family, in the μ receptor bound to its Gi protein; remifentanil occupies the same site.
Mechanism of action
Remifentanil is a potent μ agonist of the fentanyl family with an ester bond that non-specific esterases in blood and tissues hydrolyse very quickly to an almost inactive metabolite. So its effect does not accumulate even after hours of infusion, and pain relief and respiratory depression disappear a few minutes after stopping, regardless of liver or kidney function.
- Potently activates the μ receptor
- Strong pain relief during anaesthesia
- Blood esterases hydrolyse it within minutes
- When the infusion stops, the effect is gone in 5 to 10 minutes
Pharmacokinetics
- Metabolism
- Hydrolysis by non-specific esterases in blood and tissues.
- Elimination
- Independent of liver and kidney.
- Half-life
- Very short, about 8 to 20 minutes.
- Onset and duration
- Rapid onset; no residual pain relief 5 to 10 minutes after stopping.
Indications
- Analgesia during induction and maintenance of general anaesthesia
- Continued analgesia in the immediate postoperative period under direct anaesthesia supervision
Adverse effects
Common
- Nausea and vomiting
- Itching
- Hypotension
- Bradycardia
- Shivering
Contraindications
- Epidural or intrathecal administration (it contains glycine)
- Hypersensitivity to remifentanil
Key interactions
- Benzodiazepines, alcohol and other central nervous system depressants
- Add up to profound sedation, respiratory depression, coma and death.
- Inhaled anaesthetics, propofol and other anaesthetics
- Synergistic: they add respiratory depression, hypotension and bradycardia.
What is monitored
- Continuous monitoring of breathing, oxygen saturation, blood pressure and heart rate
- Pain when the infusion stops
Administration and safety
- Given only by staff trained in anaesthesia and airway management, with continuous monitoring and resuscitation equipment.
- It can cause muscle rigidity, above all of the breathing muscles, managed with a neuromuscular blocker.
- Not given through the same line as blood: esterases in blood products inactivate it.
- When the infusion stops, the line is flushed so no drug left in the tubing is later given as a bolus.
- Before stopping it, other analgesia is given if postoperative pain is expected.
Nursing care
- Watch breathing, saturation, blood pressure and heart rate continuously.
- Check that bridging analgesia was given before the infusion stops.
- Flush and label the line at the end.
- Watch for chest-wall rigidity or difficulty ventilating.
Pregnancy and breastfeeding
It crosses the placenta; when used near delivery, the newborn is watched for respiratory depression.
Test yourself
Think of the answer, then tap the question to see it.
Why does remifentanil's effect disappear so fast?
Because non-specific esterases in blood and tissues hydrolyse it within minutes; it does not accumulate even after a long infusion.
Why is it contraindicated epidurally or intrathecally?
Because of the glycine in the formulation.
What must be done before stopping remifentanil if postoperative pain is expected?
Give other analgesia, because within 5 to 10 minutes no pain relief is left.
Why is it not infused through the same line as blood?
Because esterases in blood products can inactivate it.
Related drugs
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: REMIFENTANIL HYDROCHLORIDE injection, powder, lyophilized, for solution (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 23 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.