[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Opioids and antagonists](https://durgical.com/en/pharmacology/classes/opioids-and-antagonists/) › Pethidine

[Pharmacology](https://durgical.com/en/pharmacology/) · [Opioids and antagonists](https://durgical.com/en/pharmacology/classes/opioids-and-antagonists/)

# Pethidine

A short-acting synthetic opioid. Its metabolite norpethidine builds up and causes tremor and seizures; with MAOIs it is dangerous.

Updated 2026-11-01

- Class: [Opioids and antagonists](https://durgical.com/en/pharmacology/classes/opioids-and-antagonists/)
- Receptor: μ-opioid receptor
- ATC code: N02AB02

## ⚠ High-alert medication

An error with this medicine can cause serious harm: double checks and protocols are used.

Also called: meperidine

◎**μ-opioid receptor**Pethidine

ⓘ The figure shows morphine in the μ receptor; pethidine, a phenylpiperidine, occupies the same site. There is no structure of pethidine in the receptor.

**Target in 3D:** μ-opioid receptor. PDB structure 8EF6 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8EF6) · Drag to rotate · pinch to zoom

## Mechanism of action

Pethidine is a synthetic μ agonist of the phenylpiperidine family. It relieves pain like other μ agonists and also has local anaesthetic properties. In the liver it is N-demethylated to norpethidine, a metabolite with a much longer half-life that stimulates the nervous system; with repeated doses or kidney disease it builds up and causes excitation, tremor, myoclonus and seizures.

- Activates the μ receptor in the pain pathway
- Short-lived pain relief
- The liver turns it into norpethidine, with a long half-life
- Built-up norpethidine excites the nervous system: seizures

## Pharmacokinetics

**Metabolism**
Liver: N-demethylation to norpethidine and hydrolysis; in cirrhosis its bioavailability rises and its half-life lengthens.

**Elimination**
Kidney; norpethidine accumulates in renal failure.

**Half-life**
About 3 hours for pethidine and about 15 to 20 hours for norpethidine.

## Indications

- Acute pain needing an opioid, for a limited time
- Obstetric analgesia and as a supplement to anaesthesia
- Post-anaesthetic shivering

## Adverse effects

### Common

- Lightheadedness, dizziness and sedation
- Nausea and vomiting
- Sweating

### Serious (rare, important)

- Life-threatening respiratory depression, above all at the start or after a dose increase
- Addiction, abuse and misuse, with risk of overdose and death
- Neonatal opioid withdrawal syndrome with prolonged use in pregnancy
- Adrenal insufficiency with prolonged use
- Severe hypotension
- Tremor, myoclonus and seizures from norpethidine build-up
- Serotonin syndrome with MAOIs or other serotonergic drugs

## Contraindications

- Significant respiratory depression
- Acute or severe bronchial asthma without monitoring or resuscitation equipment
- Known or suspected gastrointestinal obstruction, including paralytic ileus
- Hypersensitivity to the drug
- Current use of monoamine oxidase inhibitors or use within the last 14 days

## Key interactions

**Monoamine oxidase inhibitors**
Contraindicated: severe reactions with excitation, hyperthermia, rigidity and serotonin syndrome, or profound depression.

**SSRIs, SNRIs and other serotonergic drugs**
Risk of serotonin syndrome.

**Benzodiazepines, alcohol and other central nervous system depressants**
Add up to profound sedation, respiratory depression, coma and death.

## What is monitored

- Respiratory rate and sedation
- Tremor, myoclonus or agitation
- Kidney function
- Total duration of treatment

## Administration and safety

- Prolonged use raises the risk of norpethidine toxicity; it is not considered an opioid for chronic pain.
- In older adults and in kidney disease it is used with great caution because norpethidine accumulates.
- Intravenous doses are given slowly.
- Controlled medicine: the order is verified, every dose recorded and leftovers kept secure.

## Nursing care

- Before each dose: respiratory rate, oxygen saturation and sedation level; hold the dose and report excessive sedation or slow breathing.
- Keep naloxone at hand and teach the family to recognise an overdose.
- Watch for tremor, muscle jerks, agitation or seizures, above all after several doses.
- Check for use of MAOIs and serotonergic antidepressants.

## Pregnancy and breastfeeding

Prolonged use in pregnancy can cause neonatal opioid withdrawal syndrome, which is expected and treatable; the newborn is watched after birth.

## Memory aid

PETHIDINE and its daughter NORpethidine: the mother soothes briefly, the daughter stays 15 to 20 hours and makes the nervous system seize. With MAOIs, never.

## Test yourself

Think of the answer, then tap the question to see it.

## Why is pethidine not used for chronic pain or in renal failure?

Because its metabolite norpethidine, long-lived and renally cleared, builds up and causes tremor, myoclonus and seizures.

## What serious interaction does pethidine have with MAOIs?

It can cause serotonin syndrome with excitation, hyperthermia and rigidity, or profound depression; the combination is contraindicated.

## Which specific anaesthetic use is pethidine remembered for?

Treating post-anaesthetic shivering.

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## Related drugs

- [Morphine](https://durgical.com/en/pharmacology/morphine/)
- [Fentanyl](https://durgical.com/en/pharmacology/fentanyl/)
- [Tramadol](https://durgical.com/en/pharmacology/tramadol/)

[← Back to the class: Opioids and antagonists](https://durgical.com/en/pharmacology/classes/opioids-and-antagonists/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Meperidine: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682117.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [MEPERIDINE HYDROCHLORIDE injection](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e0e998da-f056-4fce-be8e-ed60cf3b461b) (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](https://atcddd.fhi.no/atc_ddd_index/?code=N02AB02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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