Methodone
๐ก Always confirm the patientโs methadone dose with their usual dispensing pharmacy.
Self-reported doses are often inaccurate, and errors carry high risk of overdose or withdrawal.
๐ About
- Check the BNF entry or local guidelines for up-to-date advice.
- Methadone is a synthetic opioid, mainly used in opioid substitution therapy (OST) and occasionally in chronic pain or palliative care.
- It has a long half-life (15โ60 h), leading to accumulation risk and variable patient response.
โ๏ธ Mode of Action
- Full ฮผ-opioid receptor agonist โ analgesia, euphoria, respiratory depression.
- Also NMDA receptor antagonist โ may help with neuropathic pain.
- Long duration of action makes it suitable for opioid dependence maintenance therapy.
๐ Indications & Example Doses
| Indication | Typical Starting Dose | Frequency | Route |
|---|
| Opioid dependence (substitution therapy) | 10โ30 mg daily, titrated carefully | OD | PO |
| Chronic pain (specialist use) | 2.5โ10 mg | 8โ12 hourly | PO |
| Cough palliation (palliative) | 1โ2 mg | 6 hourly | PO |
โ ๏ธ Dosing must always be individualised, especially in dependence therapy. ECG monitoring is advised at higher doses due to QT risk.
๐ Interactions
- QT prolongation: risk increased with macrolides, fluoroquinolones, amiodarone, antipsychotics.
- Avoid with MAOIs (within 2 weeks).
- CYP3A4 inhibitors (e.g. azole antifungals, clarithromycin) โ methadone levels.
- CYP inducers (e.g. carbamazepine, phenytoin, rifampicin) โ methadone levels โ withdrawal risk.
โ ๏ธ Cautions
- Concurrent sedatives (benzodiazepines, alcohol) โ risk of fatal respiratory depression.
- Use with caution in hepatic/renal impairment.
- Long QT syndrome or electrolyte abnormalities (hypokalaemia, hypomagnesaemia).
- Elderly, frail, or opioid-naรฏve patients โ extreme caution.
๐ซ Contraindications
- Severe respiratory depression.
- Paralytic ileus.
- Acute asthma, head injury or raised ICP.
- Comatose patients, phaeochromocytoma.
๐ฅ Side Effects
- Common: nausea, vomiting, constipation, sweating, dry mouth, sedation.
- Serious: respiratory depression, cardiac arrhythmias (QT prolongation, torsades de pointes), dependence, overdose risk.
๐ References
๐ Revisions
- Expanded with safety pearls and interaction risks โ August 2025
