Naloxone
Class: opioid antagonist
Indications: opioid overdose – reverses opioid effects
Unlicensed indications: may enhance opioid analgesia at very low dose, may attenuate opioid adverse effects e.g. nausea and vomiting at low dose
Contraindications/cautions: cardiovascular disease
Adverse reactions: common: nausea, vomiting, tachycardia, sweating, raised blood pressure (opioid withdrawal), headache, dizziness; less common: diarrhoea, dry mouth
Metabolism/clearance: metabolised mainly in the liver by glucuronidation
Interactions:
- blocks the actions of opioids e.g. morphine, fentanyl, methadone, oxycodone
| Dosing: | If respiratory rate < 8 per minute, patient unconscious or cyanosed |
|---|---|
| iv: | 0.1 to 0.2 mg every 2 to 3 minutes for reversal of CNS depression post-op 400 micrograms; if no response after 1 minute, give 800 micrograms, and if still no response after another 1 minute, repeat dose of 800 micrograms; if still no response, give 2 mg (4 mg may be required in a seriously poisoned patient), every 2 to 3 minutes up to 10 mg for opioid overdose |
| oral: | not available alone |
| subcut: | see below |
| rectal: | not available |
Syringe driver: not applicable
Mechanism of action: blocks action of opioids at opioid receptors
Onset: iv: 2 to 3 minutes subcut/im: 15 minutes
Duration: 15 to 90 minutes
Notes:
- best given iv, however if not practical can be given im or subcut
- reversal of respiratory depression will result in reversal of analgesia and withdrawal symptoms if physiologically dependent