Naloxone (Narcan) Opiate antagonist 💊
Related Subjects:
|Sedation and Analgesia on ITU
|Neuropathic Pain Management
|Codeine
|Dihydrocodeine
|Diamorphine
|Morphine
|Paracetamol (Acetaminophen)
|Tramadol
|Naloxone (Narcan) Opiate antagonist
💡 Much smaller doses are given to reverse opiate excess in those on palliation, as sudden complete reversal may precipitate severe pain.
🚑 Naloxone is the emergency antidote for overdoses caused by heroin and other opioids (morphine, methadone, fentanyl).
⚠️ Reversal of buprenorphine-induced respiratory depression may be incomplete.
📖 About
- Always check the BNF link here for up-to-date prescribing advice.
- Opiate antagonist → rapidly reverses opioid-induced respiratory and CNS depression.
- Onset is rapid (minutes IV), but duration is short (30–90 mins) → monitor for rebound toxicity, esp. with long-acting opioids.
⚙️ Mode of Action
- Half life about 1 hr shorter than many opiates
- Competitive antagonist at mu-opioid receptors (also kappa and delta).
- Displaces opioids from receptors → reversal of respiratory depression, sedation, and analgesia.
💉 Indications / Doses (Adults)
| Formulation | Starting Dose | Frequency | Route |
|---|
| Opioid toxicity (standard) | 400 micrograms (0.4 mg) | Repeat q2–3 mins up to 2–4 mg (larger doses may be needed) | IV |
| Opioid toxicity (standard) | Add 2 mg to 500 ml Dextrose or NS and titrate to run infusion to level of coma | Titrate | IV |
| Opioid toxicity (alternative) | 400 micrograms (0.4 mg) | Repeat as required | IM (deltoid or anterolateral thigh) |
| Opioid toxicity (palliative care) | 100–200 micrograms (0.1–0.2 mg) | Repeat slowly | IV/IM (avoid full reversal if severe pain/withdrawal risk) |
| Opioid toxicity (community use) | 1.8 mg | Repeat after 2–3 mins if no response | Intranasal spray |
⚠️ Cautions
- Risk of acute withdrawal syndrome if reversal is too rapid in opioid-dependent patients.
- Can precipitate severe pain, agitation, hypertension, arrhythmias, pulmonary oedema, or cardiac arrest in frail/elderly patients.
- Duration of action shorter than many opioids → monitor closely for relapse.
💊 Side Effects
- ❤️ Arrhythmias (including VT, esp. in elderly)
- 😵 Dizziness, headache
- ⬆️ Hypertension / ⬇️ Hypotension
- 🤢 Nausea, vomiting
- 💨 Pulmonary oedema (rare but serious)
📚 References
