Opioid Antagonist Pregnancy: B — safe for maternal opioid overdose

Naloxone

Brand names: Narcan, Prenoxad, Nyxoid

Adult dose

Dose: 0.4–0.8mg IV, repeat every 2–3 min

Route: IV / IM / SC / Intranasal

Frequency: Every 2–3 min until adequate ventilation (RR >12/min)

Max: 10mg total — if no response, reconsider opioid aetiology

IN: 1.8mg (Nyxoid nasal spray) or 400mcg/0.1ml via MAD. IM: 400–800mcg. Infusion if long-acting opioid: 2/3 of effective bolus dose per hour.

Dose: 0.01 mg/kg

Route: IV / IM / Intranasal

Frequency: Every 2–3 min until adequate ventilation

Max: 0.4mg

Concentration: 0.4 mg/ml

Paediatric weight-based calculator

Patient weight (kg)

Duration of naloxone 45–90 min is SHORTER than most opioids. Re-sedation is common with diazepam, methadone, sustained-release opioids — observe minimum 2h after last dose.
In opioid-dependent patients: titrate to achieve RR >12/min, NOT full consciousness — precipitates severe withdrawal and violent agitation.
Community take-home naloxone (Prenoxad IM, Nyxoid IN): supply to patients on high-dose opioids and their families.
Buprenorphine (Subutex, Suboxone) reversal: up to 4mg IV required due to partial agonism and high receptor affinity.

Hypersensitivity to naloxone
Caution in opioid-dependent patients — precipitates acute withdrawal (violent agitation)

Reference: BNFc; NICE BNF 84; TOXBASE; NPIS; SIGN Opioid Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

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