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Pure μ-opioid receptor antagonist

Naloxone hydrochloride

Brand names: Prenoxad, Nyxoid (intranasal), Narcan

Adult dose

Dose: Acute overdose: 0.4–2mg IV/IM/SC; repeat every 2–3 min, max 10mg before considering non-opioid cause. Infusion: 60% of dose-needed-to-reverse per hour. Intranasal (Nyxoid): 1.8mg into one nostril; repeat at 2–3 min if needed
Route: IV/IM/SC/Intranasal
Frequency: PRN

Clinical pearls

  • Suspected opioid overdose with respiratory depression
  • Short half-life (~30 min) — re-sedation common with long-acting opioids (methadone, MR formulations); infusion or repeated doses needed
  • Take-home naloxone for opioid users (community programme)

Contraindications

  • Hypersensitivity

Side effects

  • Acute opioid withdrawal
  • Tachycardia
  • Hypertension
  • Pulmonary oedema (rare)
  • Tachyarrhythmia

Interactions

  • Reverses all μ-opioid effects (analgesia + respiratory depression)

Monitoring

  • Respiratory rate
  • Conscious level
  • BP
  • HR

Reference: BNF; UK Resus Council; PHE/UK guidelines drug misuse; https://bnf.nice.org.uk/drugs/naloxone-hydrochloride/. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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