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Opioid Analgesic (Short-Acting — Perioperative) Pregnancy: Intraoperative use acceptable; fetal respiratory depression if given close to delivery

Fentanyl (Perioperative Analgesia)

Brand names: Sublimaze (IV), Durogesic (patch)

Adult dose

Dose: IV intraoperative: 1–3 mcg/kg slow IV bolus at induction; titrate with 25–50 mcg increments during surgery. Patch (chronic): 12–100 mcg/hr every 72h (opioid-tolerant patients only)
Route: IV (intraoperative) or transdermal patch
Frequency: Bolus as needed intraoperatively; patch every 72h
Max: Titrate to response — no fixed ceiling in opioid-tolerant patients under anaesthesia
Highly lipid-soluble — rapid onset (1–2 min), short duration (30–60 min IV bolus). Context-sensitive half-life increases with prolonged infusion. Patch: NOT for acute pain or opioid-naïve patients — patch only for chronic opioid-tolerant patients.

Paediatric dose

Dose: 1 mcg/kg
Route: IV slow bolus
Frequency: Intraoperative bolus; repeat 0.5–1 mcg/kg PRN
Max: 5 mcg/kg total intraoperative dose
Concentration: 50 mcg/mL mcg/ml
Children: 1–4 mcg/kg slow IV over 3–5 min. Neonates: 1–2 mcg/kg — careful dose titration required. Nasal fentanyl (intranasal): 1.5–2 mcg/kg for procedural pain in children.

Dose adjustments

Renal

Dose with caution in renal impairment — metabolite accumulation

Hepatic

Reduce dose in severe hepatic impairment

Paediatric weight-based calculator

Children: 1–4 mcg/kg slow IV over 3–5 min. Neonates: 1–2 mcg/kg — careful dose titration required. Nasal fentanyl (intranasal): 1.5–2 mcg/kg for procedural pain in children.

Clinical pearls

  • Chest wall rigidity ('wooden chest'): avoid rapid large bolus — give slowly, especially >3 mcg/kg; treat with suxamethonium if needed
  • Context-sensitive half-life: short for bolus but prolongs significantly with infusions >2h — recovery delayed
  • Patch safety: only for opioid-tolerant patients; never apply to non-tolerant patients — fatal respiratory depression reported
  • Intrathecal fentanyl (25 mcg): provides excellent rapid-onset analgesia without significant haemodynamic effects — widely used in obstetric spinals
  • Naloxone reversal: fentanyl is naloxone-reversible — ensure naloxone available perioperatively

Contraindications

  • Respiratory depression without ventilatory support
  • Raised intracranial pressure (bolus increases ICP transiently)
  • Patch: opioid-naïve patients, acute pain, altered conscious level

Side effects

  • Respiratory depression (dose-dependent)
  • Chest wall rigidity (rapid large IV bolus — 'wooden chest')
  • Bradycardia
  • Nausea/vomiting
  • Sedation
  • Pruritus (especially intrathecal)

Interactions

  • CNS depressants — additive respiratory depression
  • MAOIs — serotonin syndrome risk
  • CYP3A4 inhibitors (azole antifungals) — increased fentanyl levels (patch)

Monitoring

  • Respiratory rate and SpO2
  • Level of consciousness (sedation score)
  • HR and BP
  • Pain score

Reference: BNFc; BNF; RCoA Acute Pain Handbook; ANZCA Opioid Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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