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Ultra-Short Acting Opioid Analgesic Pregnancy: Use with caution at delivery — rapid neonatal clearance expected; ensure resuscitation available

Remifentanil

Brand names: Ultiva

Adult dose

Dose: 0.05-2 micrograms/kg/min IV infusion (TIVA/intraoperative); 0.025-0.2 micrograms/kg/min (sedation)
Route: Intravenous infusion
Frequency: Continuous infusion
Max: Titrated to effect; bolus doses: 0.25-1 microgram/kg over 30 seconds
Must be used with appropriate ventilatory support. Dilute to 20-50 micrograms/mL for infusion. STOP at end of surgery — no residual analgesia; ensure adequate long-acting analgesia established before stopping

Paediatric dose

Dose: 0.05-1 microgram/kg/min IV infusion micrograms/min/kg
Route: IV infusion
Frequency: Continuous intraoperative
Max: Titrated to effect
Child 1 month to 11 years: 0.05-0.3 micrograms/kg/min. Adolescent: same as adult. Neonates: specialist use only

Dose adjustments

Renal

No dose adjustment — ester hydrolysis by plasma esterases, not organ-dependent

Hepatic

No dose adjustment — not hepatically metabolised

Paediatric weight-based calculator

Child 1 month to 11 years: 0.05-0.3 micrograms/kg/min. Adolescent: same as adult. Neonates: specialist use only

Clinical pearls

  • Unique pharmacokinetics: metabolised by non-specific plasma and tissue esterases — context-sensitive half-time remains approximately 3-4 minutes regardless of infusion duration; no accumulation
  • Post-operative analgesia MUST be planned before stopping remifentanil — its offset is so rapid that patients can wake in severe pain; multi-modal analgesia (paracetamol, NSAID, morphine) should be given intraoperatively
  • Opioid-induced hyperalgesia (OIH): paradoxical increase in pain sensitivity after prolonged remifentanil — ketamine co-infusion (0.1-0.5 mg/kg/hr) partially prevents this
  • Antidote: naloxone (as for all opioids) — but given remifentanil's ultra-short action, maintaining ventilation is usually sufficient
  • Ideal for procedures requiring fine titration of analgesia (neurosurgery, awake craniotomy, laparoscopic surgery) and where rapid emergence is needed

Contraindications

  • Use without facilities for immediate intubation and ventilation
  • Epidural or intrathecal administration

Side effects

  • Respiratory depression (profound, rapid)
  • Muscle rigidity (chest wall — high doses)
  • Bradycardia and hypotension
  • Opioid-induced hyperalgesia (OIH — prolonged or high-dose use causes paradoxical pain sensitisation post-op)

Interactions

  • Anaesthetic agents (significant synergy — propofol, volatiles; reduce requirements by 30-50%)
  • Other opioids (additive respiratory depression)

Monitoring

  • Continuous SpO2 and end-tidal CO2
  • Blood pressure
  • Heart rate
  • Level of consciousness

Reference: BNFc; BNF 90; Ultiva SPC; Minto et al. (1997) PK model; AAGBI 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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