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Opioid Analgesic (Moderate-Strong) Pregnancy: Avoid in third trimester — neonatal respiratory depression; avoid in labour

Oxycodone

Brand names: OxyNorm, OxyContin (modified release)

Adult dose

Dose: 5-10 mg oral every 4-6 hours (immediate release); 10-40 mg twice daily (modified release); 1-10 mg IV slowly
Route: Oral / Intravenous
Frequency: Every 4-6 hours (IR); twice daily (MR)
Max: Titrated to pain; avoid high doses without specialist review
Approximately 1.5-2x more potent than oral morphine. Oral bioavailability approximately 60-80% (vs morphine 30%). PCA: 1-2 mg bolus with 5-min lockout

Paediatric dose

Dose: 0.05-0.1 mg/kg oral every 4-6 hours mg/kg
Route: Oral
Frequency: Every 4-6 hours
Max: 5 mg per dose
Child 12 years and over: adult dosing. Under 12: seek specialist opinion

Dose adjustments

Renal

Reduce dose in renal impairment — oxymorphone (active metabolite) accumulates; prefer immediate-release and monitor closely

Hepatic

Reduce dose by 50% and extend interval in moderate-severe hepatic impairment

Paediatric weight-based calculator

Child 12 years and over: adult dosing. Under 12: seek specialist opinion

Clinical pearls

  • Antidote: naloxone — as for all opioids; dose same as morphine reversal
  • Higher oral bioavailability than morphine (60-80% vs 30%) — more predictable plasma levels; preferred for post-operative oral analgesia step-down
  • Modified release oxycodone (OxyContin): do not crush or chew — designed for 12-hourly dosing; crushing releases entire dose (overdose risk)
  • MHRA: Opioid abuse potential — oxycodone has particular abuse liability; prescribe minimum effective dose for shortest duration; review regularly
  • Opioid rotation: if patient on morphine with unacceptable side effects, converting to oxycodone (divide morphine dose by 1.5-2) may improve tolerability

Contraindications

  • Acute respiratory depression
  • Paralytic ileus
  • Concurrent MAOI use
  • Acute abdomen (relative)

Side effects

  • Nausea and vomiting
  • Constipation
  • Sedation
  • Respiratory depression
  • Dependence and addiction
  • Pruritus
  • Urinary retention

Interactions

  • CNS depressants (additive)
  • MAOIs (serotonin syndrome)
  • CYP3A4 inhibitors (increase oxycodone exposure)
  • CYP2D6 inhibitors (reduce oxymorphone formation — reduce analgesia)

Monitoring

  • Pain scores
  • Respiratory rate and SpO2
  • Sedation score
  • Bowel function
  • Signs of dependence

Reference: BNFc; BNF 90; OxyNorm SPC; FACULTY of Pain Medicine Opioid Prescribing Guidelines; PROSPECT 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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