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Opioid Analgesic — Strong Pregnancy: Use with caution — opioids cross placenta; neonatal withdrawal syndrome and respiratory depression; avoid near term

Morphine (Orthopaedic Acute Pain)

Brand names: Oramorph, MST Continus, Sevredol, Morphgesic

Adult dose

Dose: Oral immediate release: 5–10 mg every 4 hours; IV: 2.5–5 mg every 4 hours titrated; IM: 5–10 mg every 4 hours
Route: Oral, IV, or IM
Frequency: Every 4 hours (IR) or every 12 hours (SR)
Max: No ceiling dose — titrate to pain; typical acute post-fracture doses 10–30 mg/day total
WHO analgesic ladder Step 3. Always prescribe laxative with regular opioid — opioid-induced constipation is universal. Prescribe anti-emetic (metoclopramide or ondansetron) for first 72 hours. IV morphine preferred in acute severe trauma. Reduce dose in elderly by 25–50%.

Paediatric dose

Dose: 0.1–0.2 mg/kg
Route: IV or Oral
Frequency: Every 4 hours
Max: 10 mg per dose
Paediatric fracture pain — weight-based dosing essential; IV titration preferred for acute severe pain

Dose adjustments

Renal

Reduce dose and frequency in renal impairment — morphine-6-glucuronide (active metabolite) accumulates; can cause respiratory depression

Hepatic

Reduce dose in moderate-severe hepatic impairment — reduced first-pass metabolism

Paediatric weight-based calculator

Paediatric fracture pain — weight-based dosing essential; IV titration preferred for acute severe pain

Clinical pearls

  • MHRA 2017: Concurrent use of opioids and gabapentinoids (gabapentin, pregabalin) significantly increases risk of fatal respiratory depression — review all prescriptions for this combination; assess risk in elderly and respiratory disease
  • Morphine-6-glucuronide (M6G) is 3–4× more potent than morphine itself — accumulates in renal failure causing prolonged respiratory depression. Oxycodone or tramadol may be preferable in CKD
  • ERAS (Enhanced Recovery After Surgery) protocols: minimise opioid use — multimodal analgesia (paracetamol + NSAID + regional block) reduces opioid requirements by 30–50%
  • Acute femoral neck fracture: fascia iliaca block (0.25% bupivacaine 40 mL) provides excellent pre-operative analgesia and reduces IV morphine requirement — recommended by NICE NG124
  • Naloxone (Narcan) 400 mcg IV is the reversal agent — repeat every 2–3 minutes up to 10 mg; short half-life (30–90 min) means repeat dosing or infusion may be needed

Contraindications

  • Acute respiratory depression
  • Raised intracranial pressure (modifies clinical assessment)
  • Paralytic ileus
  • Head injury (acute)

Side effects

  • Constipation — universal; always co-prescribe laxative
  • Nausea and vomiting — especially early
  • Respiratory depression — dose-dependent; risk highest in opioid-naive elderly
  • Sedation and delirium — particularly in elderly
  • Urinary retention
  • Pruritus (particularly with intrathecal morphine)
  • Addiction (prolonged use)

Interactions

  • CNS depressants (benzodiazepines, gabapentinoids, alcohol) — additive respiratory depression; MHRA 2017 warning for gabapentinoid + opioid combination
  • MAO inhibitors — severe serotonin syndrome or hyperpyrexia; avoid within 14 days
  • CYP3A4 inhibitors — may increase morphine levels

Monitoring

  • Respiratory rate and oxygen saturation
  • Sedation score
  • Pain score (NRS 0–10)
  • Bowel function
  • Urinary output

Reference: BNFc; BNF 90; NICE NG124 (Hip Fracture); MHRA Drug Safety Update 2017 (Gabapentinoids + Opioids); ERAS Society 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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