AlternativeDiamorphine (generic)
Diamorphine
Opioid — prodrug of morphine
IM labour analgesia — long UK obstetric heritage.
IMIVSCIntrathecal
First-line for
- Labour analgesia (IM)
- Intrathecal analgesia during LSCS
- Palliative severe pain
Mechanism
Rapidly deacetylated to 6-MAM then morphine → μ-opioid agonism.
"Diamorphine = deep and drowsy — deliver naloxone-ready"
- Onset IM 20–30 min, duration 3–4 h
- Neonatal respiratory depression — Naloxone available
- Delays 1st-stage progress modestly
Dosing
- IM labour
- 5–7.5 mg IM 4-hourly PRN
- Intrathecal (LSCS)
- 300–400 μg
Contraindications
- AbsoluteRespiratory failure
- AbsoluteHead injury / raised ICP
- AbsoluteSuspected imminent delivery (<1 h)
Side effects
- Respiratory depression
- Sedation, nausea, vomiting
- Pruritus (intrathecal)
- Neonatal respiratory depression
Fetal & maternal notes
- • Crosses placenta — timing critical; avoid within 4 h of delivery if possible
- • Neonatal Apgar and respiration monitored; Naloxone 10 μg/kg IM if needed
Key interactions
Benzodiazepines / alcohol
AvoidRespiratory depression
MAOIs
AvoidSerotonin syndrome / severe hypotension
Clinical pearls
- 💡 Combine with cyclizine or ondansetron for nausea
- 💡 Document maternal and fetal HR before and after each dose
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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