Magnesium sulfate — FY prescribing 💊
🚨 HIGH ALERT — EDUCATIONAL DRAFT, NOT A PRESCRIBING ORDER. Drug choice, indication, formulation, dose, route and monitoring require current BNF/BNFC, product SmPC and local NHS protocol. Source reviewed 3 November 2026; independent clinical/pharmacy sign-off pending.
🧬 Mechanism and reason for use
- Magnesium regulates neuromuscular excitation and cardiac repolarisation; it can cause respiratory depression and heart block when given too rapidly or when it accumulates.
- Eclampsia; severe hypomagnesaemia; selected arrhythmias — each indication uses different doses.
💊 Indication-specific UK regimen / dosing boundary
- Eclampsia in a critical-care setting: NICE NG133 Collaborative Eclampsia Trial regimen 4 g IV over 5–15 minutes then 1 g/hour infusion for 24 h (24 h after last seizure if applicable). A recurrent eclamptic seizure may warrant 2–4 g IV over 5–15 minutes under obstetric protocol.
- Other indications: do NOT reuse the eclampsia regimen for torsades de pointes, asthma or hypomagnesaemia; consult their separate emergency pathways.
🔎 Before writing a prescription
- Confirm exact indication, renal function, respiratory status, reflexes, infusion concentration and pump settings.
🧪 Monitoring and reassessment
- Reflexes, respiratory rate, urine output and ECG where indicated; specialist magnesium levels if indicated.
🚨 Serious pitfalls / when to escalate
- Absent reflexes, hypoventilation or oliguria may signal toxicity; stop and seek urgent senior help.
- Pregnancy and obstetric use require maternity/anaesthetic team supervision.
📖 UK reference documents
Editorial status: Source checked for the specific statements above on 3 November 2026. References may be updated. This card has not had formal independent pharmacist/consultant approval; no unlisted indications, paediatric extrapolation or automatic renal-dose adjustments are implied.
