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# Magnesium Sulphate
## Overview
Magnesium sulphate is an electrolyte used to treat magnesium deficiencies and as an anticonvulsant.
## Primary Indications
* Treatment of hypomagnesemia
* Prevention and treatment of seizures in preeclampsia and eclampsia
## Adult Dosing
* **Hypomagnesemia:**
* **Acute, symptomatic:** 4 to 6 g IV over 5 to 15 minutes, followed by an infusion of 1 to 2 g/hour.
* **Mild to moderate deficiency:** 1 g IM every 6 hours for 4 doses, or 5 g in 1 L of D5W or NS IV over 3 hours.
* **Preeclampsia/Eclampsia:**
* **Loading dose:** 4 to 6 g IV infused over 5 to 20 minutes.
* **Maintenance dose:** 1 to 2 g/hour IV infusion. Alternatively, 5 g IM in each buttock every 4 hours.
## Pediatric Dosing
Dosing is highly variable and depends on indication and magnesium level. Specific protocols are often followed. A general guideline for hypomagnesemia is 25-50 mg/kg IV over 10 minutes.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction and increased monitoring are necessary. Avoid in severe renal impairment.
## Contraindications
* Myocardial damage
* Heart block
* Hypermagnesemia
* Hypercalcaemia
* Severe renal impairment
## Adverse Effects
* Flushing, sweating, hypotension, nausea, vomiting, decreased reflexes, muscle weakness, respiratory depression, cardiac arrest.
## Key Drug Interactions
* **Calcium:** Can antagonize the cardiac and CNS depressant effects of magnesium.
* **Neuromuscular blocking agents:** May potentiate neuromuscular blockade.
* **Nifedipine:** Risk of profound hypotension and loss of neuromuscular tone.
## Monitoring
* Serum magnesium levels (especially with IV infusions and renal impairment)
* Deep tendon reflexes
* Respiratory rate
* Blood pressure
* Urine output
* ECG (if concerns for cardiac effects)
## Clinical Pearls
* Monitor for signs of hypermagnesemia (hyporeflexia, hypotension, respiratory depression).
* Ensure adequate renal function before administration.
* Have calcium gluconate readily available as an antidote for severe hypermagnesemia.
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**Disclaimer:** This information is intended for clinical professionals. Always consult the most current prescribing information and institutional protocols before making any treatment decisions.
