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# Magnesium Sulphate
## Overview
Magnesium sulphate is an electrolyte that plays a vital role in numerous physiological processes, including neuromuscular function, cardiac contractility, and enzyme activity.
## Primary Indications
* Treatment of hypomagnesemia
* Management of eclampsia and severe preeclampsia
* Treatment of torsades de pointes
* Management of status epilepticus refractory to standard therapy
* Adjunctive therapy for bronchospasm in severe asthma
## Adult Dosing
**Hypomagnesemia:**
* **Acute symptomatic:** 4-6 g IV infusion over 5-10 minutes, followed by 1-2 g/hour as a continuous infusion. May be repeated every 4 hours as needed.
* **Asymptomatic:** 1-6 g IM or IV every 6 hours for 4 doses.
**Eclampsia/Severe Preeclampsia:**
* **Loading dose:** 4-6 g IV infusion over 5-10 minutes.
* **Maintenance infusion:** 1-2 g/hour IV infusion.
* **Alternative IM dosing:** 5 g IM in alternating buttocks every 4 hours.
**Torsades de Pointes:**
* 1-2 g IV diluted in 10 mL D5W given as a rapid IV injection or over 5-10 minutes. Followed by an infusion of 0.5-1 g/hour.
**Status Epilepticus (refractory):**
* Dosing varies widely based on protocol, often 1-4 g IV.
**Bronchospasm (severe asthma):**
* 1-2 g IV diluted in 100 mL NS over 15-30 minutes.
## Pediatric Dosing
**Hypomagnesemia:**
* Dosing is based on weight and severity, often ranging from 25-100 mg/kg/dose IV or IM, not to exceed 2 g per dose. A continuous infusion of 50-100 mg/kg/hour may be used.
**Eclampsia/Severe Preeclampsia:**
* Dosing is typically based on adult protocols, but specific pediatric guidelines may be followed.
**Torsades de Pointes:**
* 25-100 mg/kg IV, not to exceed 2 g.
**Status Epilepticus (refractory):**
* Dosing varies widely based on protocol.
## Dose Adjustments
No specific dose adjustment for renal impairment is typically recommended, but caution is advised as magnesium is renally excreted. In severe renal impairment, doses should be reduced and serum magnesium levels closely monitored.
## Contraindications
* Hypermagnesemia
* Heart block greater than first degree (unless a temporary pacemaker is in place)
* Myocardial infarction
* Shock
## Adverse Effects
* **Common:** Flushing, diaphoresis, hypotension, decreased deep tendon reflexes, somnolence.
* **Serious:** Respiratory depression, cardiac arrest, hypermagnesemia (especially in renal impairment), absent deep tendon reflexes, ECG changes.
## Key Drug Interactions
* **Neuromuscular blockers:** Increased neuromuscular blockade.
* **Calcium channel blockers:** Potential for additive hypotension and cardiovascular depression.
* **Nifedipine:** Increased risk of hypotension.
## Monitoring
* **Essential:** Serum magnesium levels, deep tendon reflexes, respiratory rate, blood pressure, and urine output.
* **Consider:** ECG, renal function.
## Clinical Pearls
* Administer IV infusions slowly to avoid hypotension and respiratory depression.
* Monitor for signs of hypermagnesemia, especially in patients with impaired renal function.
* Have calcium gluconate readily available as an antidote for severe magnesium toxicity.
* Dosing for eclampsia and refractory status epilepticus may vary based on local hospital protocol.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information, institutional protocols, and clinical judgment before making any treatment decisions. Drug information can change rapidly.*
