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# Magnesium Sulphate
## Overview
Magnesium sulphate is an essential mineral that plays a vital role in numerous biochemical reactions. It is administered parenterally for various indications.
## Primary Indications
* Treatment of hypomagnesemia.
* Management of severe preeclampsia and eclampsia.
* Treatment of torsades de pointes.
* Adjunctive therapy in status asthmaticus.
## Adult Dosing
* **Hypomagnesemia:**
* **Severe deficiency:** 4 to 6 g IV infused over 5 to 15 minutes, followed by 1 to 2 g/hour infusion. Dosing may be adjusted based on serum magnesium levels and clinical response.
* **Less severe deficiency:** 1 g IV every 12 hours for 4 doses.
* **Preeclampsia/Eclampsia:** Loading dose: 4 to 6 g IV infused over 5 to 20 minutes. Maintenance infusion: 1 to 2 g/hour. Dosing may vary per institutional protocol.
* **Torsades de Pointes:** 1 to 2 g IV in 10 mL of D5W over 1 to 2 minutes. May repeat every 5 minutes. Further doses may be given as continuous infusion of 0.5 to 1 g/hour.
* **Status Asthmaticus:** 25 to 50 mg/kg IV, maximum 2 g, infused over 15 minutes.
## Pediatric Dosing
* **Hypomagnesemia:** 25 to 50 mg/kg/dose IV every 12 hours for 4 doses. Maximum dose per administration is 2 g.
* **Status Asthmaticus:** 25 to 50 mg/kg IV, maximum 2 g, infused over 15 minutes. Dosing protocols may vary.
## Dose Adjustments
Reduce dose in patients with impaired renal function. Close monitoring of urine output is essential. Avoid in patients with anuria or severe renal impairment.
## Contraindications
* Hypermagnesemia.
* Heart block or myocardial damage.
* Hypersensitivity to magnesium sulphate.
## Adverse Effects
Common adverse effects include flushing, sweating, hypotension, nausea, vomiting, and decreased deep tendon reflexes. More serious effects include respiratory depression, cardiac arrhythmias, and coma.
## Key Drug Interactions
* **Neuromuscular Blocking Agents:** May potentiate neuromuscular blockade.
* **Calcium Salts:** May antagonize the effects of magnesium.
* **Potassium-Sparing Diuretics:** Increased risk of hypermagnesemia.
* **Tetracyclines and Quinolones:** Magnesium may decrease absorption; separate administration by at least 2 hours.
## Monitoring
* **Serum Magnesium Levels:** Monitor closely, especially during IV infusion. Target levels vary by indication.
* **Renal Function:** Assess baseline and monitor for changes.
* **Respiratory Rate and Depth:** Monitor for signs of respiratory depression.
* **Deep Tendon Reflexes:** Assess for loss of reflexes, indicating hypermagnesemia.
* **Blood Pressure and Heart Rate:** Monitor for hypotension and arrhythmias.
* **Urine Output:** Monitor closely, especially in renal impairment.
## Clinical Pearls
* Always dilute magnesium sulphate for IV infusion to avoid rapid administration and potential adverse effects.
* Ensure calcium gluconate is readily available as an antidote in case of severe toxicity.
* Be aware of institutional protocols, as specific dosing regimens can vary, particularly for eclampsia and status asthmaticus.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional guidelines before administering any medication.*
