Please check your internet connection and try again.
# Magnesium sulfate
## Overview
Magnesium sulfate is an electrolyte supplement and anticonvulsant. It acts as a calcium antagonist and inhibits neuromuscular transmission. It is typically administered via IV or IM routes; oral administration is generally reserved for laxative use (not covered here).
## Primary Indications
* **Eclampsia/Preeclampsia:** Prevention and control of seizures.
* **Torsades de Pointes/Arrhythmias:** Management of life-threatening ventricular arrhythmias.
* **Severe Hypomagnesemia:** Replacement therapy.
* **Acute Severe Asthma:** Adjunctive therapy for bronchodilation.
## Adult Dosing
* **Eclampsia/Preeclampsia:** 4–6 g IV loading dose over 15–20 minutes, followed by a maintenance infusion of 1–2 g/hour. Follow institutional protocols.
* **Torsades de Pointes:** 1–2 g IV push over 5–20 minutes; may repeat once if rhythm persists.
* **Hypomagnesemia:** 1–4 g IV (depending on severity) administered over 4–6 hours; may repeat based on serum levels.
* **Acute Severe Asthma:** 2 g IV bolus over 20 minutes (off-label).
## Pediatric Dosing
* **Hypomagnesemia:** 25–50 mg/kg/dose IV every 6 hours for 3–4 doses. Maximum 2 g/dose.
* **Acute Severe Asthma:** 25–50 mg/kg IV bolus over 20–30 minutes. Maximum 2 g.
* **Torsades de Pointes:** 25–50 mg/kg/dose IV. Maximum 2 g.
## Dose Adjustments
* **Renal Impairment:** Reduce dose and frequency significantly in patients with CrCl <30 mL/min or elevated serum creatinine. High risk of accumulation and toxicity.
## Contraindications
* Heart block (unless pacemaker present).
* Myocardial damage.
* Severe renal impairment (with hypermagnesemia).
* Hypersensitivity to magnesium.
## Adverse Effects
* **Early signs:** Flushing, sweating, hypotension, depressed deep tendon reflexes (DTRs).
* **Severe:** Respiratory depression, cardiac arrest, AV block, hypocalcemia.
* **Toxicity management:** Stop infusion immediately. Administer **Calcium gluconate** (1 g IV) to reverse respiratory depression/cardiac toxicity.
## Key Drug Interactions
* **Neuromuscular Blockers:** Potentiates effects; increases risk of prolonged paralysis.
* **CNS Depressants:** Enhances sedation.
* **Aminoglycosides:** May potentiate neuromuscular blockade.
* **Digoxin:** Rapid administration may cause cardiac conduction changes.
## Monitoring
* **Reflexes:** Hourly assessment of patellar reflexes (loss of DTRs is an early sign of toxicity).
* **Respiratory:** Monitor rate (do not administer if <12 bpm).
* **Renal:** Urine output (minimum 0.5 mL/kg/hour).
* **Serum Levels:** Target therapeutic range for eclampsia is typically 4–7 mEq/L (4.8–8.4 mg/dL). Obtain levels as per institutional protocol.
## Clinical Pearls
* Rapid IV bolus injection can cause profound hypotension and asystole. Always dilute and use an infusion pump.
* Magnesium is cleared renally; always check baseline renal function.
* In asthma, magnesium sulfate is reserved for patients who fail to respond to standard inhaled beta-agonists and corticosteroids.
***
**Educational Disclaimer:** This information is for educational purposes only. Clinical practice varies by institution and patient-specific factors. Always verify current prescribing information, dosing protocols, and compatibility via institutional guidelines or official product labeling before administration.
