Magnesium%252525252525252525252525252520sulfate

# Magnesium sulfate ## Overview Magnesium sulfate is an essential divalent cation. It acts as a calcium antagonist and physiological calcium channel blocker, impacting neuromuscular transmission and vascular smooth muscle tone. ## Primary Indications * **Eclampsia/Pre-eclampsia:** Prevention and control of seizures. * **Hypomagnesemia:** Treatment and prophylaxis. * **Torsades de Pointes/Arrhythmias:** Specifically documented with hypomagnesemia. * **Status Asthmaticus:** Adjunctive treatment for severe exacerbations. * **Fetal Neuroprotection:** Preterm labor (typically prior to 32 weeks). ## Adult Dosing * **Eclampsia/Pre-eclampsia:** Loading dose 4–6 g IV over 15–20 minutes, followed by 1–2 g/hour continuous infusion. * **Hypomagnesemia:** 1–4 g IV/IM. Severe cases (e.g., 1–2 g over 15 min). Maintenance: 0.5 g/hour or total daily dose 10–40 g depending on severity/renal function. * **Torsades de Pointes:** 1–2 g IV push (over 5–20 minutes); may repeat once. * **Status Asthmaticus:** 2 g IV bolus over 20 minutes (consult institutional guidelines). ## Pediatric Dosing * **Hypomagnesemia:** 25–50 mg/kg/dose IV/IM every 4–6 hours; max 2 g/dose. * **Status Asthmaticus:** 25–75 mg/kg IV (max 2 g) as a single dose over 20–30 minutes once other therapies fail. * *Note: Always verify dose based on institutional pediatric protocols.* ## Dose Adjustments * **Renal Impairment:** Reduce dose in patients with renal insufficiency. Magnesium is renally cleared. If CrCl <30 mL/min, use extreme caution; generally avoid or limit to 20 g/48 hours with frequent serum level monitoring. ## Contraindications * Myocardial block/heart block. * Severe renal impairment (CrCl <20 mL/min). * Myocardial damage. * Discontinue immediately if signs of toxicity (loss of patellar reflex, respiratory depression) occur. ## Adverse Effects * **Common:** Flushing, sweating, hypotension, sensation of warmth. * **Serious:** Respiratory depression, cardiac conduction abnormalities (prolonged PR/QRS/QT), areflexia, hypocalcemia. * **Toxicity:** Loss of deep tendon reflexes is the earliest clinical sign of hypermagnesemia. ## Key Drug Interactions * **Neuromuscular Blockers:** Potentiates effect; risk of prolonged paralysis. * **Aminoglycosides:** Additive neuromuscular blockade. * **Calcium Channel Blockers:** Enhances hypotensive effects and risk of cardiac conduction issues. * **Digoxin:** Concurrent use may increase risk of heart block. ## Monitoring * **Serum Magnesium:** Maintain therapeutic range (typically 1.7–2.3 mg/dL for general, 4.8–8.4 mg/dL for eclampsia). * **Clinical:** Assess deep tendon reflexes (hourly for obstetric patients), respiratory rate (>12 breaths/min), and urine output (>30 mL/hour). * **Toxicity Management:** Keep **calcium gluconate** at the bedside for immediate reversal of magnesium toxicity. ## Clinical Pearls * Rapid IV bolus administration can cause hypotension and arrhythmias. * Magnesium sulfate is not the same as magnesium oxide or other oral salts; IV dosing requires specific salt form calculations. * Always correlate serum levels with clinical symptoms. *** *Disclaimer: This information is for educational purposes only. Always consult current institutional guidelines, electronic medical records, and official prescribing information (e.g., package insert or clinical resources like Lexicomp/Micromedex) before prescribing or administering medication.*