Magnesium%252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is a parenteral mineral supplement and anticonvulsant. It acts as a calcium antagonist and reduces acetylcholine release at the neuromuscular junction. Pharmacokinetics vary significantly by clinical indication (e.g., eclampsia vs. arrhythmia). ## Primary Indications * **Eclampsia/Pre-eclampsia:** Prevention and control of seizures. * **Hypomagnesemia:** Replacement for symptomatic deficiency. * **Torsades de Pointes:** First-line treatment for polymorphic ventricular tachycardia. * **Severe Asthma:** Adjunctive therapy for acute exacerbations (refractory). ## Adult Dosing * **Eclampsia/Pre-eclampsia:** 4–6 g IV loading dose over 15–20 minutes, followed by 1–2 g/hour continuous infusion. * **Torsades de Pointes (with pulse):** 1–2 g IV/IO over 5–20 minutes. * **Hypomagnesemia (severe/symptomatic):** 1–2 g IV over 15–60 minutes. May repeat as needed. * **Acute Asthma:** 2 g IV over 20 minutes (single dose). ## Pediatric Dosing * **Hypomagnesemia:** 25–50 mg/kg/dose IV/IM; may repeat q4–6h. * **Acute Asthma:** 25–50 mg/kg/dose IV (max 2 g) over 20 minutes. * *Note: Always consult institutional guidelines or standardized pediatric dosing resources (e.g., Lexicomp/NeoFax) for neonates and specific weight-based protocols.* ## Dose Adjustments * **Renal Impairment:** Reduce infusion rate by 50% or avoid if CrCl <30 mL/min. Magnesium levels accumulate rapidly in renal failure; monitor serum concentrations frequently. ## Contraindications * Myasthenia gravis (may precipitate crisis). * Heart block. * Myocardial damage. * Severe renal impairment (unless strictly monitored for life-threatening conditions). ## Adverse Effects * **Common:** Flushing, sweating, hypotension, warmth/burning at injection site. * **Toxicity (Dose-Related):** Loss of deep tendon reflexes (early sign), respiratory depression (<12 breaths/min), conduction abnormalities (bradycardia, AV block), cardiac arrest. ## Key Drug Interactions * **Neuromuscular Blocking Agents:** Potentiates effects; increases risk of prolonged paralysis. * **CNS Depressants:** Enhances sedative effects. * **Aminoglycosides:** Potentiates peripheral neuromuscular blockade. * **Digoxin:** Use caution; may lead to conduction blocks. ## Monitoring * **Serum Magnesium:** Target 1.5–2.5 mEq/L for deficiency; 4–7 mEq/L for eclampsia. * **Clinical Signs:** Evaluate deep tendon reflexes (patellar reflex), respiratory rate (>12 breaths/min), and urine output (>30 mL/hr) every hour during infusion. * **Antidote:** **Calcium Gluconate 1 g IV** must be immediately available at the bedside to treat respiratory depression or cardiac toxicity. ## Clinical Pearls * **Rapid Bolus:** Rapid IV administration of bolus doses (beyond recommended infusion rates) can lead to cardiac arrest or hypotension. * **Extravasation:** High concentrations can cause tissue necrosis; ensure IV patency prior to administration. * **Local Protocols:** Eclampsia dosing protocols (Zuspan vs. Sibai) vary by institution; always adhere to the specific order set in place. *** *Disclaimer: This information is for educational purposes and does not substitute for clinical judgment. Always verify current dosing and safety information through local hospital guidelines and official prescribing information (package inserts) before administration.*