Magnesium%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulfate ## Overview Magnesium sulfate is an essential mineral that plays a crucial role in various enzymatic reactions, neuromuscular transmission, and cardiac function. It is available in intravenous (IV) and intramuscular (IM) formulations. ## Primary Indications * **Eclampsia/Preeclampsia:** Prevention and treatment of seizures in severe preeclampsia and eclampsia. * **Hypomagnesemia:** Treatment of magnesium deficiency. * **Torsades de Pointes:** Management of polymorphic ventricular tachycardia associated with a prolonged QT interval. * **Bronchospasm:** Adjunctive therapy for severe acute asthma or COPD exacerbations refractory to standard bronchodilators and corticosteroids. ## Adult Dosing * **Eclampsia/Preeclampsia:** * **Loading Dose:** 4-6 grams IV infused over 15-30 minutes. * **Maintenance Dose:** 1-2 grams/hour IV infusion. Alternatively, 5 grams IM in each buttock every 4 hours if IV access is not feasible. * **Hypomagnesemia:** * **Severe Symptomatic (e.g., seizures, arrhythmias):** 4 grams IV infused over 5-10 minutes, followed by maintenance infusion of 1-2 grams/hour. * **Asymptomatic:** 2-4 grams IM divided into 2 doses every 4-6 hours for 24 hours, or 1-2 grams/hour IV infusion. * **Torsades de Pointes:** 1-2 grams IV diluted in 10 mL D5W or NS, infused rapidly over 5-10 minutes. May repeat every 5-15 minutes. Subsequent infusion of 0.5-1 gram/hour may be needed. * **Bronchospasm:** 2 grams IV infused over 15-20 minutes. ## Pediatric Dosing Dosing in pediatrics is less standardized and often based on weight and clinical condition. Local protocols should be consulted. * **Hypomagnesemia:** Typically 25-50 mg/kg/dose IV infused over 10-20 minutes, not to exceed 2 grams per dose. Maintenance infusions may range from 0.2-0.5 mEq/kg/hour (approximately 12-30 mg elemental magnesium/kg/hour). * **Eclampsia:** Use adult dosing regimens if weight-appropriate. * **Bronchospasm:** 25-40 mg/kg/dose IV infused over 15-30 minutes, not to exceed 2 grams per dose. ## Dose Adjustments * **Renal Impairment:** Magnesium is renally excreted. In patients with renal insufficiency, serum magnesium levels should be closely monitored. Reduce dose and/or frequency as indicated. In severe renal impairment, administration may be contraindicated. * **Hepatic Impairment:** No specific dose adjustment is usually required. ## Contraindications * Hypersensitivity to magnesium sulfate. * Hypermagnesemia. * Heart block or myocardial damage. * Severe renal impairment. ## Adverse Effects * **Common:** Flushing, sweating, hypotension, somnolence, nausea, vomiting. * **Serious:** Respiratory depression, cardiac arrest, hyperreflexia, absent reflexes, arrhythmias, hyperthermia, muscle weakness, hypothermia. ## Key Drug Interactions * **Neuromuscular Blockers:** Magnesium can potentiate the effects of non-depolarizing neuromuscular blockers, potentially leading to prolonged paralysis. * **Calcium Salts:** IV calcium may be used as an antidote in severe magnesium toxicity. * **Antibiotics (Tetracyclines, Quinolones):** Magnesium may decrease the absorption of oral tetracyclines and fluoroquinolones by forming insoluble complexes; separate administration by at least 2 hours. ## Monitoring * **Therapeutic:** Assess for resolution of symptoms (e.g., seizure cessation, improved cardiac rhythm, reduced bronchospasm). * **Toxicity:** Monitor respiratory rate, deep tendon reflexes, urine output, blood pressure, and electrocardiogram (ECG). * **Laboratory:** Monitor serum magnesium levels, particularly during prolonged infusions or in patients with renal impairment. Target serum magnesium levels vary by indication but often range from 4-7 mEq/L (2-3.5 mmol/L) for eclampsia/preeclampsia and 4-8 mEq/L (2-4 mmol/L) for hypomagnesemia. Monitor renal function (creatinine). ## Clinical Pearls * Magnesium sulfate is administered as elemental magnesium. Ensure correct calculation of elemental magnesium when converting between different salt forms or concentrations. * Rapid IV infusion can cause hypotension and flushing. Infuse as directed. * Loss of deep tendon reflexes is an early sign of magnesium toxicity, followed by respiratory depression and cardiac arrest. * IV calcium gluconate is the antidote for severe magnesium toxicity. * In preeclampsia/eclampsia, continuous monitoring is essential due to the risk of toxicity and recurrence of seizures. *** *This information is intended for healthcare professionals. Always verify current prescribing information and consult with a qualified healthcare provider before making any treatment decisions.*