Magnesium%252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulfate is an electrolyte supplement and anticonvulsant. It is available in various formulations, including intravenous (IV) and intramuscular (IM) solutions, as well as oral formulations. ## Primary Indications * Treatment of hypomagnesemia. * Prevention and treatment of seizures in preeclampsia and eclampsia. * Management of torsades de pointes. * Management of status asthmaticus (off-label in some regions, consult local protocol). ## Adult Dosing **Hypomagnesemia:** * **Severe deficiency (serum magnesium < 1.5 mEq/L or 0.75 mmol/L):** * **IV:** 4 to 5 g (32 to 40 mEq or 16 to 20 mmol) infused over 5 to 60 minutes, followed by a continuous infusion of 1 to 2 g/hour (8 to 16 mEq or 4 to 8 mmol) for up to 24 hours or until serum magnesium levels are therapeutic. * **IM:** 1 to 5 g (8 to 40 mEq or 4 to 20 mmol) every 4 hours as needed. * **Less severe deficiency:** Dosing may be adjusted based on serum magnesium levels and clinical presentation. Consult local protocol. **Preeclampsia/Eclampsia Prophylaxis and Treatment:** * **Loading Dose (IV):** 4 to 6 g (32 to 48 mEq or 16 to 24 mmol) infused over 15 to 20 minutes. * **Maintenance Dose (IV):** 1 to 2 g/hour (8 to 16 mEq or 4 to 8 mmol) as a continuous infusion. * **Alternative IM dosing:** 5 g (40 mEq or 20 mmol) IM into each buttock (total 10 g) for the loading dose, followed by 5 g (40 mEq or 20 mmol) IM every 4 hours. **Torsades de Pointes:** * **IV:** 1 to 2 g (8 to 16 mEq or 4 to 8 mmol) diluted in 10 to 20 mL of D5W or normal saline, infused over 5 to 10 minutes. May repeat doses. Continuous infusion may be considered. ## Pediatric Dosing Dosing in children is highly variable and depends on the indication and patient's weight and renal function. Consult pediatric-specific guidelines or local protocol. **Hypomagnesemia (example for children):** * **IV:** 25 to 50 mg/kg (0.2 to 0.4 mEq/kg or 0.1 to 0.2 mmol/kg) per dose, not to exceed 2 g (16 mEq or 8 mmol) per dose, infused over 10 to 15 minutes. May be followed by a continuous infusion of 10 to 30 mg/kg/hour (0.08 to 0.24 mEq/kg/hour or 0.04 to 0.12 mmol/kg/hour). **Preeclampsia/Eclampsia (pediatric dosing is not well-established, consult specialist guidelines):** ## Dose Adjustments * **Renal Impairment:** Magnesium is renally excreted. Reduce dose and monitor serum magnesium levels closely in patients with renal impairment. Avoid use if severe renal impairment. ## Contraindications * Hypermagnesemia. * Heart block. * Myocardial infarction. * Hypersensitivity to magnesium sulfate. * Anuria. * Hepatic coma (caution). ## Adverse Effects * **Common:** Flushing, sweating, hypotension, nausea, vomiting, decreased reflexes, drowsiness. * **Serious:** Respiratory depression, cardiac arrhythmias, cardiac arrest, hypothermia, loss of deep tendon reflexes, respiratory paralysis, coma, magnesium toxicity. ## Key Drug Interactions * **Neuromuscular Blocking Agents:** Magnesium sulfate can potentiate the neuromuscular blockade. * **Calcium Channel Blockers:** Additive hypotensive effects and potential for cardiac depression. * **Tetracyclines and Digoxin:** Magnesium may decrease the absorption of oral tetracyclines and digoxin. * **Nifedipine:** Cases of severe hypotension have been reported when nifedipine and magnesium sulfate were co-administered. ## Monitoring * **Serum Magnesium Levels:** Essential for efficacy and safety, especially during continuous infusions and in renal impairment. Target levels vary by indication (e.g., 4 to 7 mEq/L or 2 to 3.5 mmol/L for eclampsia). * **Renal function (BUN, creatinine).** * **Deep tendon reflexes.** * **Respiratory rate and pattern.** * **Blood pressure and heart rate.** * **Urine output.** ## Clinical Pearls * Magnesium sulfate is the drug of choice for treating and preventing seizures in preeclampsia and eclampsia. * Always dilute IV magnesium sulfate before administration. * Rapid IV infusion can cause hypotension and cardiac depression. * Monitor for signs of magnesium toxicity, especially in patients with renal impairment or those receiving high doses. Calcium gluconate is the antidote for magnesium toxicity. * For IM administration, use the ventrogluteal or dorsogluteal muscles and consider the volume to avoid local irritation. *** *This information is intended for clinical use and is not a substitute for professional medical advice. Always consult the most current prescribing information, drug compendia, or local protocols for definitive guidance. Dosing may vary based on patient-specific factors and institutional guidelines.*