Magnesium%2525252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is an inorganic salt that acts as a central nervous system depressant and a smooth muscle relaxant. It is available for intravenous and intramuscular administration. ## Primary Indications * Treatment of hypomagnesemia. * Management of eclampsia and pre-eclampsia. * Management of torsades de pointes. * Adjunctive treatment in severe asthma exacerbations (primarily inhaled). ## Adult Dosing * **Hypomagnesemia:** * Intramuscular: 1 gram every 6 hours for 4 doses (total 4 grams). * Intravenous: 1 to 4 grams as a single dose, may be repeated if necessary. * **Eclampsia/Pre-eclampsia:** * Loading Dose: 4 to 6 grams administered intravenously over 5 to 20 minutes. * Maintenance Dose: 1 to 2 grams per hour by continuous intravenous infusion. Dosing may vary based on local protocol and patient response. * **Torsades de Pointes:** * 2 grams diluted in 10 mL of D5W administered intravenously over 1 minute, followed by an infusion of 1 gram per hour if needed. * **Severe Asthma Exacerbations (Adjunctive):** * 1 to 2 grams diluted in 100 mL of saline administered intravenously over 15 to 30 minutes. ## Pediatric Dosing * **Hypomagnesemia:** * Intravenous: 25 to 50 mg/kg per dose every 4 to 6 hours for 3 to 4 doses. Maximum dose: 2 grams per dose. * Intramuscular: 20 to 50 mg/kg per dose every 4 to 6 hours. Maximum dose: 2 grams per dose. * **Eclampsia/Pre-eclampsia:** Dosing in pediatric patients with pre-eclampsia/eclampsia is not well established and should follow expert consultation or institutional guidelines. * **Torsades de Pointes:** 25 to 50 mg/kg per dose intravenously, maximum 2 grams. ## Dose Adjustments No specific dose adjustments are typically required for hepatic impairment. Caution is advised in renal impairment; doses may need to be reduced and serum magnesium levels monitored closely. ## Contraindications * Hypermagnesemia. * Heart block. * Myocardial infarction. * Myasthenia gravis (relative contraindication, use with caution). ## Adverse Effects Common: Flushing, sweating, hypotension, somnolence, decreased reflexes, nausea, vomiting. Serious: Respiratory depression, cardiac arrest, hypermagnesemia, hypocalcemia, hypothermia. ## Key Drug Interactions * **Neuromuscular Blockers:** Magnesium sulphate can potentiate the effects of neuromuscular blocking agents, leading to prolonged neuromuscular blockade. * **Calcium Channel Blockers:** Additive hypotensive effects. * **Potassium-Sparing Diuretics:** Increased risk of hypermagnesemia. * **Tetracyclines and Quinolones:** Magnesium sulphate may decrease the absorption of these antibiotics; administer at least 2 hours before or 4-6 hours after magnesium sulphate. ## Monitoring * **Serum Magnesium Levels:** Monitor at baseline and regularly during therapy, especially in patients with renal impairment or receiving prolonged treatment. Therapeutic range is typically 1.7 to 2.2 mmol/L (4 to 5.5 mg/dL). * **Renal Function:** Monitor urine output and serum creatinine. * **Vital Signs:** Blood pressure, heart rate, respiratory rate. * **Neurological Status:** Deep tendon reflexes, level of consciousness. * **ECG:** Especially in patients with cardiac conditions or receiving high doses. ## Clinical Pearls * Magnesium sulphate should be administered slowly to avoid hypotension. * Monitor for signs of magnesium toxicity, including absent deep tendon reflexes, hypotension, somnolence, and respiratory depression. * Ensure adequate calcium is available to treat potential hypermagnesemia. * In eclampsia, continue magnesium sulphate for at least 24 hours after delivery or seizure, whichever is longer. *** **Disclaimer:** This information is intended for clinical use and does not replace professional medical judgment. Always consult the most current prescribing information or a qualified healthcare provider for definitive guidance.