Magnesium%2525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is an inorganic salt that acts as an essential mineral and an anticonvulsant. ## Primary Indications * Treatment of hypomagnesemia. * Prevention and treatment of eclampsia and pre-eclampsia. * Management of torsades de pointes. * Treatment of status epilepticus refractory to other agents. ## Adult Dosing * **Hypomagnesemia:** * Mild deficiency: 1 gram (8 mmol) diluted in 100 mL normal saline or D5W infused IV over 5-10 minutes, repeated every 4 hours as needed, or 1 gram (8 mmol) IM every 6 hours for 4 doses. * Severe deficiency: 4-5 grams (32-40 mmol) diluted in 250-1000 mL IV fluid infused over 12-24 hours. Maintenance infusions vary based on serum magnesium levels. * **Eclampsia/Pre-eclampsia (loading dose):** 4-6 grams (32-48 mmol) diluted in 100 mL IV fluid infused over 15-20 minutes. * **Eclampsia/Pre-eclampsia (maintenance dose):** 1-2 grams (8-16 mmol) per hour infused IV. Specific infusion rates may vary by protocol. * **Torsades de Pointes:** 1-2 grams (8-16 mmol) diluted in 10 mL IV fluid infused IV over 5-10 minutes. May be followed by an infusion of 2 grams (16 mmol) per hour. * **Status Epilepticus (refractory):** 2-4 grams (16-32 mmol) diluted in 100-200 mL IV fluid infused IV over 10-15 minutes. Maximum dose is typically dictated by patient response and tolerance, but caution is advised to avoid hypermagnesemia. ## Pediatric Dosing Dosing is highly variable and often based on local protocols and specific indication. * **Hypomagnesemia:** Typically 20-50 mg/kg/dose (elemental magnesium) IV infused over 10-30 minutes, not to exceed 2 grams per dose. May be repeated every 4-12 hours. * **Eclampsia/Pre-eclampsia:** Often follows adult guidelines with appropriate weight-based adjustments for loading and maintenance doses. Consult specific pediatric guidelines for precise dosing. ## Dose Adjustments * **Renal Impairment:** Use with extreme caution. Magnesium is renally excreted. Reduced doses and careful monitoring are necessary. Severe renal impairment may preclude its use. ## Contraindications * Hypermagnesemia. * Heart block (unless a temporary pacemaker is in place). * Myocardial infarction. * Hyperkalemia. * Renal failure (use with caution). ## Adverse Effects * Flushing, sweating, hypotension, nausea, vomiting, decreased deep tendon reflexes, somnolence, muscle weakness, respiratory depression, cardiac arrhythmias, and cardiac arrest. * Hypermagnesemia: Lethargy, hyporeflexia, muscle weakness, difficulty breathing, cardiac arrest. ## Key Drug Interactions * **Neuromuscular Blockers:** Potentiates neuromuscular blockade. * **Calcium Channel Blockers:** Increased risk of hypotension and bradycardia. * **Tetracyclines and Quinolone Antibiotics:** Magnesium can decrease the absorption of these agents. Administer at least 2 hours before or 4-6 hours after magnesium. * **Bisphosphonates:** Magnesium can decrease absorption. Administer at least 2 hours before or 6 hours after magnesium. ## Monitoring * **Serum magnesium levels:** Monitor closely, especially during infusions and in patients with renal impairment. Therapeutic levels for eclampsia are typically 4-7 mEq/L. * **Renal function:** Monitor creatinine and BUN. * **Deep tendon reflexes:** Assess for loss of reflexes, which can indicate toxicity. * **Respiratory rate and effort:** Monitor for signs of respiratory depression. * **Cardiac rhythm:** Monitor for arrhythmias. * **Blood pressure:** Monitor for hypotension. ## Clinical Pearls * Magnesium sulphate should be administered slowly to avoid hypotension and flushing. * Antidote for magnesium toxicity is IV calcium (e.g., calcium gluconate). * In pregnant patients with pre-eclampsia/eclampsia, monitor urine output closely (aim for >30 mL/hr), as reduced output can lead to magnesium accumulation. * Always ensure adequate IV access and resuscitation equipment are readily available. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication.