Magnesium%25252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is an electrolyte that plays a role in neuromuscular transmission and muscle contraction. It is available for intravenous (IV) and intramuscular (IM) administration. ## Primary Indications * Treatment of hypomagnesemia. * Prevention and treatment of seizures in preeclampsia and eclampsia. * Management of status epilepticus refractory to first-line agents. * Treatment of torsades de pointes. * Management of severe asthma exacerbations (adjunctive therapy). ## Adult Dosing * **Hypomagnesemia:** * **Acute Symptomatic (e.g., seizures, arrhythmias):** 4-6 grams IV bolus, followed by a continuous infusion of 1-2 grams per hour. Maximum infusion rate typically 2 grams per hour. Some protocols may use up to 10 grams as a loading dose. * **Asymptomatic:** 1-6 grams IM or IV every 6-12 hours for 3-5 days. * **Preeclampsia/Eclampsia Prophylaxis:** 4-6 grams IV loading dose over 5-20 minutes, followed by a continuous infusion of 1-2 grams per hour. * **Eclamptic Seizures (Treatment):** 4-6 grams IV bolus, followed by a continuous infusion of 1-2 grams per hour. If seizures recur, may administer additional 2-4 gram IV bolus. * **Status Epilepticus (Adjunctive):** 1-2 grams IV infused over 1-2 minutes. * **Torsades de Pointes:** 1-2 grams IV as a bolus, may repeat. Followed by infusion of 2-4 grams over 1 hour, then maintenance infusion of 0.5-1 gram per hour. * **Severe Asthma:** 1-2 grams IV infused over 15-20 minutes. Dosing for specific indications can vary significantly based on institutional protocols. ## Pediatric Dosing * **Hypomagnesemia:** * **Acute Symptomatic:** 25-50 mg/kg IV bolus over 5-10 minutes, not to exceed 2 grams. May follow with an infusion of 50-100 mg/kg/day divided every 6-8 hours. * **Asymptomatic:** 50 mg/kg IM or IV every 6-12 hours for 3-5 days. * **Status Epilepticus (Adjunctive):** 25-50 mg/kg IV infused over 10-20 minutes, not to exceed 2 grams. * **Preeclampsia/Eclampsia Prophylaxis/Treatment:** Dosing is generally similar to adults in adolescents. Specific pediatric guidelines are less established for this indication. * **Torsades de Pointes:** 25-50 mg/kg IV bolus, may repeat. Followed by infusion. Extrapolation of adult data to pediatric populations requires careful consideration. Consult pediatric-specific guidelines. ## Dose Adjustments No dose adjustment is typically required for hepatic impairment. Reduce dose and monitor closely in patients with renal impairment. ## Contraindications * Heart block greater than first degree. * Myocardial infarction. * Hypermagnesemia. * Hypocalcemia (use with caution). * Bowel obstruction or perforation (for oral administration, not relevant for IV/IM). ## Adverse Effects Common: Flushing, sweating, hypotension, nausea, vomiting, hyporeflexia. Serious: Respiratory depression, cardiac arrhythmias, cardiac arrest, hypermagnesemia, hypocalcemia. ## Key Drug Interactions * **Neuromuscular Blockers:** Potentiates neuromuscular blockade, increasing risk of prolonged respiratory depression. * **Calcium Salts:** May antagonize the cardiac effects of magnesium. * **Nifedipine:** May increase risk of hypotension and profound muscle weakness. * **Digoxin:** Increased risk of digoxin toxicity if hypomagnesemia is corrected too rapidly with magnesium. ## Monitoring * **Magnesium Levels:** Serum magnesium levels should be monitored, especially with prolonged infusions or in renal impairment. Target levels vary by indication. * **Renal Function:** Monitor creatinine and BUN. * **Deep Tendon Reflexes:** Loss of reflexes indicates magnesium toxicity. * **Respiratory Rate and Effort:** Monitor for signs of respiratory depression. * **Blood Pressure and Heart Rate:** Monitor for hypotension and arrhythmias. * **Urine Output:** Monitor for adequate renal excretion. ## Clinical Pearls * Administer IV magnesium slowly to minimize hypotension and flushing. * IV calcium (e.g., calcium gluconate) should be readily available as an antidote for severe toxicity. * In preeclampsia/eclampsia, continuous monitoring of reflexes, respiratory rate, and urine output is crucial. * Intramuscular injections can be painful and should be administered deep into a large muscle mass, often with procaine to reduce pain. Divide large IM doses between two sites. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication. This information is not a substitute for professional medical judgment.