Magnesium%2525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulfate is an electrolyte and mineral supplement. It is a naturally occurring inorganic salt. ## Primary Indications * Treatment of hypomagnesemia. * Management of seizures in severe preeclampsia and eclampsia. * Treatment of torsades de pointes. * Adjunctive therapy for bronchospasm in acute severe asthma. ## Adult Dosing * **Hypomagnesemia:** * Severe: 4 grams IV initially, followed by 1-2 grams IV every 4-6 hours as needed, or infused at 1 gram/hour. Maintenance dose may be needed based on serum magnesium levels. * Less severe: 1 gram IV or IM every 6 hours for 4 doses. * **Preeclampsia/Eclampsia:** 4-6 grams IV loading dose, followed by 1-2 grams/hour continuous infusion. Alternatively, 5 grams IM in each buttock for the loading dose, followed by 5 grams IM every 4 hours. * **Torsades de Pointes:** 1-2 grams IV in 10-50 mL dextrose 5% in water or normal saline over 10-20 minutes. May repeat, followed by a continuous infusion of 0.5-1 gram/hour if needed. * **Asthma (Adjunctive):** 1-2 grams IV in 50-100 mL normal saline or dextrose 5% in water over 15-30 minutes. Dosing may depend on local protocol and patient response. ## Pediatric Dosing * **Hypomagnesemia:** 25-50 mg/kg/dose IV or IM every 4-6 hours for 4 doses. Maximum single dose 2 grams. * **Eclampsia:** 40 mg/kg IV loading dose over 5-10 minutes, followed by 20 mg/kg/hour continuous infusion. Maximum loading dose 4 grams. Dosing for pediatric patients is often guided by institutional protocols. ## Dose Adjustments No specific dose adjustment is required for renal impairment due to the risk of accumulation. However, caution is advised, and monitoring of serum magnesium and renal function is crucial. In severe renal impairment, the dose should be significantly reduced, and infusion rates may need to be slowed. ## Contraindications * Hypermagnesemia. * Heart block (second or third degree) unless a pacemaker is present. * Myocardial infarction. * Shock. * Severe renal impairment. ## Adverse Effects * **Common:** Flushing, sweating, hypotension, nausea, vomiting, drowsiness, decreased reflexes. * **Serious:** Respiratory depression, cardiac arrhythmias, cardiac arrest, hypothermia, muscle weakness, loss of deep tendon reflexes. ## Key Drug Interactions * **Neuromuscular Blocking Agents:** Magnesium sulfate can potentiate neuromuscular blockade, increasing the risk of prolonged respiratory depression. * **Calcium Channel Blockers:** Additive hypotensive effects. * **Tetracyclines and Quinolones:** Magnesium sulfate can decrease the absorption of these antibiotics. Administer at least 2-3 hours before or 4-6 hours after magnesium sulfate. * **Bisphosphonates:** Magnesium sulfate may decrease the absorption of bisphosphonates. Administer at least 2 hours before magnesium sulfate. ## Monitoring * Serum magnesium levels (prior to and during therapy, especially with IV infusions). * Deep tendon reflexes. * Respiratory rate and depth. * Blood pressure. * Urine output. * Renal function (creatinine, BUN). * Cardiac rhythm (especially with high doses or prolonged infusions). ## Clinical Pearls * Magnesium is a CNS depressant and vasodilator. * Loss of deep tendon reflexes typically precedes respiratory depression and cardiac arrest. If reflexes are absent, discontinue magnesium sulfate immediately. * Monitor for hypermagnesemia, especially in patients with renal impairment. Symptoms include nausea, vomiting, flushing, lethargy, and hypotension. * When used for preeclampsia/eclampsia, administer with caution and monitor for signs of magnesium toxicity. *** *Please verify current prescribing information for definitive guidance. This information is for educational purposes only and does not substitute professional medical advice.*