Magnesium%25252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulfate is an essential mineral that plays a crucial role in numerous biochemical functions. It is available in injectable and oral formulations. ## Primary Indications * Treatment of hypomagnesemia. * Management of eclampsia and pre-eclampsia. * Treatment of torsades de pointes. * Adjunct in management of status asthmaticus. * Adjunct in management of severe hypokalemia. ## Adult Dosing * **Hypomagnesemia:** * Severe: 4-6 g IV as a loading dose, followed by 2-4 g IV infused over 4-6 hours, or 1 g IM every 6 hours for 4 doses. Dosing is often guided by serum magnesium levels and renal function. * Mild/Moderate: 1 g IV infused over 5-60 minutes, or 1 g IM every 6 hours for 4 doses. * **Eclampsia/Pre-eclampsia:** 4-6 g IV loading dose, followed by a maintenance infusion of 1-2 g/hour. Alternate IM regimens exist (e.g., 5 g IM in each buttock initially, followed by 5 g IM every 4 hours). Dosing specific to local protocols for seizure prophylaxis and treatment. * **Torsades de Pointes:** 1-2 g IV in 10-100 mL D5W over 5-60 minutes. May repeat if necessary. Further doses may be given as a continuous infusion (e.g., 0.5-1 g/hour). * **Status Asthmaticus:** 1.2-2 g IV infused over 15-30 minutes. * **Severe Hypokalemia:** 3-4 g IV added to intravenous fluids. ## Pediatric Dosing * **Hypomagnesemia:** Dosing is highly variable and often guided by local protocols and serum magnesium levels. Typical doses range from 25-50 mg/kg/dose IV or IM, not to exceed 2 g per dose. * **Eclampsia:** 40 mg/kg IV loading dose (max 4 g), followed by 5-10 mg/kg/hour infusion (max 500 mg/hour). Dosing specific to local protocols. * **Status Asthmaticus:** 25-50 mg/kg IV infused over 15-30 minutes, maximum dose 2 g. ## Dose Adjustments * **Renal Impairment:** Magnesium is renally excreted. Caution and dose reduction are necessary in patients with impaired renal function. Monitor serum magnesium levels closely. Avoid in severe renal impairment if possible. ## Contraindications * Hypermagnesemia. * Heart block. * Myocardial infarction with myocardial damage. * Hyperkalemia (when used as a potential treatment adjunct). * Shock. * Intestinal obstruction. * Anuria. ## Adverse Effects * **Common:** Flushing, sweating, nausea, vomiting, decreased deep tendon reflexes, hypotension, respiratory depression. * **Serious:** Cardiac arrest, bradycardia, altered mental status, muscle weakness, hypermagnesemia (symptoms include hyporeflexia, hypotension, respiratory depression, cardiac arrhythmias). ## Key Drug Interactions * **Neuromuscular Blockers:** Magnesium can potentiate neuromuscular blockade, potentially leading to prolonged muscle weakness and respiratory depression. * **Calcium:** IV calcium may be used as an antagonist in severe hypermagnesemia. * **Tetracyclines and Quinolones:** Oral magnesium sulfate can decrease the absorption of these antibiotics. Administer at least 2-3 hours apart. * **Bisphosphonates:** Oral magnesium sulfate can decrease the absorption of bisphosphonates. Administer at least 2 hours before or 6-8 hours after bisphosphonate. * **Digoxin:** High doses of IV magnesium can cause cardiotoxicity in patients taking digoxin. ## Monitoring * Serum magnesium levels (especially with prolonged therapy, renal impairment, or significant doses). * Renal function (BUN, creatinine). * Deep tendon reflexes. * Respiratory rate and effort. * Blood pressure. * Urine output. * ECG for evidence of cardiotoxicity or hyperkalemia effects. ## Clinical Pearls * Injectable magnesium sulfate is a high-alert medication. Double-check doses and infusion rates. * Rapid IV administration can cause hypotension and cardiac arrhythmias. Infuse as recommended. * The therapeutic range for serum magnesium is typically 1.7-2.6 mg/dL (0.7-1.05 mmol/L), but may be higher in eclampsia management. * Calcium gluconate or calcium chloride is the antidote for severe magnesium toxicity. * Oral magnesium sulfate preparations can cause diarrhea. *** ***Disclaimer:** This information is intended for healthcare professionals. Always consult the most current official prescribing information and relevant clinical guidelines before making any treatment decisions. Dosing and indications may vary based on patient-specific factors and local institutional protocols.*