Magnesium%252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulfate is an essential mineral that plays a crucial role in numerous physiological processes, including neuromuscular transmission and cardiac excitability. It is available for intravenous (IV) and intramuscular (IM) administration. ## Primary Indications * Treatment of hypomagnesemia. * Management of severe preeclampsia and eclampsia. * Treatment of torsades de pointes. * Off-label: Status epilepticus refractory to other agents, severe asthma exacerbations. ## Adult Dosing * **Hypomagnesemia:** * Severe deficiency: 4-6 g IV administered as an infusion over 15-60 minutes, followed by 2-4 g IV every 4-12 hours as needed. * Moderate deficiency: 2-4 g IM, divided into two doses and given in alternate buttocks. * Maintenance: 1-2 g IV infusion every 12 hours, or 1 g IM every 6 hours. * **Preeclampsia/Eclampsia Prophylaxis and Treatment:** * Loading dose: 4-6 g IV infused over 5-10 minutes. * Maintenance infusion: 1-2 g/hour IV. * IM: 5 g IM in alternate buttocks every 4 hours if IV access is unavailable. * **Torsades de Pointes:** 1-2 g IV in 10 mL of D5W infused rapidly over 5-10 minutes. May repeat. Further infusions at 1 g/hour IV. * **Status Epilepticus (Refractory):** Dosing varies significantly; consult local protocol. Often involves initial boluses followed by infusions. ## Pediatric Dosing Dosing in pediatrics is highly variable and depends on the indication and patient weight. Consult specific pediatric guidelines or local protocols. * **Hypomagnesemia:** Typical doses range from 25-50 mg/kg/dose IV or IM, not to exceed 2 g/dose. Infusions usually over 30-60 minutes. * **Eclampsia:** Dosing is complex and often follows adult regimens adapted for weight. ## Dose Adjustments * **Renal Impairment:** Magnesium is renally excreted. Use with caution in patients with impaired renal function. Reduce dose and monitor serum magnesium levels closely. Doses should be reduced in moderate to severe renal impairment. ## Contraindications * Myocardial damage. * Heart block. * Hypermagnesemia. * Hyperkalemia (relative contraindication). * Hypocalcemia (may be exacerbated). ## Adverse Effects * **Common:** Flushing, warmth, hypotension, sweating, nausea, vomiting. * **Serious:** Respiratory depression, cardiac arrhythmias, cardiac arrest, loss of deep tendon reflexes, central nervous system depression, hypermagnesemia (especially with renal impairment). ## Key Drug Interactions * **Neuromuscular Blockers:** Magnesium can potentiate the neuromuscular blockade, increasing the risk of prolonged paralysis. * **Calcium Channel Blockers:** Additive hypotensive effects. * **Potassium-Sparing Diuretics:** Increased risk of hyperkalemia. * **Tetracyclines and Fluoroquinolones:** Magnesium can decrease the absorption of these antibiotics; administer at least 2 hours apart. ## Monitoring * **Serum Magnesium Levels:** Monitor regularly, especially in patients with renal impairment, and after dose adjustments. Therapeutic range for hypomagnesemia treatment is typically 4-7 mg/dL (2-3.5 mmol/L). Toxicity may be seen above 7 mg/dL (3.5 mmol/L). * **Renal Function:** Assess baseline and monitor as needed. * **Deep Tendon Reflexes:** Monitor for loss of reflexes, an early sign of hypermagnesemia. * **Respiratory Rate and Blood Pressure:** Monitor for signs of respiratory depression and hypotension. * **Cardiac Rhythm:** Especially important in torsades de pointes treatment and with high doses. ## Clinical Pearls * Always dilute IV magnesium sulfate before rapid infusion to reduce the risk of hypotension and flushing. * Magnesium sulfate is a CNS depressant; monitor for somnolence and respiratory status. * For IM administration, a 50% solution (500 mg/mL) is commonly used. Divide large IM doses into two separate injections to reduce pain and induration. * Hypocalcemia can occur with severe hypomagnesemia and may require calcium replacement. Correct magnesium deficiency first before treating hypocalcemia if both are present. **Disclaimer:** This information is for educational purposes only and does not substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions.