Magnesium%252525252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is an electrolyte that plays a vital role in numerous physiological processes, including neuromuscular function, cardiac conduction, and enzyme activity. It is available for intravenous (IV) and intramuscular (IM) administration. ## Primary Indications * Treatment of hypomagnesemia. * Management of eclampsia and pre-eclampsia. * Treatment of severe, persistent asthma (adjunctive therapy). * Management of torsades de pointes. ## Adult Dosing * **Hypomagnesemia:** * **Severe (<0.8 mmol/L or <2 mg/dL):** 4-6 grams IV infused over 5-10 minutes, followed by a continuous infusion of 1-2 grams/hour. Alternatively, 1 gram IM every 4-6 hours for 4-5 doses. * **Moderate (0.8-1.5 mmol/L or 2-3.5 mg/dL):** 2-4 grams IV infused over 5-10 minutes, followed by a maintenance infusion if needed. * **Dosing depends on severity and may vary based on local protocol.** * **Eclampsia/Pre-eclampsia:** Loading dose of 4-6 grams IV infused over 5-20 minutes, followed by a maintenance infusion of 1-2 grams/hour. Alternatively, 5 grams IM into each buttock (10 grams total) with 1 mL 1% procaine added to each vial (if available), followed by 5 grams IM every 4 hours. * **Torsades de Pointes:** 1-2 grams IV in 50-100 mL D5W over 5-10 minutes. Can repeat if needed. * **Severe Asthma (adjunctive):** 1-2 grams IV infused over 15-30 minutes. ## Pediatric Dosing * **Hypomagnesemia:** Dosing is highly variable and depends on the child's weight and serum magnesium levels. Common regimens include IV infusions ranging from 25-100 mg/kg/dose, with maximum doses of 2 grams per dose, often followed by a maintenance infusion. **Specific dosing requires consultation with pediatric critical care or pharmacy protocols.** * **Eclampsia:** Generally not recommended in pediatric patients. * **Asthma:** 25-75 mg/kg IV infused over 15-30 minutes, with a maximum dose of 2 grams. ## Dose Adjustments * **Renal Impairment:** Magnesium sulphate is renally excreted. Use with caution in patients with renal impairment. Dose reduction and careful monitoring of serum magnesium levels are necessary. Avoid in severe renal failure if possible. ## Contraindications * Hypermagnesemia. * Heart block. * Myocardial infarction with impending heart failure. * Renal failure (use with extreme caution or avoid). ## Adverse Effects * **Common:** Flushing, warmth, diaphoresis, hypotension, nausea, vomiting, decreased deep tendon reflexes, lethargy. * **Serious:** Respiratory depression, cardiac arrhythmias, cardiac arrest, loss of deep tendon reflexes, absent respirations, coma. ## Key Drug Interactions * **Calcium Salts:** Can antagonize the cardiac and neuromuscular effects of magnesium. * **Neuromuscular Blocking Agents:** Magnesium can potentiate neuromuscular blockade, increasing the risk of respiratory depression. * **Nifedipine:** Concomitant use in pre-term labor may increase the risk of maternal hypotension. * **Tetracyclines and Bisphosphonates:** Oral absorption may be decreased due to reduced gastrointestinal motility. ## Monitoring * **Serum Magnesium Levels:** Monitor frequently, especially during loading doses and continuous infusions. Target levels vary by indication (e.g., 2-3.5 mmol/L or 4-7 mg/dL for eclampsia). * **Renal Function:** Monitor creatinine and BUN. * **Deep Tendon Reflexes:** Assess for presence and grade. Loss of reflexes indicates toxicity. * **Respiratory Rate and Depth:** Monitor for signs of respiratory depression. * **Blood Pressure:** Monitor for hypotension. * **Urine Output:** Essential for assessing renal function and magnesium excretion. * **ECG:** Monitor for changes in cardiac rhythm, especially in patients receiving high doses or with underlying cardiac conditions. ## Clinical Pearls * Magnesium sulphate is hypertonic; infuse IV doses slowly to avoid pain and phlebitis. * IM injections can be painful and should be administered deep into a large muscle mass, potentially with procaine if available. * Magnesium toxicity is directly related to serum levels and renal function. The presence of deep tendon reflexes is a key indicator of adequate magnesium levels. * In cases of magnesium toxicity, discontinue magnesium infusion and administer IV calcium gluconate or calcium chloride. *** *Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication.*