Magnesium%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is an electrolyte that plays a vital role in numerous biochemical functions, including nerve impulse transmission, muscle contraction, and cardiac function. ## Primary Indications * Treatment of hypomagnesemia. * Prevention and treatment of seizures in preeclampsia and eclampsia. * Management of torsades de pointes. * Status epilepticus refractory to standard therapy. * Bronchodilator in acute severe asthma (adjunctive therapy). ## Adult Dosing * **Hypomagnesemia:** * **Intravenous (IV):** 4-6 grams IV infusion over 1-2 hours, followed by a maintenance infusion of 2-4 grams every 4-12 hours as needed, or 1-2 grams/hour. The total daily dose should generally not exceed 30-40 grams. * **Intramuscular (IM):** 1 gram every 6 hours for 4 doses. * **Preeclampsia/Eclampsia:** * **Loading dose:** 4-6 grams IV infusion over 5-20 minutes. * **Maintenance dose:** 1-2 grams/hour IV infusion. Alternatively, 5 grams IM into each buttock, followed by 5 grams IM in alternating buttocks every 4 hours. * **Torsades de Pointes:** 1-2 grams IV in 10-50 mL dextrose 5% in water (D5W) or normal saline (NS) over 5-10 minutes. May repeat every 5-15 minutes. Follow with an infusion of 0.5-1 gram/hour. * **Status Epilepticus (refractory):** 2-4 grams IV infusion over 10-20 minutes. * **Asthma (adjunctive):** 1-2 grams IV infusion over 15-30 minutes. *Note: Specific dosing protocols, especially for preeclampsia/eclampsia and status epilepticus, may vary by institution.* ## Pediatric Dosing Dosing in pediatric patients is highly variable and depends on the indication, patient weight, and severity of condition. Calculations are often based on elemental magnesium. * **Hypomagnesemia:** Typical doses range from 25-50 mg/kg/dose IV or IM, given over 1-2 hours for IV. Maximum single IV doses are generally 2 grams. * **Status Epilepticus:** 25-100 mg/kg/dose IV, not to exceed 2 grams. *Consult specific pediatric guidelines and institutional protocols for precise dosing.* ## Dose Adjustments * **Renal Impairment:** Magnesium is renally excreted. Reduce dose and monitor serum magnesium levels closely in patients with renal insufficiency. Avoid in severe renal failure unless absolutely necessary and with extreme caution. ## Contraindications * Hypermagnesemia. * Heart block. * Myocardial infarction. * Shock. * Hypermagnesemia. * Intestinal obstruction or perforation (for oral administration). ## Adverse Effects * **Common:** Flushing, warmth, hypotension, nausea, vomiting, diarrhea (especially with oral use). * **Serious:** Respiratory depression, loss of deep tendon reflexes, decreased level of consciousness, cardiac arrhythmias, asystole. Hypermagnesemia can lead to neuromuscular paralysis. ## Key Drug Interactions * **Neuromuscular Blocking Agents:** Magnesium can potentiate neuromuscular blockade, increasing the risk of prolonged paralysis and respiratory depression. * **Calcium Salts:** Concurrent administration can antagonize the effects of magnesium. * **Certain Antibiotics (e.g., tetracyclines, quinolones):** Magnesium can decrease the absorption of oral tetracyclines and quinolones by forming insoluble complexes. Separate administration by at least 2-4 hours. ## Monitoring * **Serum Magnesium Levels:** Monitor frequently, especially during IV infusions, and particularly in patients with renal impairment. Therapeutic levels for hypomagnesemia are typically 1.7-2.2 mmol/L (4-5.5 mg/dL). For eclampsia, levels between 4-7 mmol/L (10-17 mg/dL) are often targeted. * **Renal Function:** Assess baseline and monitor as needed. * **Deep Tendon Reflexes:** Assess for presence and normal response. Diminished reflexes can indicate rising magnesium levels. * **Respiratory Rate and Effort:** Monitor for signs of respiratory depression. * **Cardiac Rhythm:** Monitor ECG, especially if administering rapidly or at high doses. * **Blood Pressure:** Monitor for hypotension. ## Clinical Pearls * Always administer IV magnesium sulphate as a diluted infusion. Rapid IV injection can cause hypotension and cardiac arrest. * IV administration is preferred for rapid correction of severe hypomagnesemia and in emergency situations (e.g., eclampsia, torsades de pointes). * IM administration can cause pain and requires deep injection into large muscle masses. * Oral magnesium salts (e.g., magnesium citrate, oxide) are primarily used as laxatives and are not suitable for treating hypomagnesemia due to poor absorption and gastrointestinal side effects. * Discontinue magnesium sulphate if deep tendon reflexes are absent, respiratory rate is less than 12 breaths/minute, or urine output is inadequate. *** *Disclaimer: This information is intended for clinical professionals and does not replace comprehensive drug information resources. Always consult the current prescribing information and institutional protocols before administering any medication.*