Magnesium%25252525252525252525252525252525252525252520sulphate

# Magnesium Sulphate ## Overview Magnesium sulphate is an electrolyte salt. It is available in oral and intravenous formulations. ## Primary Indications * **Hypomagnesemia:** Treatment of low serum magnesium levels. * **Eclampsia and Pre-eclampsia:** Prevention and treatment of seizures in pregnant women. * **Torsades de Pointes:** Treatment of this specific type of ventricular tachycardia. * **Bronchodilation:** Adjunctive therapy in severe, acute asthma exacerbations. * **Constipation (Oral):** Osmotic laxative. ## Adult Dosing * **Hypomagnesemia (Severe, symptomatic):** * **IV:** 4-6 grams (approx. 32-48 mEq) infused over 5-60 minutes, followed by a continuous infusion of 1-2 grams/hour (approx. 8-16 mEq/hr). Dosage and infusion rate may be adjusted based on serum magnesium levels and clinical response. Maximum infusion rate typically 1 gram/minute to avoid hypotension. * **Eclampsia/Pre-eclampsia:** * **IV Loading Dose:** 4-5 grams (approx. 32-40 mEq) infused over 5 minutes, followed by a maintenance infusion of 1-2 grams/hour (approx. 8-16 mEq/hr) or intermittent intramuscular injections of 5 grams (approx. 40 mEq) every 4 hours. Precise dosing often follows specific hospital protocols. * **Torsades de Pointes:** * **IV:** 1-2 grams (approx. 8-16 mEq) diluted in 100-1000 mL of D5W or normal saline, infused over 5-10 minutes. Further doses may be given as infusions or boluses as needed. * **Bronchodilation (Acute Severe Asthma):** * **IV:** 1-2 grams (approx. 8-16 mEq) diluted in 100 mL normal saline, infused over 15-30 minutes. * **Constipation (Oral):** * **Oral Solution:** 10-30 mL every 4-6 hours as needed. ## Pediatric Dosing * **Hypomagnesemia:** * **IV:** Dosing is highly variable and depends on age, weight, and severity of deficiency. Typical maintenance dose: 20-40 mg/kg/day (approx. 1.6-3.2 mEq/kg/day) divided into 4 doses. Initial correction doses can be higher. Consult specific pediatric guidelines. * **Eclampsia:** * **IV:** Generally similar to adult protocols, but adjusted for weight. Precise dosing often follows specific hospital protocols. * **Torsades de Pointes:** * **IV:** 25-50 mg/kg (approx. 2-4 mEq/kg) as a bolus over 10-20 minutes. May be followed by an infusion. * **Bronchodilation (Acute Severe Asthma):** * **IV:** 25-50 mg/kg (approx. 2-4 mEq/kg) infused over 15-30 minutes. Maximum typically 2 grams. ## Dose Adjustments * **Renal Impairment:** Use with caution. Magnesium is renally excreted. In severe renal impairment, doses should be reduced and serum magnesium levels monitored closely. Oral magnesium can worsen hypermagnesemia in patients with impaired renal function. ## Contraindications * **Hypermagnesemia:** Elevated serum magnesium levels. * **Heart Block:** Second or third-degree heart block (unless a temporary pacemaker is in place). * **Myocardial Infarction:** Use with caution in acute myocardial infarction due to potential for cardiac depression. * **Hypersensitivity:** Known hypersensitivity to magnesium sulphate. * **Anuria:** Oral administration is contraindicated in patients with anuria. ## Adverse Effects * **Most Common (especially with rapid IV infusion or high doses):** Flushing, diaphoresis, hypotension, nausea, vomiting, decreased deep tendon reflexes, lethargy, muscle weakness, respiratory depression, cardiac arrhythmias, and cardiac arrest. * **Oral:** Diarrhea, abdominal cramping. * **Hypermagnesemia:** Symptoms of hypermagnesemia can include drowsiness, confusion, diminished reflexes, muscle weakness, difficulty breathing, irregular heartbeat, and cardiac arrest. ## Key Drug Interactions * **Neuromuscular Blocking Agents:** Magnesium can potentiate the neuromuscular blocking effects of agents like succinylcholine and vecuronium. * **Calcium Channel Blockers:** Increased risk of hypotension and neuromuscular blockade. * **Tetracyclines and Quinolones:** Oral magnesium can decrease the absorption of these antibiotics. Administer 2 hours before or 6 hours after. * **Bisphosphonates:** Oral magnesium can decrease absorption. Separate administration by at least 2 hours. * **Digoxin:** IV magnesium can potentiate digoxin toxicity. ## Monitoring * **Serum Magnesium Levels:** Essential, especially during IV infusions and in patients with renal impairment. * **Renal Function:** Monitor BUN and creatinine. * **Vital Signs:** Blood pressure, heart rate, respiratory rate. * **Deep Tendon Reflexes:** Assess for loss of reflexes, which can indicate hypermagnesemia. * **Urine Output:** Adequate renal function is crucial for magnesium excretion. ## Clinical Pearls * For IV administration, always ensure adequate hydration and renal function. * Rapid IV infusion can cause hypotension and cardiac depression. Infuse slowly as recommended. * Monitor for signs of hypermagnesemia, especially in patients with renal impairment or those receiving prolonged infusions. * Oral magnesium sulphate acts as an osmotic laxative; typically used for short-term relief of constipation. * In eclampsia, magnesium sulphate is the drug of choice to prevent and treat seizures. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and specific institutional protocols before administering any medication. Dosing and guidelines can vary.