Please check your internet connection and try again.
# Magnesium Sulphate
## Overview
Magnesium sulfate is an essential mineral that plays a crucial role in numerous biochemical functions, including neuromuscular transmission and muscle contraction. It is available in parenteral and oral formulations.
## Primary Indications
* **Hypomagnesemia:** Treatment of magnesium deficiency.
* **Eclampsia/Preeclampsia:** Prevention and treatment of seizures associated with severe preeclampsia and eclampsia.
* **Torsades de Pointes:** Treatment of polymorphic ventricular tachycardia, especially when associated with a prolonged QT interval.
* **Bronchodilation:** Adjunctive therapy for severe, refractory bronchospasm in asthma.
* **Constipation (Oral):** Osmotic laxative.
## Adult Dosing
* **Hypomagnesemia:**
* **Severe deficiency:** 4-6 g IV infusion over 10-20 minutes, followed by 1-2 g/hour by continuous infusion. Titrate to serum magnesium levels.
* **Less severe deficiency:** 1-2 g IM or IV in divided doses over 1-2 hours.
* **Eclampsia/Preeclampsia:**
* **Loading dose:** 4-6 g IV infusion over 5-10 minutes.
* **Maintenance dose:** 1-2 g/hour by continuous infusion. Adjust based on clinical response and serum magnesium levels.
* **Torsades de Pointes:** 1-2 g IV in 10-20 mL of D5W over 5-10 minutes. May repeat. Follow with 0.5-1 g/hour infusion if needed.
* **Bronchodilation:** 1-2 g IV infusion over 15-30 minutes.
* **Constipation (Oral):** 2-4 tablespoons (approximately 30 mL per tablespoon) of a 10-15% solution PO every 4-6 hours as needed.
*Note: Dosing for hypomagnesemia and eclampsia/preeclampsia may vary based on local protocol and patient response.*
## Pediatric Dosing
* **Hypomagnesemia:**
* **Severe:** 50-100 mg/kg/dose (0.2-0.4 mmol/kg/dose) IV infusion over 10-20 minutes. Maximum dose: 2 g. Follow with 20-30 mg/kg/dose (0.1-0.12 mmol/kg/dose) every 4-6 hours as needed.
* **Less severe:** 50 mg/kg/dose (0.2 mmol/kg/dose) IV or IM in divided doses over 1-2 hours.
* **Eclampsia (off-label):** Similar to adult loading and maintenance doses, adjusted by weight if necessary. Consult pediatric critical care protocols.
* **Torsades de Pointes:** 25-50 mg/kg/dose (0.1-0.2 mmol/kg/dose) IV infused over 10-20 minutes. Maximum dose: 2 g.
*Note: Pediatric dosing for magnesium sulfate is not as well-established as adult dosing and should be guided by expert consultation or specific institutional protocols.*
## Dose Adjustments
* **Renal Impairment:** Reduce dose significantly in patients with impaired renal function. Monitor serum magnesium levels closely. In severe renal impairment, it may be necessary to withhold magnesium.
## Contraindications
* Myocardial damage
* Heart block
* Hypermagnesemia
* Hypercalcemia
* Anuria
* Bowel obstruction (for oral formulation)
## Adverse Effects
* **Common:** Flushing, diaphoresis, hypotension, nausea, vomiting, decreased reflexes, lethargy, drowsiness.
* **Serious:** Respiratory depression, cardiac arrest, hypermagnesemia (muscle weakness, absent deep tendon reflexes, ECG changes, hypotension, respiratory arrest, cardiac arrest).
## Key Drug Interactions
* **Neuromuscular blocking agents:** May potentiate neuromuscular blockade.
* **Calcium channel blockers:** Increased risk of hypotension and heart block.
* **Digoxin:** Risk of hypotension and arrhythmias.
* **Tetracyclines and Quinolone antibiotics:** May decrease absorption of these antibiotics. Separate administration by at least 2-3 hours.
## Monitoring
* **Serum magnesium levels:** Especially important in patients with renal impairment and those receiving continuous infusions. Therapeutic levels for hypomagnesemia are typically 1.7-2.2 mmol/L (4-5.5 mg/dL). Therapeutic levels for eclampsia are generally 4-8 mEq/L (2-4 mmol/L).
* **Renal function (BUN, creatinine)**
* **Deep tendon reflexes:** Assess for signs of hypermagnesemia.
* **Respiratory rate:** Monitor for signs of respiratory depression.
* **Blood pressure and heart rate:** Monitor for hypotension and arrhythmias.
* **Urine output:** Essential for assessing renal function and fluid balance.
## Clinical Pearls
* When administering IV magnesium sulfate, ensure continuous cardiac monitoring and have resuscitation equipment readily available.
* Rapid IV administration can cause hypotension, flushing, and cardiac arrhythmias. Administer infusions slowly and as prescribed.
* Magnesium sulfate is incompatible with many IV solutions; check compatibility before co-administration. Dilute for IV infusion as recommended.
* For IM administration, use large muscle masses and avoid administering more than 5 mL in one site due to potential for irritation.
* Oral magnesium sulfate can cause diarrhea and abdominal cramping.
***
*Disclaimer: This information is intended for healthcare professionals. Always consult the official prescribing information and institutional protocols for the most current and comprehensive guidance before making any clinical decisions.*
