Home Drug Guide Magnesium Sulfate

Drug Guide

Generic Name

Magnesium Sulfate

Brand Names Epsom Salt, Mag sulfate

Classification

Therapeutic: Electrolyte replenisher, anticonvulsant

Pharmacological: Magnesium salt

FDA Approved Indications

Treatment of magnesium deficiency
Prevention and control of seizure in eclampsia
Tocolytic agent to delay preterm labor in certain cases

Mechanism of Action

Magnesium sulfate replaces magnesium in the body, acting as a calcium antagonist, reducing acetylcholine release at neuromuscular junctions, leading to decreased neuromuscular transmission, CNS depression, and vasodilation.

Dosage and Administration

Adult: Varies by indication; for eclampsia, IV loading dose of 4-6 g over 15-20 minutes, then maintenance infusion of 1-2 g/hr.

Pediatric: Dose varies; typically 25-50 mg/kg IV over 20 minutes for magnesium deficiency or preeclampsia management.

Geriatric: Adjust dose based on renal function and clinical response.

Renal Impairment: Use with caution; magnesium clearance is reduced, risk of toxicity.

Hepatic Impairment: No specific dosage adjustments; monitor closely.

Pharmacokinetics

Absorption: Well absorbed when administered parenterally.

Distribution: Widely distributed in total body water.

Metabolism: Not significantly metabolized.

Excretion: Primarily via kidneys.

Half Life: 4.7 hours in individuals with normal renal function.

Contraindications

Renal failure
Heart block
Active myocardial infarction

Precautions

Monitor blood magnesium levels during therapy
Use with caution in neuromuscular disorders
Assess deep tendon reflexes regularly

Adverse Reactions - Common

Flushing (Common)
Sedation (Common)
Muscle weakness (Common)

Adverse Reactions - Serious

Respiratory depression (Serious)
Cardiac arrest (Serious)
Hypocalcemia (Serious)

Drug-Drug Interactions

Additive effects with other CNS depressants
Potential for hypermagnesemia with nephrotoxic drugs

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor deep tendon reflexes, respiratory rate, serum magnesium levels, and renal function.

Diagnoses:

Risk for ineffective airway clearance
Risk for electrolyte imbalance

Implementation: Administer IV infusion as ordered, monitor patient responses, ensure proper infusion rate.

Evaluation: Check for signs of toxicity, verify serum magnesium levels, and assess for therapeutic response.

Patient/Family Teaching

Report any weakness, difficulty breathing, or irregular heartbeat.
Avoid other CNS depressants unless advised by a healthcare provider.
Follow dosing instructions carefully.

Special Considerations

Black Box Warnings:

Potential for respiratory depression and cardiac arrest with rapid IV administration.

Genetic Factors: None established.

Lab Test Interference: May interfere with magnesium tests; interpret lab results cautiously.

Overdose Management

Signs/Symptoms: Hypermagnesemia symptoms include flushing, hypotension, respiratory depression, muscle weakness, loss of deep tendon reflexes, cardiac arrest.

Treatment: Discontinue magnesium infusion, administer calcium gluconate IV as antidote, support airway and ventilation, monitor cardiac status.

Storage and Handling

Storage: Store at room temperature away from moisture.

Stability: Stable for 24 months when properly stored.