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Magnesium Sulfate

Classification

Electrolyte

Indications

ACP: Treatment of Torsades de Pointes

ACP: Bronchospasm refractory to bronchodilation in acute asthma exacerbation

ACP: Management of seizures in pregnancy associated with hypertension

Contraindications

Contraindication

Hypersensitivity to magnesium sulfate
Second or third-degree AV block

Caution

Hypersensitivity to magnesium sulfate
Second or third-degree AV block
Hypotension
Concurrent use of neuromuscular blockade
Myasthensia gravis

Adult dosages

ACP: Torsades de Pointes/Polymorphic VT Refer to WCT

For perfusing rhythms (stable): 2 g IV over 15 minutes

In cardiac arrest: 2 g IV push over 1-2 minutes

ACP: Bronchospasm refractory to bronchodilation

2 g IV over 15 minutes

ACP: Prevention of recurrent seizures in pregnancy associated with hypertension Refer to Eclampsia

Cardiac monitoring is required
Administer 5 g intravenously over 15 minutes followed by 1 g/hour
Can give 5 g intramuscularly if unable to start IV (use bilateral buttocks) followed by 5 g IM every 4 hours

If seizures persist greater than 5 minutes contact EPOS for further care options.

Pediatric Considerations And Dosing

Follow weight-based dosing

ACP: Torsades de Pointes/polymorphic VT

For perfusing rhythms(stable): 50 mg/kg IV/IO (maximm 2 g) over 15 minutes
In cardiac arrest 50 mg/kg IV/IO (maximum 2 g) IV push over 1-2 minutes

ACP: Bronchospasm

Severe asthma refractory to bronchodilator: 50 mg/kg IV/IO (maximum 2 g) over 15 minutes

Mechanism Of Action

The precise mechanism of action of magnesium sulfate is not entirely clear. It appears to alter membrane potential, slowing conduction and relaxing smooth muscle.

Pharmacokinetics

Intravenous:

Onset: 1-2 minutes
Peak: < 5 minutes
Duration: 30 minutes as anticonvulsant

Infusions may take up to 20-30 minutes to produce significant bronchodilation

Adverse Effects

Hypotension
Heart block
Drowsiness
Respiratory depression
Arrhythmias

Overdose

Calcium chloride should be available for magnesium sulphate overdose.

Warning And Precautions

May prolong the effects of non-depolarizing neuromuscular blockers and may potentiate the effects of calcium channel blockers.