Magnesium Sulfate

Provider Level

RN/Paramedic

Class

Electrolyte, antidysrhythmic, anticonvulsant, tocolytic

Mechanism of Action

Reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholine release at the myoneural junction. Acts as a physiological calcium channel blocker and causes central nervous system depression.

Indications

Torsades de Pointes, seizures associated with eclampsia or severe preeclampsia, severe acute asthma or bronchospasm refractory to standard therapy.

Contraindications

Heart blocks, myocardial damage, hypermagnesemia, myasthenia gravis.

Routes

IV, IO, IM

Onset / Duration

Onset: Immediate for IV/IO and up to 1 hour for IM. Duration: Approx 30 minutes for IV/IO and 3 to 4 hours for IM.

Adverse Effects

Flushing, sweating, hypotension, depressed deep tendon reflexes, flaccid paralysis, respiratory depression, bradycardia, CNS depression, cardiac arrest.

Precautions & Interactions

Use with caution in patients with renal impairment as magnesium is cleared by the kidneys. Concomitant use of other CNS depressants or neuromuscular blockers can exacerbate effects.

Special Considerations

Calcium chloride or calcium gluconate must be readily available as an antidote for magnesium toxicity. Continuous monitoring of blood pressure, respiratory rate, ECG, and deep tendon reflexes is required during administration.