Magnesium Sulfate

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Magnesium sulfate
Class/ MOA

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Class
Electrolyte
Mechanism of Action
Reduces striated muscle contractions and blocks peripheral neuromuscular transmission
by reducing acetylcholinesterase release at the myoneural junction; manages seizures
in toxemia of pregnancy; induces uterine relaxation; can cause bronchodilation after
beta-agonists and anticholinergics have been used.

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Magnesium sulfate
I/CI

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Indications
Seizures of eclampsia (Toxemia of pregnancy).
Torsades de Pointes.
Hypomagnesemia.
TCA overdose-induced dysrhythmias.
Digitalis-induced dysrhythmias.
Class IIa agent for refractory VF and VT after administration of Lidocaine doses.
Contraindications
Heart blocks.
Renal diseases

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Magnesium sulfate
DI/AR

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Adverse Reactions
Respiratory and CNS depression.
Hypotension, cardiac arrest and asystole may occur.
Facial flushing, diaphoresis, depressed reflexes.
Circulatory collapse.
Drug Interactions
May enhance effects of other CNS depressants.
Serious changes in overall cardiac function may occur with cardiac glycosides.

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Magnesium sulfate
how supplied

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How Supplied
2 ml and 20 ml vials of a 50% solution.

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Magnesium sulfate
doses

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Dosage and Administration
Adult: Seizure activity associated with pregnancy: 1-4 gm IV over 10 minutes.
For Torsades de Pointes or Refractory VF/VT: 1-2 grams IV over 1-2 minutes.
Pediatric: Asthma/bronchospasm, severe: 25 mg./kg. over 10 minutes IV.
Usually mixed in 50-100 CC of NS to be given IV.

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Magnesium sulfate
DOA/ specials

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Duration of Action
Onset: Immediate.
Peak effect: variable.
Duration: 3-4 hours.
Special Considerations
Pregnancy safety: Recommended that drug not be given in the 2 hours before delivery,
if possible.
IV calcium gluconate or calcium chloride should be available as antagonist if needed.
Use with caution in patients with renal failure.
Magnesium sulfate is being used for acute MI patients in some systems under Medical
Direction.