Magnesium Sulfate
Class:
Electrolyte.
Electrolyte.
Mechanism of Action:
Reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholinestrase 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.
Reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholinestrase 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.
Indications:
- Acute Asthma / Bronchospasm.
- Seizures of eclampisa (Toxemia of pregnancy).
- Torsades de Pointes.
- Hypomagnesemia.
- TCA overdose-induced dysrhythmias.
- Digitalis-induced dysrhytmias.
Contraindications:
- Heart blocks.
- Renal disease.
Adverse reactions:
- Respiratory or CNS depression.
- Hypotension, cardiac arrest and asystole may occur.
- Facial flushing, diaphoresis, depressed reflexes.
- Circulatory collapse.
- Blood pressure decrease. ↓
- Urine output decrease. ↓
- Respiratory rate decrase. ↓
- Patellar reflex absent. ↓
Drug Interactions
- May enhance effects of other CNS depressants.
- Serious changes in overall cardiac function may occur with cardiac glycosides.
Adult Dosage and Administration
- Seizures of eclampsia: 2-4 gm IV over 5 minutes.
- Torsades de Pointes, Refractory VF/VT: 2-4 grams IV over 5 minutes.
- Known hypomagnesemia: 2-4 grams IV over 5 minutes.
- For Bronchospasm: 2-4 gm IV in 100ml of NS over 20 minutes.
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Pediatric Dosage and Administration:- Severe asthma/bronchospasm: 25 mg/kg over 10 minutes. Max 2 gm
Usually mixed in 50-100 ml of NS to be given IVPB.
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.