Magnesium Sulfate

Question 1

What is Magnesium Sulfate’s trade name?

Answer 1

N/A

Question 2

What class is Magnesium Sulfate?

Answer 2

electrolyte, anticonvulsant

Question 3

What is Magnesium Sulfate’s mechanism of action?

Answer 3

reduces striated muscle contractions and blocks peripheral NT release at the myoneural junction (relaxes smooth muscle)

Question 4

When is Magnesium Sulfate used?

Answer 4

• in the management of seizures associated with toxemia of pregnancy. Also used for urine relaxation, bronchodilator (post beta agonist and anticholinergic agents)
• also used for magnesium deficiency

Question 5

Indications for Magnesium Sulfate

Answer 5

• seizures of eclampsia (toxemia of pregnancy)
• cardiac arrest only if torsades de pointes is suspected or hypomagnesium is present
• life-threatening ventricular dysrhythmias attributable to digitalis toxicity
• suspected hypomagnesemia
• status asthmaticus not responsive to beta adrenergic drugs

Question 6

Contraindications for Magnesium Sulfate

Answer 6

• heart block or myocardial damage
• hypermagnesemia or hypercalcemia
• diabetic coma

Question 7

Adverse reactions to Magnesium Sulfate

Answer 7

• diaphoresis
• facial flushing
• hypotension
• depressed reflexes
• hypothermia
• bradycardia
• circulatory collapse
• respiratory depression/arrest
• diarrhea
• nausea and vomiting

Question 8

Dose of Magnesium Sulfate- Seizure activity associated with pregnancy

Answer 8

• 4g diluted in NS for IV piggyback
• load over 15-20 minutes
• continuous infusion of 1-2g/hour
• max dose of 30-40 g/d

Question 9

Dose of Magnesium Sulfate- Pulseless Arrest (Tosades de Pointes or Hypomagnesia)

Answer 9

Adult: 
- 1-2g diluted in 10mL of NS IV/IO push
Pediatric:
- 25-50mg/kg IV/IO push 
- max dose of 2g
- over 10-20 minutes

Question 10

Onset

Answer 10

IV= immediate 
IM= 3-4 hours

Question 11

Duration

Answer 11

IV= 30 minutes 
IM= 3-4 hours

Question 12

Route

Answer 12

IV, IO, IM

Question 13

Special Considerations

Answer 13

• Pregnancy: Category A
• Convulsions may occur up to 48 hours after delivery
• The “cure” for toxemia is delivery of the baby
• Must be used with caution in patients with renal failure because it is cleared by the kidneys and can reach toxic levels easily in those patients