Magnesium Sulfate

Question 1

Drug classification

Answer 1

Electrolyte/antidysrythmIc

Question 2

Mechanism of action

Answer 2

SMC Ca2+ channel blocker -> inhibits calcium channel entry and the subsequent interaction between actin and myosin in smooth muscle cells-> smooth muscle relaxation and dilation of blood vessels and bronchial tree

CARDIAC Ca2+ channel blocker-> negative chronotropy, inotropy, dromotropy

Question 3

Pharmacokinetics

Onset of action
Peak effects
Duration of effects
Half life

Answer 3

• Onset of action- immediate IV, 1 hour IM
• Peak effects- varies
• Duration of effects- 1 hour
• Half life- n/a

Question 4

Indications/field use

Answer 4

• Severe asthma/bronchospasms
• severe refractory VF or pulseless VT with hypoMg2+, torsades de points
• eclampsia

Question 5

Contraindications

Answer 5

3rd degree heart block, hypotension

Question 6

Side effects/adverse reactions

Answer 6

Sweating, flushing, itching, rash. Bradycardia, hypotension, drowsiness, respiratory depression. Dysrhythmias

Question 7

Dose

Answer 7

ADULT:
Asthma: 2g in 100cc NS IV/IO infusion over 10 minutes
VT/VF/Torsades no pulse: 2g IV/IO over 1-2 minutes
VT/Torsades with pulse: 1-2g in 50-100cc NS IV/IO over 5-60 minutes
Eclampsia- 4g in 20mL IV/IO over 5 minutes

PEDI:
Asthma- 25-50 mg/kg IV/IO infusion over 15-30 min MAX DOSE 2g
VT/Torsades no pulse- 25-50mg/kg IV/IO MAX DOSE 2g
VT/Torsades with pulse- 25-50mg/kg IV/IO over 10-20 minutes MAX DOSE 2g

Question 8

Precautions

Answer 8

Caution with impaired renal failure

Watch for respiratory depression

Question 9

Drug-drug interaction

Answer 9

Cardiac conduction abnormalities if given with digitalis

Question 10

Infusion Sheet

Answer 10

Magnesium Sulfate 5g in 10cc= .5g per cc

​Asthma: 2 grams in 100cc over 10 minutes
​VT/VF Torsades without a pulse

2cc from a 10cc vial= 1 gram
4cc from a 10cc vial= 2 grams
8cc from a 10cc vial= 4 grams