MAGNESIUM SULFATE

Question 1

Drug classification

Answer 1

Electrolyte / Antidysrhythmic

Question 2

Mechanism of Action

Answer 2

• SMC* Ca2+channel blocker →inhibits calcium 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

Answer 3

Onset of Action = Immediate IV
Peak Effects = Varies
Duration of Effect = 1 hour
Half-Life = N/A

Question 4

Indications/Field Use

Answer 4

Severe Asthma / Bronchospasm
Severe refractory VF or pulseless VT w/ hypoMg2+
Torsades de Pointes
Eclampsia

Question 5

Contraindications

Answer 5

3°heart block

Hypotension

Question 6

Side effects/Adverse reactions

Answer 6

Bradycardia, dysrhythmias, hypotension, respiratory depression, drowsiness, sweating, flushing, itching, rash

Question 7

Dose

Answer 7

Asthma:
A: 2g in 200cc NS IV/IO infusion over 10 min
P: 25-50mg/kg (max dose 2g) IV/IO infusion over 15-30 min

Cardiac Arrest:
A &P: 25-50mg/kg (max dose 2g) IV/IO over 1-2 minutes

Torsades:
A: 1-2g in 50-100cc NS IV/IO over 5 minutes
P: 25-50mg/kg (max dose 2g) IV/IO over 10-20 minutes

Eclampsia:
A: 4g in 100cc NS over 10 minutes, then 1g/hr maintenance infusion
P: Not recommended

Question 8

Precautions

Answer 8

caution with impaired renal function

Watch for respiratory depression

Question 9

Drug Interactions

Answer 9

Cardiac conduction abnormalities if given with digitalis