Class I Antiarrhythmic Drugs

Question 1

Sub-Classes of Class I Antiarrhythmic Drugs

Drug Names

Answer 1

Ia: Disopyramide, Procainamide, Quinidine
Ib: Lidocaine, Mexiletine
Ic: Flecainide, Propafenone

Question 2

Indications

Answer 2

Management of acute ventricular arrhythmias during cardiac surgery or MI

Question 3

Mechanism of Action

Answer 3

Blocks the sodium channels in the cell membrane during an action potential

Question 4

Actions

Answer 4

Decreases depolarization, decreasing automaticity of the ventricular cells; increases ventricular fibrillation threshold

Question 5

Contraindications

Answer 5

Allergy, bradycardia or heart block, CHF, hypotension or shock, electrolyte disturbances

Question 6

Adverse Effects

Answer 6

CNS effect: dizziness, fatigue, slurred speech
GI: nausea and vomiting
CV: arrhythmias
Respiratory depression
Misc.: rash, loss of hair, and potential bone marrow suppression

Question 7

Drug-Drug Interactions

Answer 7

Quinidine & Digoxin
Oral anticoagulants
Digoxin and Beta-blocks

Question 8

Drug-Food Interactions

Answer 8

Foods that alkalinize the urine (citrus juice, vegetables, antacids, milk products)
Grapefruit juice