Search
antiarrhythmic agent, Group IA
Indications:
- preexcitation atrial fibrillation
- supraventricular tachycardia
- ventricular arrhythmias
- chemical cardioversion [4]
Mechanism of action:
- slows conduction & prolongs repolarization
- like other class I agents, class Ia agents inhibit Na+ influx during phase 0 of the fast sodium channel action potential
- thus class IA agents have local anesthetic & membrane stabilizing properties characteristic of all class I agents
- to a lesser extent, class IA agents also block K+ channels
- thus class Ia agents prolong the action potential duration, repolarization, ventricular refractoriness & the QT interval
Interactions
drug interactions
drug adverse effects of antiarrhythmic agent, Group IA
Specific
disopyramide (Norpace)
procainamide; novacainamide (Procan Pronestyl-SR)
quinidine [gluconate (Quinaglute, Quinalan) & sulfate (Quinidex, Quinora)]
General
antiarrhythmic agent, Group I
References
- Manual of Medical Therapeutics, 28th ed, Ewald &
McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 150
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 125
- Medical Knowledge Self Assessment Program (MKSAP) 15, 16.
American College of Physicians, Philadelphia 2009, 2012
- Deprecated Reference