Anti Arrhythmic Drugs

Question 1

Classify anti arrythmic drugs

Answer 1

class 1

Sodium channel blockers
★prolonged repolarization
-quinidine,procainamide,disopyramide,morcizine
★shorten repolarization
-lignocain phenotoin
★little effect on repo
-encanide,flecainide,propafanone

B adrenergic blockers
(Reduce sympathetic tone)
-propanalol,acebutolol,esmolol

K channel blockers
(Prolong repolarization)
Amiodarone,dronadarone,vernakalant,sotalol

Ca channel blockers
(Prolong conduction and refractoriness specially in SA and AV nodes)
Verampil,diltiazem

Question 2

Who classified anti arrythmic drugs

Answer 2

Vaughan williams

Question 3

Mechanism of action of anti arrythmic drugs

Answer 3

Na channel blockers
Depression of phase 0 depolarisation
Prolonged ApD and ERP
Slowing of conduction velocity
Supression of abnormal automacity

1.quinidine -depresses all cardiac properties
Automacity, rhythmicity, excitability,conduction velocity prolongs repolarization

2.procainamide -better tolerated than quinidine
Can cause SLE

3.disopyramide-2nd line drugs for ventricular arrythmias

4. Lignocain
   Used in ventricular arrythmias not used in atrial arrythmias

5.phentoin
Anti epileptic, ventricular arrythmias,digitalis induced arrythmias

6.flecanide etc are not used due to risk of cardiac arrest

B blockers
Depression myocardial activity, automacity, conduction velocity reduce membrane response and amplitude of action potential depression av conduction

1.propanol
Supraventricular arrythmias,sinus tachycardia,atrial and nodal extrasystoles and digitalis induced arrythmias