| I |
Sodium-channel blockade |
Reduce phase 0 slope and peak of action potential |
|
|
| IA |
Moderate |
Moderate reduction in phase 0 slope; increase action potential duration; increase effective refractory period. |
Quinidine, procainamide, disopyramide |
Ventricular arrhythmias, atrial fibrillation |
| IB |
Weak |
Small reduction in phase 0 slope; reduce action potential duration; decrease effective refractory period. |
Lidocaine, tocainide, mexiletine |
Ventricular arrhythmias |
| IC |
Strong |
Pronounced reduction in phase 0 slope; no effect on action potential duration or effective refractory period. |
Flecainide, propafenone |
Paroxysmal atrial fibrillation |
| II |
Beta-blockade |
Block sympathetic activity; reduce rate and conduction |
Acebutolol, atenolol, bisoprolol, esmolol, metoprolol, nadolol, propranolol, carvedilol, labetalol |
|
| III |
Potassium-channel blockade |
Delay repolarization (phase 3) and thereby increase action potential duration and effective refractory period |
Sotalol, dofetilide, ibutilide, bretylium, amidodarone |
Ventricular arrhythmias, atrial fibrillation |
| IV |
Calcium-channel blockade |
Block L-type calcium-channels; most effective at sinoatrial and atrioventricular nodes; reduce rate and conduction |
Amlodipine, felodipine, isradipine, nicardipine, nifedine, diltiazem, verapamil |
|
