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Class I: |
Bind to sodium channel, decrease speed of depolarization. |
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Class Ia: |
Slow Upstroke of action potential, prolong duration of action potential, decrease conductivity, increases refractoriness.
Quinidine, Procainamide, Disopyramide |
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Class Ib: |
Minimal effect on upstroke of action potential, shorten duration of action potential, decreases refractoriness.
Lidocaine, Phenytoin, Tocainide, Mexiletine |
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Class Ic: |
Marked slowing of upstroke of action potential, minimal effect on action potential duration, marked decrease in conductivity, little effect on refractoriness.
Flecanide, Encainide, Propafenone |
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Class II:
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Beta blocking drugs, decrease sympathetic tone, affects mainly SA and AV nodes, affect is indirect by blocking beta receptors.
Atenolol, Labetolol, Metropolol, Nadolol, Propranolol, Timolol |
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Class III: |
Increase action potential duration.
Amiodarone, Bretylium, Sotalol, Procainamide |
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Class IV: |
Calcium channel blockers, affects mainly SA and AV nodes, affect is direct because SA and AV node depolarization is controlled by slow calcium channels.
Diltiazem, Verapamil |
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Class V: |
Digitalis Agents, increased parasympathetic activity
Digoxin, Digitalis |
Source; Richard Fogoros, Electrophysiology Testing |
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