Vaughan-Williams Classification

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• Classification system for anti-arrhythmic drugs


Class I:

Local anaesthetic action, reducing Na Current - Sodium Channel Blockade:

IA Prolong Repolarization

Quinidine

IB Shortern Repolarization

Lidocaine

IC Little effect on repolarization

Encainide


Class II:

Beta-blockade

Propanolol


Class III:

Action potential prolongation (Potassium channel blockade + inactivated Na+ channels)

Amiodarone


Class IV:

Calcium channel blockade

Verapimil


Miscellaneous:

Adenosine - Specific to AV node, hyperpolarises cell membrane.  t1/2 = 8-10 seconds

Digitalis

Magnesium