Anti-arrhythmic drug classification by action potential effects
THE CONTEXT
Anti-arrhythmic drugs are grouped by their principal channel or receptor effects and their effects on the intracellular action potential. Some drugs fall outside this classification or have properties spanning multiple classes.
Class I: sodium channel blockers
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Class I drugs are membrane-stabilising agents that block sodium channels.
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The subgroup that prolongs the action potential includes quinidine and disopyramide.
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The subgroup that shortens the action potential includes lidocaine and mexiletine.
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The subgroup with no effect on the action potential includes flecainide and propafenone.
Classes II, III and IV
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Class II drugs are β-adrenoceptor antagonists, or β-blockers; examples are atenolol, bisoprolol and metoprolol.
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Class III drugs primarily prolong the action potential; examples are amiodarone, dronedarone and sotalol.
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Class IV drugs are slow calcium channel blockers; examples are verapamil and diltiazem.
Limits of the classification
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Digoxin, ivabradine and adenosine have no place in this classification.
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Amiodarone has properties belonging to more than one class.