Molecular action of class I antiarrhythmic drugs and clinical implications

This report briefly reviews the advance in our knowledge of cellular electrophysiological effects of membrane stabilizer antiarrhythmic drugs (sodium channel blockers) including some new ones. The class I drugs block cardiac sodium channels and differ in the kinetics of the interaction with sodium channels and in the actions on the repolarization phase. The class I drugs can be subdivided into subclasses (I a,b,c). This review focuses on the interaction of these drugs with sodium channels and the molecular models of their action. The interaction of class I drugs with the sodium channel receptor is influenced by the state of the myocardium (pH, ischaemia) and by other drugs as well. The clinical implications of different actions of sodium channel blockers, alone and in combination, and their proarrhythmic effects are summarized.