BIOL 3327 Lecture Notes - Lecture 45: Mexiletine, Lidocaine, Cardiac Arrhythmia
15 Jul 2020
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Do not block voltage-gated k+ channels so they do not exert a significant effect on the repolarization phase of action potential. Therefore, they do not prolong action potential or refractory period duration. Do not block leak na+ channels: this means they do not affect normal pacemaker activity in sa or av node. Have higher affinity for channels that are open and activated and have little to no affinity for resting na+ channels (higher degree of state-dependence than class ia drugs: primary site of action: contractile cells in the ventricles, primary therapeutic use: Ventricular arrhythmias associated with a myocardial infarction: in short, the class ib drugs exert a more. Selective block of the diseased heart tissue responsible for the arrhythmia itself: arrhythmic tissue depolarizes more often than normal tissue. Thus, na+ channels in the arrhythmic tissue spend a greater amount of time in their open states than do na+ channels in normal tissue.
