Name: Lidocaine (Zylocaine)
Class: Antidysrhythmic Agent (Class IB)
Mechanism: Shortens phase 3 repolarization. Little change in action potential duration. Inhibits arrhythmias caused by abnormal automaticity. Rapid speed of dissociation from Na+ channels.
Absorption: IV
Dist.:
Metabolism.: Hepatic.
Excretion, t½:
Toxicity/S.E.s: Fairly wide therapeutic index. Proarrhythmic effects, negative inotropy, infranodal conduction block. Drowsiness, slurred speech, paresthesia, agitation, confusion, convulsions, resp. depression, tinnitus, muscle twitching, psychosis, seizures. CNS toxicity if used w/tocainide or mexiletine (e.g., seizures).
Utility: DOC for sustained ventricular tachycardia. Treat ventricular arrhythmias arising during myocardial ischemia or digitalis-induced VA.
Special Features: Class IB drugs have the lowest potency as Na+ channel blockers.