Electrophysiological  properties of mexiletine assessed with respect to plasma concentrations.
Electrophysiological measurements were made before and after the intravenous administration of mexiletine in 14 patients with preexcitation syndromes. Following a single infusion of 3 mg/kg body weight plasma concentrations of mexiletine fell rapidly and after 15 min, significant changes in electrophysiological measurements were not found. Higher plasma mexiletine concentrations, bringing about a pharmacological effect, were attained when a second intravenous infusion was also given. The results suggest a minimum effective plasma concentration for mexiletine of about 0.5 mg/l. Side-effects were minimal and their production was largely dependent on the rate of drug infusion. Electrophysiological measurements in previous studies may have been made at a time when plasma mexiletine concentrations were below an effective level and this could explain a disparity in their findings.
D000293:Adolescent; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000188:drug therapy*; D004594:Electrophysiology; D005260:Female; D006321:Heart / Q000502:physiology; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008297:Male; D008801:Mexiletine / Q000097:blood* / Q000627:therapeutic use; D008875:Middle Aged; D011437:Propylamines / Q000097:blood*
D011437:Propylamines; D008801:Mexiletine