title: Clinical and electrophysiologic studies of R61748 (transcainide): a new class Ic antiarrhythmic drug.
abstract: The electrophysiology and antiarrhythmic efficacy of R61748, a 4-OH metabolite of R54718 (transcainide), have been studied in patients and animal experiments. The results indicated that R61748 (1 mg/l) decreased the rate of rise of the transmembrane action potential (Vmax) by 40% and shortened the action potential duration (APD) by 10% in guinea-pig right ventricular papillary muscle. ERP/APD increased by 10%. The effect was dose-dependent. Clinical electrophysiologic studies (EPS) in 6 patients with ventricular premature beats showed that R61748 (0.1 mg/kg) prolonged PA duration by 30%, AH interval by 13% and HV duration by 24%. ECG revealed prolonged P duration by 16%, P-R interval by 16% and QRS duration by 17%. R61748 has also been used in 14 patients with idiopathic premature ventricular contraction (PVCs). PVCs were abolished in 6 patients and decreased more than 93% in 2 patients. The average reduction of PVCs was 80%. R61748 (0.075 mg/kg) abolished an episode of repetitive ventricular tachycardia in 1 patient. It is concluded that R61748 is a potent new class Ic antiarrhythmic agent with slow kinetics. R61748 is the 4-OH metabolite of R54718 (transcainide) (Stroobandt et al., 1987) which is a new class Ic antiarrhythmic agent. Up to now no reports have been published about R61748. This paper presents the initial studies of cellular and clinical electrophysiologic effects and the evaluation of antiarrhythmic efficacy of R61748.
authors.affiliation: Department of Cardiology, Great Wall Hospital, Beijing, China.
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.forename: T
authors.initials: T
authors.lastname: Yu
authors.forename: H
authors.initials: H
authors.lastname: Kesteloot
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000328:Adult; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology* / Q000627:therapeutic use; D005117:Cardiac Complexes, Premature / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged
chemical_list: D000889:Anti-Arrhythmia Agents; C052070:transcainide; D008012:Lidocaine