Effects of an antiarrhythmic drug A-2545 on canine ventricular arrhythmia models; comparison with mexiletine and flecainide.

Abstract

We investigated effects of a new Na+ channel blocking antiarrhythmic drug, A-2545, N-3 (2,2,5,5-tetramethyl-3-pyrroline-3-carboxamido)-propyl-phthalimide-hydro chloride, on various canine ventricular automaticity arrhythmias induced by two-stage coronary ligation, digitalis and adrenaline, and compared them with those of mexiletine. A-2545 showed antiarrhythmic effects, significantly decreasing the arrhythmic ratio of 24-h and 48-h coronary ligation-, digitalis- and adrenaline-induced automaticity arrhythmias. The antiarrhythmic plasma concentrations (IC50) of A-2545, 2 mg kg(-1) 10 min(-1), i.v., for 24-h and 48-h coronary ligation-, digitalis- and adrenaline-induced arrhythmias were 1.8, 1.3, 5.8 and 3.7 microg ml(-1), respectively, and that calculated for oral A-2545 (25 mg kg(-1)) in 24-h coronary ligation-induced arrhythmia was 1.8 microg ml(-1). A-2545 is specifically potent in suppressing coronary ligation-induced arrhythmias, i.e., decreasing the arrhythmic ratio nearly to zero by oral administration, and among the intravenously given experiments A-2545 was effective at lower concentrations than other arrhythmia models; A-2545, 2 mg kg(-1) 10 min(-1), was equipotent to 5 mg kg(-1) 10 min(-1) mexiletine in suppressing 24-h coronary ligation-induced arrhythmia, indicating that A-2545 is more potent than mexiletine. In order to determine whether A-2545 has arrhythmogenic effects, we used programmed electrical stimulation (PES)-induced reentry arrhythmias in dogs with old myocardial infarction and compared effects of A-2545 and flecainide. A-2545, 2 and 5 mg kg(-1) 10 min(-1), significantly suppressed the PES-induced arrhythmias in all six dogs without aggravating them. These arrhythmias were not markedly suppressed by flecainide either with 1 or 3 mg kg(-1) 1O min(-1); moreover even in one out of six dogs aggravation of arrhythmia was noted after 1 mg kg(-1) 10 min(-1). In conclusion, A-2545 suppressed various canine ventricular arrhythmias, and the antiarrhythmic effect of A-2545 was more potent than that of mexiletine, and A-2545 did not show arrhythmogenic effects compared to flecainide.

• Authors: Y X Xue, J Arita, N N Aye, K Hashimoto
• Journal: Naunyn-Schmiedeberg's archives of pharmacology (Naunyn Schmiedebergs Arch Pharmacol) Vol. 358 Issue 6 Pg. 649-56 (Dec 1998) ISSN: 0028-1298 [Print] Germany
• PMID: 9879724 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Anti-Arrhythmia Agents
• Pyrroles
• Mexiletine
• Flecainide
• A 2545

Topics

• Animals
• Anti-Arrhythmia Agents (pharmacology)
• Arrhythmias, Cardiac (chemically induced)
• Blood Pressure (drug effects)
• Coronary Vessels (surgery)
• Dogs
• Dose-Response Relationship, Drug
• Electric Stimulation
• Electrocardiography
• Flecainide (pharmacology)
• Heart Rate (drug effects)
• Mexiletine (pharmacology)
• Models, Biological
• Molecular Structure
• Pyrroles (blood, pharmacology)