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Reevaluation of digoxin-encainide interactions using an animal model
E Weinhouse1, J Tribble, M Jarenwattananon
1Department of Pediatrics, Medical College of Wisconsin, Milwaukee.
Clinical Cardiology
|July 1, 1988
Summary
Encainide worsened digoxin-induced atrial ectopic tachycardia (AET) in rats, increasing arrhythmias and mortality. Caution is advised when coadministering these drugs due to potential proarrhythmic effects.
Area of Science:
- Pharmacology
- Cardiology
- Toxicology
Background:
- Digoxin is a cardiac glycoside used to treat heart failure and arrhythmias.
- Atrial ectopic tachycardia (AET) is a type of irregular heartbeat.
- Encainide is an antiarrhythmic drug.
Purpose of the Study:
- To investigate the effects of encainide on digoxin-induced AET in rats.
- To assess the potential for drug-drug interactions between digoxin and encainide.
Main Methods:
- Rats were administered digoxin to induce AET.
- Encainide or saline was administered intravenously at varying doses.
- Electrocardiography was used to monitor cardiac activity.
- Serum digoxin levels were measured using immunoassay.
Main Results:
- Encainide converted digoxin-induced AET to ventricular arrhythmias at all tested doses.
- Encainide prolonged recovery time and increased mortality in digoxin-treated rats.
- Encainide alone, without digoxin, caused a dose-related increase in the P-R interval.
Conclusions:
- Encainide exhibits a proarrhythmic effect, exacerbating digoxin-induced arrhythmias in rats.
- Co-administration of digoxin and encainide warrants caution due to potential adverse cardiac events.