Electrophysiological effects of encainide and its metabolites in 11 patients.
Encainide is a new antiarrhythmic class IC agent. Eleven patients were given 1 mg/kg of encainide i.v. over a 15-min period. Electrophysiological studies were done before and l h after drug administration. Blood levels of encainide and its principle metabolites O-demethyl-encainide, 3 metoxy-O-demetyl-encainide and N-demethyl-encainide were measured serially after drug administration. Heart rate, blood pressure, and conduction intervals were monitored. Sixty minutes after drug administration there was a marked increase of the QRS, PA, AH, and HV intervals of 28.1% (p less than 0.01), 17.2% (p less than 0.01), 22.4% (p less than 0.01), and 32.2% (p less than 0.01), respectively, and a slight increase of the Wenckebach cycle length of 8% (p less than 0.05). BP, RR, QT, CSNRT, ESACT, ERP, and FRP did not vary significantly. The HV interval already was increased significantly 2 min after drug administration, while AH was not increased until 15 min after drug administration. The average blood levels of encainide and ODE 60 min after drug administration were 0.410 +/- 0.12 and 0.176 +/- 0.09 microgram/ml, respectively (mean +/- SE of the mean). There was a positive correlation between the increase of the AH and the blood level of ODE, which points out the importance of prolonged electrophysiological studies when testing drug with possibly active metabolites.
Libersa
C C
CC
Lekieffre
J P
JP
Caron
J F
JF
Poirier
J M
JM
Pladys
A M
AM
Kacet
S
S
Kher
A R
AR
D000328:Adult; D000368:Aged; D000813:Anilides / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology*; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology*; D001283:Atrioventricular Node / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D004562:Electrocardiography; D004594:Electrophysiology; D016700:Encainide; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged
D000813:Anilides; D000889:Anti-Arrhythmia Agents; D016700:Encainide