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Antiarrhythmic potency of N‐acetylprocainamide
Author(s) -
Elson James,
Strong John M.,
Lee Woong-Ku,
Atkinson Arthur J.
Publication year - 1975
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1975172134
Subject(s) - procainamide , napa , metabolite , potency , pharmacology , plasma levels , active metabolite , pharmacokinetics , chemistry , medicine , in vitro , biochemistry
Compared to procainamide in an animal arrhythmia model, the antiarrhythmic potency of the N‐acetylated metabolite of procainamide (NAPA) was 92% with respect to dose and 70% with respect to plasma level. The antiarrhythmic effects of combinations of the drugs were additive. Measurements of procainamide and NAPA plasma levels needed to suppress ventricular extrasystoles suggested that both compounds are nearly equipotent in patients as well. The average plasma level required for arrhythmia control in these patients was equivalent to 5.1 mcg/ml procainamide. Since patients on long‐term procainamide therapy have plasma concentrations of NAPA that are usually comparable to, and occasionally greater than, their procainamide levels, dose regimens based on procainamide levels alone need revision to include consideration of the levels of this metabolite.