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Kinetics of N ‐acetylprocainamide deacetylation
Author(s) -
Stec G Paul,
Ruo Tsuen I,
Thenot JeanPaul,
Atkinson Arthur J,
Morita Yoshio,
Lertora Juan J L
Publication year - 1980
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 - 10.1038/clpt.1980.218
Subject(s) - napa , acetylation , procainamide , chemistry , kinetics , pharmacology , medicine , biochemistry , gene , physics , quantum mechanics
The kinetics of N ‐acetylprocainamide (NAPA) deacetylation to procainamide (PA) were determined in a normal subject using NAPA‐ 13 C, labeled in the acetyl group. The deacetylation clearance of NAPA (Cl D ) was found to be 6.5 ml/min whereas total NAPA elimination clearance was 231 ml/min, so that 2.8% of the administered NAPA‐ 13 C was metabolized by deacetylation. This estimate of Cl D was shown to be representative of the rate of NAPA deacetylation in four patients on long‐term NAPA therapy. Steady‐state [PA]/[NAPA] ratios averaged 0.024, but would be expected to rise to 0.057 if functionally anephric patients were treated with NAPA. Despite reports that patients with the PA‐induced systemic lupus erythematosus–like reaction have had symptomatic and immunologic remission when switched to NAPA, the demonstration that NAPA is deacetylated to PA indicates that the apparently greater immunologic safety of NAPA may be relative rather than absolute. Clinical Pharmacology and Therapeutics (1980) 28, 659–666; doi: 10.1038/clpt.1980.218