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Absolute bioavailability in man of N‐acetylprocainamide determined by a novel stable isotope method
Author(s) -
Strong John M.,
Dutcher John S.,
Lee WoongKu,
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/cpt1975185part1613
Subject(s) - napa , bioavailability , chemistry , absorption (acoustics) , pharmacokinetics , urine , oral administration , capsule , pharmacology , chromatography , medicine , biochemistry , biology , materials science , botany , composite material
Absorption of a single oral dose of N‐acetylprocainamide (NAPA) was studied in 3 normal subjects. Approximately 85% of the oral dose was absorbed and peak plasma NAPA concentrations were reached in 45 to 90 min. In 2 subjects, NAPA was absorbed at a fast initial rate, then more slowly, prolonging the apparent elimination phase half‐life. Absolute bioavailability was determined by a new stable isotope method that entailed intravenous injection of NAPA− 13 C at the same time that an unlabeled NAPA capsule was given orally. Plasma levels and urine excretion of both compounds were determined by mass fragmentography. Bioavailability was assessed by deconvoluting the plasma level vs time curves resulting from intravenous and oral drug administration, and also by comparing the relative percentage of NAPA and NAPA− 13 C excreted unchanged in the 24 hr after simultaneous administration.