Premium
Quinidine kinetics after a single oral dose in relation to the sparteine oxidation polymorphism in man.
Author(s) -
Brosen K,
Davidsen F,
Gram LF
Publication year - 1990
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.1990.tb03628.x
Subject(s) - quinidine , sparteine , debrisoquine , hydroxylation , chemistry , cytochrome p450 , cyp2d6 , metabolism , pharmacology , kinetics , isozyme , oral administration , pharmacokinetics , metabolic clearance rate , metabolite , endocrinology , biochemistry , biology , enzyme , stereochemistry , physics , quantum mechanics
The kinetics at a single oral dose (400 mg) of quinidine were studied in four extensive metabolizers (EM) and four poor metabolizers (PM) of sparteine. The clearance of quinidine by 3‐hydroxylation was significantly lower in PM than in EM, but the difference was small (25‐ 30%). This finding suggests that 3‐hydroxylation, in part, is catalyzed by the same isoenzyme of cytochrome P450, P450db1 which oxidizes sparteine. Otherwise, no significant phenotypic differences in total or metabolic clearance were found and it is concluded that the metabolism of quinidine is largely carried out by P450 isoenzymes different from P450db1. A biexponential decline in the log plasma quinidine concentration vs time curves was observed in all subjects, and the mean elimination half‐life was 11‐12 h. This is about twice as long as generally reported in the literature.