Quinidine and the identification of drugs whose elimination is impaired in subjects classified as poor metabolizers of debrisoquine.
Br J Clin Pharmacol
; 22(6): 739-43, 1986 Dec.
Article
en En
| MEDLINE
| ID: mdl-3567021
Quinidine and its diastereoisomer quinine were tested in vitro for their effect on the 4-hydroxylation of debrisoquine, the O-deethylation of phenacetin and the 1'-hydroxylation of bufuralol, by human liver microsomal samples; quinidine was studied for its effect on debrisoquine 4-hydroxylation in vivo. Quinidine was a potent inhibitor of the 4-hydroxylation of debrisoquine and the 1'-hydroxylation of bufuralol, with IC50 values of 0.7 and 0.2 microM, being around 100 times more potent in this respect than quinine. Very much higher (1000-fold) levels of quinidine were required to inhibit the O-deethylation of phenacetin, being rather less potent in this than quinine. Eight subjects were phenotyped for their debrisoquine oxidation status and found to be extensive metabolisers (EM). They were tested again after the co-administration of 50 mg of quinidine with the debrisoquine. The concomitant administration of quinidine increased the metabolic ratios (MRs) by a mean of 26-fold. The effects of quinidine at a dose of only 50 mg, on the metabolism of a new drug in EM subjects may prove a useful method of assessing the contribution of the debrisoquine 4-hydroxylase isozyme to the elimination of the drug tested.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Quinidina
/
Sistema Enzimático del Citocromo P-450
/
Debrisoquina
/
Oxigenasas de Función Mixta
/
Isoquinolinas
Tipo de estudio:
Diagnostic_studies
Límite:
Female
/
Humans
/
Male
Idioma:
En
Revista:
Br J Clin Pharmacol
Año:
1986
Tipo del documento:
Article
Pais de publicación:
Reino Unido