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Drug Metab Dispos ; 29(6): 813-20, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11353749

RESUMEN

Etoricoxib, a potent and selective cyclooxygenase-2 inhibitor, was shown to be metabolized via 6'-methylhydroxylation (M2 formation) when incubated with NADPH-fortified human liver microsomes. In agreement with in vivo data, 1'-N'-oxidation was a relatively minor pathway. Over the etoricoxib concentration range studied (1-1300 microM), the rate of hydroxylation conformed to saturable Michaelis-Menten kinetics (apparent K(m) = 186 +/- 84.3 microM; V(max) = 0.76 +/- 0.45 nmol/min/mg of protein; mean +/- S.D., n = 3 livers) and yielded a V(max)/K(m) ratio of 2.4 to 7.3 microl/min/mg. This in vitro V(max)/K(m) ratio was scaled, with respect to yield of liver microsomal protein and liver weight, to obtain estimates of M2 formation clearance (3.1-9.7 ml/min/kg of b.wt.) that agreed favorably with in vivo results (8.3 ml/min/kg of b.wt.) following i.v. administration of [(14)C]etoricoxib to healthy male subjects. Cytochrome P450 (P450) reaction phenotyping studies-using P450 form selective chemical inhibitors, immunoinhibitory antibodies, recombinant P450s, and correlation analysis with microsomes prepared from a bank of human livers-revealed that the 6'-methyl hydroxylation of etoricoxib was catalyzed largely (approximately 60%) by member(s) of the CYP3A subfamily. By comparison, CYP2C9 (approximately 10%), CYP2D6 (approximately 10%), CYP1A2 (approximately 10%), and possibly CYP2C19 played an ancillary role. Moreover, etoricoxib (0.1-100 microM) was found to be a relatively weak inhibitor (IC(50) > 100 microM) of multiple P450s (CYP1A2, CYP2D6, CYP3A, CYP2E1, CYP2C9, and CYP2C19) in human liver microsomes.


Asunto(s)
Inhibidores de la Ciclooxigenasa/farmacocinética , Sistema Enzimático del Citocromo P-450/metabolismo , Isoenzimas/metabolismo , Microsomas Hepáticos/enzimología , Piridinas/farmacocinética , Sulfonas/farmacocinética , Animales , Línea Celular , Ciclooxigenasa 2 , Inhibidores de la Ciclooxigenasa 2 , Inhibidores Enzimáticos del Citocromo P-450 , ADN Complementario , Etoricoxib , Humanos , Isoenzimas/antagonistas & inhibidores , Isoenzimas/efectos de los fármacos , Masculino , Proteínas de la Membrana , Prostaglandina-Endoperóxido Sintasas/efectos de los fármacos
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