RT Journal Article
SR Electronic
T1 Inhibition Kinetics of Monoclonal Antibodies against Cytochromes P450
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 701
OP 708
DO 10.1124/dmd.30.6.701
VO 30
IS 6
A1 Qin Mei
A1 Cuyue Tang
A1 Yuh Lin
A1 Thomas H. Rushmore
A1 Magang Shou
YR 2002
UL http://dmd.aspetjournals.org/content/30/6/701.abstract
AB Monoclonal antibodies (MAbs) inhibitory to individual cytochromes P450 (P450s) are of tremendous utility in identification of P450s responsible for the metabolism of a given drug or drug candidate in pharmaceuticals. In the present study, two inhibitory MAbs against CYP2D6 (MAb2D6–50, IgG2b and MAb2D6–184, IgG2a) were developed by hybridoma technology to exhibit their high specificity and potency. The MAbs were further employed to assess the quantitative role (47–93%) of CYP2D6 to the metabolism of bufuralol in human liver microsomes from seven donors. Together with the MAb inhibitory to CYP3A4 as previously reported (Mei et al., 1999), the MAbs were used to study the inhibition kinetics of dextromethorphan O-demethylation (CYP2D6), testosterone 6β-hydroxylation (CYP3A4) and aflatoxin B1 3-hydroxylation (CYP3A4), respectively, with an adequate size of sample measurement. A kinetic model was proposed to fit the experimental observations with three-dimensional nonlinear regression, thereby resulting in a solution of kinetic parameters, i.e.,KI , KS ,Vmax, α, and β (changes inKI or KS andVmax in the presence of the MAb). As a result, dissociation constants (KI ) of the MAbs for the enzymes and the maximal inhibition (β) values for the P450-catalyzed reactions were predicted to have 0.04 to 0.25 μM and ≥94%, respectively. The results have demonstrated that the model can accurately predict the kinetic parameters and provide some insights into the understanding of the mechanism of MAb interaction with P450 enzyme in nature and the applications of the MAbs in qualitative and quantitative identification of P450s involved in drug metabolism. The American Society for Pharmacology and Experimental Therapeutics