RT Journal Article
SR Electronic
T1 Metabolite Formation Kinetics and Intrinsic Clearance of Phenacetin, Tolbutamide, Alprazolam, and Midazolam in Adenoviral Cytochrome P450-Transfected HepG2 Cells and Comparison with Hepatocytes and In Vivo
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1449
OP 1455
DO 10.1124/dmd.110.033605
VO 38
IS 9
A1 M. Teresa Donato
A1 David Hallifax
A1 Laura Picazo
A1 José V. Castell
A1 J. Brian Houston
A1 M. José Gomez-Lechón
A1 Agustin Lahoz
YR 2010
UL http://dmd.aspetjournals.org/content/38/9/1449.abstract
AB Cryopreserved human hepatocytes and other in vitro systems often underpredict in vivo intrinsic clearance (CLint). The aim of this study was to explore the potential utility of HepG2 cells transduced with adenovirus vectors expressing a single cytochrome P450 enzyme (Ad-CYP1A2, Ad-CYP2C9, or Ad-CYP3A4) for metabolic clearance predictions. The kinetics of metabolite formation from phenacetin, tolbutamide, and alprazolam and midazolam, selected as substrates probes for CYP1A2, CYP2C9, and CYP3A4, respectively, were characterized in this in vitro system. The magnitude of the Km or S50 values observed in Ad-P450 cells was similar to those found in the literature for other human liver-derived systems. For each substrate, CLint (or CLmax), values from Ad-P450 systems were scaled to human hepatocytes in primary culture using the relative activity factor (RAF) approach. Scaled Ad-P450 CLint values were approximately 3- to 6-fold higher (for phenacetin O-deethylation, tolbutamide 4-hydroxylation, and alprazolam 4-hydroxyaltion) or lower (midazolam 1′-hydroxylation) than those reported for human cryopreserved hepatocytes in suspension. Comparison with the in vivo data reveals that Ad-P450 cells provide a favorable prediction of CLint for the substrates studied (in a range of 20–200% in vivo observed CLint). This is an improvement compared with the consistent underpredictions (<10–50% in in vivo observed CLint) found in cryopreserved hepatocyte studies with the same substrates. These results suggest that the Ad-P450 cell is a promising in vitro system for clearance predictions of P450-metabolized drugs.