In vivo drug metabolism model for human cytochrome P450 enzyme using chimeric mice with humanized liver

✍ Scribed by Miki Katoh; Toshiro Sawada; Yoshinori Soeno; Miki Nakajima; Chise Tateno; Katsutoshi Yoshizato; Tsuyoshi Yokoi

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 150 KB
• Volume: 96
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.20783

✦ Synopsis

We previously clarified that major human drug metabolizing enzymes were expressed in a chimeric urokinase-type plasminogen activator (uPA)+/+/severe combined immunodeficient (SCID) mouse line established recently, in which the liver could be replaced by more than 80% with human hepatocytes. In the present study, we investigated the in vivo drug metabolism of a CYP2D6 substrate, debrisoquin (DB), in chimeric mice with high (High) or low (Low) human albumin (hAlb) concentrations and in control uPA-/-/SCID mice. The hAlb in the mouse blood is one of the indices of humanized liver because the chimeric mice produce hAlb. After oral administration of DB at 2.0 mg/kg, the AUC0-8 value of a major CYP2D6 metabolite of DB, 4'-hydroxydebrisoquin (4-OH DB), in High was 3.6-fold higher than those of Low and uPA-/-/SCID mice. By pre-treatment with a typical CYP2D6 inhibitor, quinidine, the AUC0-8 value of 4-OH DB in High was decreased although such values in Low and uPA-/-/SCID mice did not change. The in vitro kinetic analyses and the Ki values of quinidine on the DB 4'-hydroxylase activity in liver microsomes also supported the humanization of the chimeric mice. In conclusion, the chimeric mice exhibited a humanized profile of drug metabolism and the inhibition of P450.