A novel relay method for determining low-clearance values.
A novel relay method has been developed using cryopreserved human hepatocytes to measure intrinsic clearance of low-clearance compounds. The relay method involved transferring the supernatant from hepatocyte incubations to freshly thawed hepatocytes at the end of the 4-h incubation to prolong the exposure time to active enzymes in hepatocytes. An accumulative incubation time of 20 h or longer in hepatoctyes can be achieved using the method. The relay method was validated using seven commercial drugs (diazepam, disopyramide, theophylline, timolol, tolbutamide, S-warfarin, and zolmitriptan) that were metabolized by various cytochrome P450s with low human in vivo intrinsic clearance at approximately 2 to 15 ml · min⁻¹ · kg⁻¹. The results showed that the relay method produced excellent predictions of human in vivo clearance. The difference between in vitro and in vivo intrinsic clearance was within 2-fold for most compounds, which is similar to the standard prediction accuracy for moderate to high clearance compounds using hepatocytes. The relay method is a straightforward, relatively low cost, and easy-to-use new tool to address the challenges of low clearance in drug discovery and development.
Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA. li.di@pfizer.com
Li
L
Di
Patrick
P
Trapa
R Scott
RS
Obach
Karen
K
Atkinson
Yi-An
YA
Bi
Angela C
AC
Wolford
Beijing
B
Tan
Thomas S
TS
McDonald
Yurong
Y
Lai
Larry M
LM
Tremaine
D001681:Biological Assay / Q000379:methods; D001711:Biotransformation; D002458:Cell Fractionation / Q000379:methods; D002478:Cells, Cultured; D015925:Cryopreservation; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D022781:Hepatocytes / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D015203:Reproducibility of Results; D013347:Subcellular Fractions / Q000201:enzymology
D004364:Pharmaceutical Preparations; D003577:Cytochrome P-450 Enzyme System