An examination of IC50 and IC50-shift experiments in assessing time-dependent inhibition of CYP3A4, CYP2D6 and CYP2C9 in human liver microsomes.
The relationship between time-dependent inactivation (TDI) and IC50 is examined using a consolidated method for evaluating CYP450 inhibition during drug discovery. An IC50 fold-shift of >1.5 indicated significant TDI potency. Further, the "shifted IC50" could be used to estimate, the K(I) and TDI potency ratio k(inact)/K(I) to within 2-fold in most cases.
Pharmacokinetics and Drug Metabolism, Amgen, Inc., 1 Kendal Sq., Cambridge, MA 02139, USA. loren.berry@amgen.com
Loren M
LM
Berry
Zhiyang
Z
Zhao
D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors*; D065729:Cytochrome P-450 CYP2C9; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D051544:Cytochrome P-450 CYP3A; D065692:Cytochrome P-450 CYP3A Inhibitors; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D008954:Models, Biological; D013997:Time Factors
D065690:Cytochrome P-450 CYP2D6 Inhibitors; D065692:Cytochrome P-450 CYP3A Inhibitors; D004791:Enzyme Inhibitors; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human