Kinetic Constants and Sample-to-Sample Variation in the Rate of Metabolism of two or more Substrates for Human Liver Microsomal CYP1A2, CYP2B6, CYP2C8, CYP2D6 and CYP3A4/5

Marker substrates for certain CYPs have changed for several reasons, including the need for improved selectivity and sensitivity, reliable substrates for LC/MS/MS analysis, and substrates that provide greater repeatability. The objectives of this study were to compare sample-to-sample variation in cytochrome P450 enzymatic rates between two or more CYP-specific substrates and to determine Michaelis-Menten kinetic constants (Km and Vmax) for these same reactions using a pool of human liver microsomes.