High-Throughput Screening of Human Cytochrome P450 Inhibitors Using Fluorometric Substrates: Methodology for 25 Enzyme/Substrate Pairs

This chapter provides a detailed description of methodology used to assess the cytochrome P450 inhibition potential of small molecules using fluorometric substrates in a multiwell plate format. Inhibition of cytochromes P450 can result in drug-drug interactions or, in some cases, therapeutic benefit. Because of the safety and economic concerns (clinical failure or product withdrawal), screening of drug candidates for cytochrome P450 inhibition potential is nowadays conducted much earlier in the drug development process. At this stage, much larger numbers of drug candidates are in need of evaluation. Thus, safety, economic, and throughput pressures have forced the development of assays that are rapid throughput but have high predictive value. Fluorometric assays incorporating recombinant human enzymes are ideally suited for this purpose.