High-Throughput Miniaturization of Cytochrome P450 Inhibition Screening Using the Echo Liquid Handler

Cytochrome P450 enzymes are the largest group of drug-metabolizing enzymes and their potential interactions with drug candidates could lead to idiosyncratic toxicity. CYP3A4 is the most abundant cytochrome P450 enzyme in the liver and plays a major role in metabolizing xenobiotics. The Promega P450-Glo™ CYP3A4 Assay (Luciferin-IPA) offers a sensitive, specific and high-throughput luminescence assay for the examination of CYP3A4 inhibition. In this application note the Echo® 555 liquid handler from Labcyte was used for the miniaturization and optimization of the P450-Glo™ Assay with pooled Human Liver Microsomes (HLM). The transfer of enzymes, buffers, microsomes, inhibitors and substrates in small volumes to provide a sensitive and robust assay is demonstrated. Comparable IC50 values for four known CYP3A4 inhibitors are presented.