High-throughput screening for stability and inhibitory activity of compounds toward cytochrome P450-mediated metabolism.

With the advent of combinatorial chemistry and high-throughput screening technology, thousands of molecules can now be rapidly synthesized and screened for biological activity against large numbers of protein targets, greatly increasing the speed with which lead compounds are identified during the early stages of drug discovery. However, rapid optimization of parameters that determine whether a high-affinity ligand or a potent inhibitor will become a successful drug remains a challenge in improving the efficiency of the drug discovery process. Parameters that define absorption, distribution, metabolism, and excretion properties of drug candidates are important determinants of therapeutic efficacy, and thus should be optimized during early stages of drug discovery. Although the speed with which drugs are screened for properties such as absorption, cytochrome P450 (CYP) inhibition, and metabolic stability has increased over the past several years, the screening rate/capacity is still several orders of magnitude lower than those for high-throughput methods used in lead identification, resulting in a bottleneck in the drug discovery process. This review discusses current methods used in the in vitro screening of drugs for their stability toward CYP-mediated oxidative metabolism. This is a critical screen in the drug discovery process because metabolism by CYP represents an important clearance mechanism for the vast majority of compounds, thus affecting their oral bioavailability and/or duration of action.