For high throughput screens, the quickest methodology possible is desirable, but a substantial amount of potentially useful information is lacking since most screens for metabolic stability are conducted at one concentration, and sometimes at one time point. Information that would benefit projects during the discovery phase are to know the metabolic rate linearity (K(m) value) and projected hepatic clearance (CL(h) value), which is possible by the addition of one more concentration. This study used the FDA-preferred probe cytochrome P450 substrates to determine K(m), V(max), and CL(int) values. The results showed that compounds with relatively high metabolic rates produced more accurate and reproducible results that match well with predicted K(m) values according to the FDA. On the other hand, compounds with relatively low metabolic rates yielded more variable results. Thus, the use of two substrate concentrations should be useful with screening assays for assessing the kinetic values for other compounds.