The stability of test compounds (1 µM) were measured following incubation at 37 °C with cryopreserved hepatocytes in suspension at a cell density of 0.5 million cells per mL. Incubates were prepared in duplicate with aliquots removed at seven time points over a period of 120 minutes and reactions terminated and compound extracted by the addition of acetonitrile containing an analytical internal standard. The disappearance of the parent compounds were monitored by LC-MS/MS and half-life values determined over the course of the incubation. The half-life values obtained were used to calculate their in vitro intrinsic clearance expressed as µL/min/million cells.