Elucidation of pharmacokinetics of novel DNA ligase I inhibitor, S012-1332 in rats: Integration of in vitro and in vivo findings.

S012-1332 is the first DNA ligase I inhibitor that demonstrated in vivo anti-breast cancer activity. The present study aimed to assess the in vivo pharmacokinetics of S012-1332 in rats and interpret them with in vitro findings. A sensitive and selective liquid chromatography-tandem mass spectrometry bioanalytical method was developed and validated to determine S012-1332. Following oral administration, the absolute bioavailability was 7.04%. The absorption was prolonged which can be explained by low solubility in simulated gastric fluid and several folds higher solubility in simulated intestinal fluid. The effective permeability across the intestinal membrane in in situ single pass perfusion study for S012-1332 was 5.58 ± 1.83 * 10-5 cm/sec compared to 5.99 ± 0.65 * 10-5 cm/sec for carbamazepine, with no significant difference, indicating S012-1332 has high permeability. It was rapidly partitioning into plasma in blood, where it was stable. Plasma protein binding was moderate which may have attributed to the rapid distribution out of the vascular compartment. The pharmacokinetics of S012-1332 was characterized by extensive clearance as seen with rat liver and intestinal microsomes. In vitro results elucidate the in vivo pharmacokinetic data. These findings provide crucial information for further development of S012-1332 as anti-breast cancer agent.