The UPLC-MS/MS Method for Determination of a Novel Enterovirus 71 Inhibitor in Rat Plasma and its Application to Pharmacokinetic Study

Background: TJAB1099 is a novel, highly active inhibitor of human enterovirus 71 (HEV71), which is a most commonly found virus leading to Hand-Foot-Mouth Disease (HFMD). However, the TJAB1099 could not be detected in the plasma using a regular HPLC-UV detection during the pharmacokinetic study due to the poor solubility, which in turn limited the release prior to be absorbed by the gastrointestinal tract. Objective: The objectives of the present study were to improve the solubility of TJAB1099 by preparing formulation and develop an Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS) method applied to the pharmacokinetic study. Methods: The TJAB1099 was prepared as a phospholipid complex that intends to increase the watersolubility and subsequently improving TJAB1099 exposed in the circulation system. A highly sensitive UPLC-MS/MS method was developed for the pharmacokinetic study, in which the pharmacokinetic parameters were determined following oral and intravenous administration of 5 mg/kg and 1 mg/kg of TJAB1099 in rats, respectively. Results: The precisions for the method were less than 12.8%, while the accuracies were in the range of 90.8 - 98.0% and 96.1 - 99.6% for within-day and between-day, respectively. The mean recoveries for TJAB1099 and terfenadine (internal-standard, IS) were 85.0 ± 5.4% and 92.4 ± 4.1%, respectively. The pharmacokinetic study revealed that the Cmax of TJAB1099 after oral administration can reach 6.84 ± 2.43 ng/mL, while the Tmax is 0.70 ± 0.11 h. The AUC0-12 is 19.81 ± 11.07 μg/mL/h. However, the absorption was poor with an absolute oral bioavailability of 0.62. Conclusion: The UPLC-MS/MS method was successfully applied in the pharmacokinetic study of TJAB1099 in rats.