A rapid and highly sensitive liquid chromatography-tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the determination of a novel anti-HBV compound Y101 and its metabolites M8 and M9 in human plasma. The plasma samples were deproteinated with acetonitrile after addition of Peramivir (internal standard, IS) and separated on a 40 °C ACQUITY UPLC BEH C 18 column (2.1 mm × 50 mm, 1.7 μm). The mobile phase consisted of water (containing 5 mM ammonium acetate and 0.1% formic acid) and acetonitrile (74:26, v/v) at a flow rate of 0.3 mL/min. The detection was performed on a Triple Quad 5500 tandem mass spectrometer coupled with electrospray ionization (ESI) source in positive mode. Quantification was conducted by multiple reaction monitoring (MRM) of the transitions of m / z 490.1 → 339.0 for Y101, m / z 357.2 → 105.2 for metabolite M8, m / z 373.1 → 105.1 for metabolite M9 and m / z 329.1 → 270.2 for IS, respectively. The method was validated over the calibration curve range of 1.000–1000 ng/mL for Y101, 2.000–2000 ng/mL for metabolite M8 and 0.3000–300.0 ng/mL for metabolite M9, using linear regression and 1/x 2 weighting. No matrix effect and carryover effect was observed. The intra- and inter-batch precision and accuracy of Y101, metabolite M8 and M9 were all within the acceptable criteria. This method allows a rapid and simple determination of Y101 and its metabolites M8 and M9 in human plasma. It was successfully applied in a pharmacokinetic study in human for the first time.
Bentysrepinine (Y101) is a novel phenylalanine dipeptide for the treatment of hepatitis B virus. Renal excretion played an important role in the elimination of Y101 and its metabolites, M8 and M9, in healthy Chinese subjects, although the molecular mechanisms of renal excretion and potential drug–drug interactions (DDIs) remain unclear. The present study aimed to determine the organic anion transporters (OATs) involved in the renal disposition of Y101 and to predict the potential DDI between Y101 and entecavir, the first-line agent against HBV and a substrate of OAT1/3. Pharmacokinetic studies and uptake assays using rat kidney slices, as well as hOAT1/3-HEK293 cells, were performed to evaluate potential DDI. The co-administration of probenecid (an inhibitor of OATs) significantly increased the plasma concentrations and area under the plasma concentration–time curves of M8 and M9 but not Y101, while reduced renal clearance and the cumulative urinary excretion of M8 were observed in rats. The time course of Y101 and M8 uptake via rat kidney slices was temperature-dependent. Moreover, the uptake of M8 was inhibited significantly by probenecid and benzylpenicillin, but not byp-aminohippurate or tetraethyl ammonium. M8 was found to be a substrate of hOAT3, but Y101 is not a substrate of either hOAT1 or hOAT3. Additionally, the entecavir inhibited the uptake of M8 in the hOAT3-transfected cells and rat kidney slices in vitro. Interestingly, no significant changes were observed in the pharmacokinetic parameters of Y101, M8 or entecavir, regardless of intravenous or oral co-administration of Y101 and entecavir in rats. In conclusion, M8 is a substrate of OAT3 in rats and humans. Furthermore, M8 also mediates the DDI between Y101 and entecavir in vitro, mediated by OAT3. We speculate that it would be safe to use Y101 with entecavir in clinical practice. Our results provide useful information with which to predict the DDIs between Y101 and other drugs that act as substrates of OAT3.Keywords:Y101;entecavir;renal excretion;organic anion transporters;drug-drug interaction
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