The determination of 2-(2-hydroxypropanamido) benzoic acid enantiomers and their corresponding prodrugs in rat plasma by UHPLC-MS/MS and application to comparative pharmacokinetic study after a single oral dose

A simple and sensitive UHPLC-MS/MS method was developed and validated to determine the pharmacokinetic profile of 2-(2-hydroxypropanamido) benzoic acid (HPABA) enantiomers and their prodrugs in rat plasma. Separation was performed on a Thermo Syncronis C18 column (50 mm × 2.1 mm, 1.7 μm; Thermo, USA), which was protected by a high pressure column prefilter (2 μm) at a flow rate of 0.4 ml/min. Liquid-liquid extraction with ethyl acetate was used to process plasma samples. The separation of two enantiomers, prodrugs of (R)-/(S)-HPABA and internal standard was obtained within a cycle time of 4.5 min. The lower limit of quantification of (R)-/(S)-HPABA and prodrugs of (R)-/(S)-HPABA in plasma were 0.01 μg/ml and 0.2 μg/ml, respectively. (S)-HPABA showed significantly higher AUC, Cmax and a longer t1/2 than (R)-HPABA, indicating higher bioavailability of the (S)-HPABA. Additionally, inversion between HPABA enantiomers was not observed in rats. (R)-/(S)-HPABA showed higher Cmax and AUC than those of their prodrugs. However, the values of t1/2 of prodrugs were higher than those of (R)-/(S)-HPABA. Furthermore, the higher Vz values of prodrugs might improve the targeting of (R)-/(S)-HPABA in rat tissues.