Accurate determination of a novel vasodilatory ß-blocker TJ0711 using LC-MS/MS: Resolution of an isobaric metabolite interference in dog plasma.

A rapid, robust and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for bioanalysis of TJ0711, a novel vasodilatory ß-blocker in dog plasma. This assay is able to chromatographically separate TJ0711 from its isobaric metabolite as well as glucuronide conjugates. Chromatographic separation was achieved on a Welch Ultimate-XB C18 column (2.1 × 100 mm, 3 µm). The analyte and internal standard (propranolol) were extracted from plasma by liquid-liquid extraction using ethyl acetate. The mass spectrometric detection was carried out in positive ion multiple reaction monitoring mode. Good linearity was obtained over the concentration range of 0.5-500 ng/mL (r > 0.99) for TJ0711. Moreover, the method had good accuracy (RE ranging from -2.70 to -0.32%) and precision (RSD < 7.55%). TJ0711 was stable in dog plasma for at least 6 h at ambient temperature, for at least 30 days at -20°C and after three freeze-thaw cycles. This method was successfully applied to a preclinical pharmacokinetic study and the results demonstrated linear pharmacokinetics of TJ0711 over a dose range from 0.03 to 0.3 mg/kg. No significant gender differences were observed in TJ0711 plasma pharmacokinetic parameters.

Influence of dose and route of administration on the enantioselective pharmacokinetics of TJ0711 hydrochloride in rats.

The enantioselective pharmacokinetics of TJ0711 hydrochloride were studied in rats given different doses of rac-TJ0711 hydrochloride via intravenous and oral routes. R- and S-TJ0711 hydrochloride were both rapidly absorbed, and the average AUC0-∞ of R-TJ0711 hydrochloride was greater than that of S-TJ0711 hydrochloride after intragastric administration, with an R/S AUC ratio 1.11 and 1.35 for 30 and 50 mg/kg dose group, respectively. In contrast, the average AUC0-∞ of R-TJ0711 hydrochloride was smaller than that of S-TJ0711 hydrochloride after intravenous injection, with an R/S AUC ratio 0.57 and 0.73 for 10 and 20 mg/kg dose group, respectively. R-TJ0711 hydrochloride plasma half-lives were shorter than those of S-TJ0711 hydrochloride for all groups. AUC0-4h and Cmax between the two enantiomers were significantly different after oral administration of 50 mg/kg dose of the racemate, while no significant differences between the two enantiomers were found for all the pharmacokinetic parameters of the 30 mg/kg dose group. Significant differences between the two enantiomers were detected for nearly all the pharmacokinetic parameters after intravenous administration, except for the VZ of 20 mg/kg dose group. This study suggests that dose and route of administration will influence the enantioselectivity in the pharmacokinetics of TJ0711 hydrochloride in rats.

Stereoselective HPLC assay of TJ0711 enantiomers by precolumn derivatization with GITC using UV detection and its application in pharmacokinetics in rats.

This investigation describes a new precise, sensitive and accurate stereoselective RP-HPLC method for determination of the enantiomers of a novel alpha- and beta-receptor blocking agent, 1-[4-(2-methoxyethyl) phenoxy]-3-[[2-(2- methoxyphenoxy) ethyl]amino]-2-propanol (TJ0711), in rat plasma. GITC was used for precolumn derivatization of TJ0711 enantiomers. Enantiomeric resolution was achieved on a Eurospher-100 C18 column (250 mm x 4.6 mm ID, 5-mum particle size), with UV detection at 255 nm, and the mobile phase consisted of acetonitrile and water (58:42, v/v) containing 0.02% glacial acetic acid (v/v). Using the chromatographic conditions described, TJ0711 enantiomers were well resolved with mean retention time of 10.2 and 11.5 min, respectively. Linear response (r>0.999) was observed over the range of 0.125-12.5 microg/mL of TJ0711 hydrochloride enantiomers. The mean relative standard deviation (RSD%) of the results of within-day precision was < or = 10%. The proposed method was found to be suitable and accurate for the quantitative determination of TJ0711 enantiomers in rat plasma, and it can be used in pharmacokinetic studies.