[Pharmacokinetic comparison between Tanreqing Capsules Substitute and Tanreqing Capsules in rats by LC-MS/MS]

Due to the limited resource of bear bile powder, the major raw material of Tanreqing Capsules(TRQ), cultured bear bile powder is used as a replacement to develop the Tanreqing Capsules Substitute(TRQS). An LC-MS/MS method was established in this study for simultaneous quantitation of 8 compounds from TRQS in rat plasma: tauroursodeoxycholic acid(TUDCA), taurocheno-deoxycholic acid(TCDCA), ursodeoxycholic acid(UDCA), chenodeoxycholic acid(CDCA), ferulic acid, wogonoside, baicalin, and forsythoside A. Thereby, the pharmacokinetic behaviors of TRQ and TRQS were evaluated. Concentration of endogenous compounds TUDCA, TCDCA, UDCA, and CDCA was determined with the stable isotope surrogate analytes: D4-TUDCA, D4-TCDCA, D4-UDCA, and D4-CDCA. Plasma samples were extracted by acetonitrile-induced protein precipitation. The LC conditions are as follows: Waters BEH C_(18) column(2.1 mm×100 mm, 1.7 μm), mobile phase of 10 mmol·L~(-1) ammonium formate aqueous solution(containing 0.01% formic acid) and acetonitrile-methanol mixture(1∶5). MS conditions are as below: multiple reaction monitoring(MRM), ESI~(+/-). Concentration of UDCA, CDCA, TUDCA, and TCDCA was corrected with a response factor, which is the ratio between the responses recorded for the surrogate and the authentic analyte at the equal concentration. Each of the plasma components showed good linearity(r > 0.995 1). Accuracy and precision met the criteria(inter-day RSD<7.0%, RE 89.98%-112.0%; intra-day RSD<12%, RE 90.41%-111.2%). The recovery was 64.83%-119.9% and matrix effect was 87.15%-113.8%. The validated method was applied for pharmacokinetic study of TRQS and TRQ(po, 0.94 g·kg~(-1)). There was no significant difference in C_(max) and AUC_(0-24 h) of baicalin, UDCA, TUDCA, and TCDCA between the two groups, indicating similar pharmacokinetic behaviors between TRQS and TRQ in rats.