Pharmacokinetics of gastrodin from compound Tianma granule in rats

To study the influence of the compatibility of ophiopogonis tuber and Chinese magnoliavine fruit with gastrodia rhizome on the pharmacokinetics of gastrodin in rat, three dosages of compound Tianma granule extract (equivalent to gastrodin 50, 100, 200 mg·kg⁻¹) and one dosage of Tianma extract (equivalent to gastrodin 100 mg·kg⁻¹) were administered to rats by intragastric administration separately.  Plasma samples were collected at different times and treated with methanol and acetonitrile to precipitate protein.  The contents of gastrodin in plasma were determined by HPLC method.  The mean plasma concentration-time curves of different medication administration teams were processed with WinNonlin 5.2.1 pharmacokinetic software.  The pharmacokinetic parameters of different medication administration teams were analyzed with SPSS statistics 17.0 software.  The results indicated that the in vivo kinetic process of gastrodin was fitted to first-order absorption un-compartment model at low, middle dosages and zero-order absorption un-compartment model at high dosage of compound Tianma granule extract.  By comparison with the pharmacokinetic parameters of gastrodin (100 mg·kg⁻¹) in Tianma extract, the significant decrease for C_max and significant increase for MRT_0−∞ in compound Tianma granule extract indicated that the compatibility of ophiopogonis tuber and Chinese magnoliavine fruit with Gastrodia rhizome can delay the absorption, reduce the elimination rate and prolong the action time of gastrodin in vivo.