Study On Pharmacokinetic Of Compound Timosaponin B-II In Rats

Compound Timosaponin B-II, a kind of steroidal saponins that contains two sugar chains with high hydrophilicity, is isolated from the rhizoma of Anemarrhena asphodeloides Bge (Liliaceae), a traditional Chinese medicine named as"zhimu". It has been proved to have an effective action on anti-cerebral ischemia through expending blood vessels, increasing cerebral blood flow, eliminating free radicals, inhibiting platelet aggregation and promoting proliferation of hippocampus neurocyte in rat fetus. It also can improve learning and memory ability of dementia mice model. The satisfied pharmacological activity and safety make it to be a promising anti-dementia new drug candidate. The purpose of this study is to investigate the pharmacokinetic property of Timosaponin B-II and supplied the important reference material for the development of safe, effective and reasonable treatment in clinic. This study would be very useful for the further research of Timosaponin B-II about the pharmacology mechanism.The contents of this study are including: 1) it employed a rapid, sensitive and accurate high performance liquid chromatography (HPLC) tandem mass spectrometric (MS) method for determination of Timosaponin B-II in rat plasma, and the method was validated. 2) Pharmacokinetic parameters and concentration-time curve of original drug in two rats (SD and Wistar), including the dependence of dose to pharmacokinetic parameters. 3) Influence of the food to Pharmacokinetic pharmaeters.4) the distribution of drug in dosing site and critical organs or tissues and the changes over the observation time. 5) The excretion of the drug through urine, feces and bile. Results of the study were: 1) The linear calibration curves were obtained in the concentration range of 5-2000 ng/mL. The lower limit of quantification (LLOQ) was 5 ng/mL. The intra- and inter-batch precisions at three quality control (QC) levels were within 10.3 %, respectively.The run time for each sample was 3.0 min. The accuracy of the assay at the three QC levels were from -3.7 % to 7.5 %,the Extraction Recovery were 91 %,112 %,107 % at the three QC levels, the results were satisfied with the requirements of pharmacokinetic research. 2) Rat plasma level after dosing displayed great individual difference. The concentration-time curve of three dosage showed irregular profile different from the classic concentration-time curve after oral administration. The more dose the more obviously double-peak phenomenon. The absolute bioavailability of Timosaponin B-II after oral administration was very low,it was 0.11±0.09 % in SD rats.The feature of Wistar's PK .was similar with SD's. 3) There are both of double peak in fasting group and non-fasting group, the first absorption peak of fasting significantly higher than non-fasting's. The results showed that chyme increased Timosaponin B-II in the gastrointestinal tract absorption, but because of the presence of food, absorption feature is more irregular.4) After oral medium dose Timosaponin B-II solution, the data of the distribution study showed the major of intact drug were distributed in stomach, intestine and intestine contents.In the brain,there were very a few of drug. 5) The accumulated excreted form bile within 24 h after administration was 2.54±1.59 %,The total excreted form urine and feces were 0.0149±0.0089 %,it excreted form the urine was 0.0144±0.0082 % within 96h.There was not detectable concentration of Timosaponin B-II after 24 h. All of these may suggest that it would be a lot of metabolites in bile or/and feces.We would conclude from the study of results that Rat plasma level after dosing displayes great individual difference, and the bioavailability of Timosaponin B-II after oral administration was very low. Chyme increased Timosaponin B-II in the gastrointestinal tract absorption, but because of the presence of food, absorption feature is more irregular. After oral administration Timosaponin B-II, the data of the distribution study shows the major of intact drug are distributed in gastrointestinal tract,and a few of intact drug are found in other tissues or organs. The rate of distribution is very fast.There are a few inact drug in brain, and no changes in time phase.