Effects Of Danshen On The Pharmacokinetics Of Losartan And Significance In Interaciton Between Traditional Chinese Medicine And Chemical Medicine

Traditional Chinese medicine(TCM)，which has a long history in China and otherAsian countries, has already been proven to have a certain advantage of chronic diseasetreatment that hardly leads to adverse or toxic effects and gradually taken seriously byNorth America and Europe. In the past times, most people think of TCM derived fromnatural plants, as safe and non-toxic, unlike the chemical drugs vulnerable to druginteractions. In fact, TCM contains a variety of bio-active ingredients, whose chemicalcomposition is similar with commonly used chemical drugs, thus it can play a role inphysiological regulation together through synergistic or antagonistic effects and is alsopossible to interact with any type of drug. Although most people used to paid attention todrug-drug interaction in the past years, recently, increasing number of suggest thatinteractions between TCM and chemical drugs resulted in decreased eiffcacy and toxicity,which has aroused widespread concern in the medical community.Losartan is the ifrst nonpeptide angiotensin II receptor blocker，which cancompetitively antagonize vasoconstriction resulted from angiotensin II receptor ATIsubtype, reduce peripheral vascular resistance and enable the treatment of hypertension.While losartan can be transformed into its active metabolite EXP3174mediated bycytochrome CYP450enzymes CYP3A4and CYP2C9and both losartan and its metaboliteEXP3174can be speciifcally combined with the AT1receptors, confront pharmacologicaleffects of angiotensin II and play an antihypertensive action. Danshen is an importanttraditional Chinese multiherbal formula composed of Tanshinonel IIA，Salvianolic acid Band so on，which is widely used for the treatment of cardiovascular and cerebrovasculardiseases in China. Danshen was used in conjunction with losartan in treatment ofhypertension, in order to achieve the purpose of promoting blood circulation and bloodpressure, for its effects of blood circulation, reducing blood viscosity, improving bloodvessel elasticity. However, the current research of Danshen and losartan was limited inifeld of pharmacodynamics, and few researches of interaction between Danshen andlosartan were reported. Therefore，studying the interaction of Danshen and losartan hascertain clinical signiifcance. The aim of this study is to (1) compare the pharmacokineticsof losartan and EXP3174after oral administration of single losartan and both losartan andDanshen tablet, losartan and Tanshinonel IIA, losartan and Salvianolic acid B，andinvestigate the inlfuence of Danshen tablet on the pharmacokinetics of losartan and its metabolite EXP3174;(2) detect effects of chemical compositions of Danshen (salvianolicacid B and tanshinone IIA) on the expression of CYP3A4, CYP2C9enzyme mRNA andprotein level by RT-PCR and western-blot method, and investigate the interaction relationbetween Danshen and losartan based on P450activity in cell level.A simple, rapid and reliable liquid chromatographic-tandem mass spectrometry(LC-MS) method was developed and validated for the quantiifcation of Los and EXP3174in rat plasma, which meets the current FDA criteria for bioanalytical method validation andwas successfully applied to study interactions between Danshen tablet and Los andEXP3174. The experiment was divided into single-term administration group andlong-term administration group. The long-term medication group was treated withDanshen tablets, tanshinone IIB and salvianolic acid salt for14days, and then treated withlosartan.Male Sprague-Dawley rats were randomly assigned to four groups: single losartangroup, losartan and Danshen tablet group, losartan and Tanshinonel IIA group, losartan andSalvianolic acid B group. Plasma concentrations of losartan and EXP3174weredetermined by LC-MS at designated points after drug administration, and mainpharmacokinetic parameters were estimated. The parameters (Cmax，ti/2, CL) of losartan insingle-term administration group (A) were smaller than those of both losartan and group B.The parameters (k，AUC(o-24)，AUMQ0-24))，AUC，AUMC and MRT) of losartan andEXP3174in group A were bigger than that in group B. The difference was signiifcant(p<0.05). The drug combination can reduce losartan prototype drug ti/2, CL and Vd，prolong the Tmax，suggesting that Danshen and its active ingredients can accelerate themetabolism and metabolites of losartan. But the pharmacokinetic parameters of EXP3174compared with the single drug showed no signiifcant difference，so the effects ofmetabolites is not obvious. Long-term administration group results show that: drugsadministrated in combination with losartan can reduce its T1/2，CL and Vd,suggesting thatDanshen and its active ingredients can induce losartan metabolism in rats. Compared withthe pharmacokinetic parameters of combination drug administration with EXP3174，thoseof single adminitration’s are different in that half-life is prolonged andthe apparent volumeof distribution is increased,showing that Danshen tablets have induced effect onlosartan.The results of Long-term administration were similar with the single-termadministration results.lt was found that there was signiifcant difference (p<0.05) betweenthe pharmacokinetic parameters of losartan and EXP3174(Tmax，ti/2, AUCo-24，AUCo-①，Vdand CL), which showed that Danshen tablet can induce the metabolism of losartan in vivo. Besides pharmacokinetic study of chinese-chemical combinational medication, this studyalso analyzed the effects of Chinese herbs on drug metabolizing enzyme system by usingChang liver cell as a model to investigate molecular basis of interaction of Danshen andlosartan in cell level. Expressive levels of CYP3A4，CYP2C9mRNA and protein weredetermined in Chang Liver cells treated by Tanshinonel IIA(l,10,100(iM) and Salvianolicacid B (l，10，100jiM) for48hours using RT-PCR and western-blot. Results showed:Tanshinonel IIA and Salvianolic acid B can signiifcantly induce the expression of CYP3A4and CYP2C9mRNA and protein after Chang liver cells were treated for48hours(p<0.05),and the induction effect is concentration dependent.This study exempliifed traditional Chinese medicine Danshen and chemical medicinelosartan (Los), which not only applied several tools and approaches based onmultidisciplinary including pharmacokinetics and molecular biology, but also combinedanalyses on integrity level (effects of Chinese herbs on drug metabolizing enzyme system)and molecular level (pharmacokinetic study of chinese-chemical medicine) to constructinnovative system research methods based on CYP450enzyme from molecular-cell-wholeanimal level, and predict possible interaction in drug metabolism level. Results ofpharmacokinetic study of Danshen-losartan medicine showed that Danshen preparation(Danshen tablets, tanshinone IIA injection and salvianolate injection) can accelerate drugmetabolism of losartan in rats; further research in effects of Danshen on CYP450enzymeconifrmed molecular basis of Danshen preparation inlfuencing drug metabolism of losartan,that is Danshen preparation may accelerate drug metabolism of losartan by inducingCYP3A4and CYP2C9enzyme activity. Therefore，Danshen combined with losartan inclinical treatment may exhibit potential interactions, and people should pay attention totheir medication and dosage adjustment.