Drug Interaction And Effect Mechanism Of P-gp On The Uptake Of Atorvastatin And Acipimox

Background:Atorvastatin coadministrated with acipimox is usually used for the treatment ofhyperlipidemia. The two drugs by the oral absorption, its clinical effect is closelyrelated to the degree of gastrointestinal absorption. It has been proved thatP-glycoprotein (P-gp) is closely related to drug absorption, the outer row of functionis an important factor that lead to the reduction of drug absorption.Therefore it isnecessary to figure out the influence of the two drugs uptake by P-gp. There arereports that atorvastatin is a substrate of P-gp. However the absorption mechanism ofacipimox which is on P-gp efflux in vivo or not is unkown. If atorvastatin andacipimox together compete P-gp, or inhibit the uptake, resulting in changing atpharmacokinetic interaction. And it may cause the efficacy and safety of change.Therefore, it is very necessary to clarifIy the uptake mode of acipimox which isassociated with P-gp. Further from the clinical test to explore the MDR1Exon26polymorphism of atorvastatin and acipimox together, it can clarify that thepharmacokinetic interaction will be based on P-gp to provide experiment basis.Obiective:By Caco-2cell model, to verify that atorvastatin associated with P-gp, explorethe effect of P-gp on the absorption of acipimox and pharmacokinetic interactionstudy of atorvastatin coadministrated with acipimox. Then study MDR1Exon26polymorphism on the pharmacokinetics interaction of the two drugs in healthyChinese volunteers, in order to provide the basis information for the clinicalapplication.Methods:1. Establish and inspect the characteristics of Caco-2cell monolayer model；2. Explore time and drug concentration and PH value how affectd Caco-2cellson the uptake of atorvastatin or acipimox, through transportation of drug on Caco-2cells monolayer model, confirm mechanism of atorvastatin and acipimox which istransported by P-gp or not; 3.17subjects were given atorvastatin20mg and acipimox500mg,0-72h seriesblood were collected. The samples were detectded by LC-MS-MS and HPLC,respectively. DAS2.1software were used to calculate the pharmacokinetic paramet-ers;4. Genotypes of MDR1C3435T for blank blood samples were determined by thePCR-RFLP assay, on the basis of MDR1Exon26poly-morphism, contraste andanalys atorvastatin coadministrated with acipimox. pharmacokinetic characteristics inChinese healthy volunteers with by statistical method.Results:1. Caco-2cells grew well with clear border after been cultured on transwellplates. Value TEER increase with the length of the incubation time,which is500-600Ω cm2after22days. Alkaline phosphatase was undetected on third day, till21st daythe energy ratio (AP/BL) of alkaline phosphatase value is more than four times, whenhad an obvious polarization phenomenon.These indicators can meet integrity andpolarity of Caco-2cell monolayer mode. It was good for the following experimentmodel in vitro.2. In the Caco-2cell model, uptake of atorvastatin and acipimox was associatedwith time and the respective drug concentration, but PH of Hanks has no effect on it.The absorption of atorvastatin apparent permeability PappAP-BLis2.58×10-7cm·sec-,verapamil of P-pg inhibitor to atorvastatin, PappAP-BLvalue increased significantly,the apparent permeability PDR dropped from2.65to1.19, the difference wasstatistically significant. The apparent permeability(PDR) of acipimox is1.27,verapamil with defferent concentration group (20,40,60m) to acipimox, While thePappAP-BLand PDR had no significant change, there was no statistically significantdifference. It prompted atorvastatin was mediated by P-gp transporters. However, theacipimox wasnt transported by P-gp3. After administration of atorvastatin and acipimox, the main pharmacokineticparameters for atorvastatin were as following: AUC0-t(47.86±18.45) g/L·h, AUC0-∞(49.11±18.55) g/L·h, Cmax(9.11±4.55) g/L, tmax(0.52±0.27)h, the absorb feathers ofdrug is quickly and completely. The distribution is wildly, Vz/F(7130.257±4118.035)L, the elimination is slow, t1/2(10.29±2.08)h. The main pharmacokinetic parameters for acipimox were as following: AUC0-t(21.89±5.46)mg/L·h, AUC0-∞(22.14±5.52)mg/L·h, Cmax(6.16±1.76)mg/L, tmax(1.54±0.55)h, Vz/F(51.926±15.420)L，t1/2(1.50±0.12)h, CLz/F (24.038±6.500)L/h. Absorb of acipimoxis quickly, mainly distributed in extracellular fluid, besides eliminated completely.4.17subjects MDR1gene Exon26classification results showed that wild type3435CC have five, mutant heterozygote CT,3435homozygous mutant3435TT hassix. The occurrence rate is not concordant with the reports.5. It has an impact on the absorption characteristics of atorvastatin. AUC0-∞is60.83,47.5,37.4g/L·hwith MDR1CC, CT, TT of voluteers,AUC0-tis61.918,48.56,38.99g/L·h, respectivly. There are significantly differences between CC and TT.6. There are no significantly differences among the pharmacokinetics parametersof acipimox which included Cmax,Tmax, AUC0-t, AUC0-∞, CL, Vdand t1/2with defferentgenetype(CC, CT, TT group).Conclusion:The transport experiment of drugs comfirmed that atorvastatin was mediated byP-gp transporters. However, the acipimox wasnt transported by P-gp which is mainlyabsorded by simple diffusion. The uptake charateristics of atorvastatin and acipimoxis not affected by P-gp after atorvastatin coadministrated with acipimox in vitro.Pharmacokinetic and genotyping research suggested MDR1gene Exon26mutationonly has an impact on the absorption characteristics of atorvastatin. It indicated thatatorvastatin and acipimox may not exist uptake interaction on P-gp.