吗替麦考酚酸酯及其活性代谢物麦考酚酸的跨膜转运机制研究

Investigation on the Mechanism of Transmembrane Transport of Mycophenolate Mofetil and Its Active Metabolite Mycophenolic Acid

目的研究吗替麦考酚酸酯(mycophenolate mofetil,MMF)及其活性代谢物麦考酚酸(mycophenolic acid,MPA)的跨膜转运机制。方法建立Caco-2细胞单层模型,进行吗替麦考酚酸酯及麦考酚酸转运实验,用LC-MS/MS方法测定转运实验样品中吗替麦考酚酸酯和麦考酚酸浓度,计算表观通透系数Papp和外排率Pratio,评价药物转运及外排作用,P-糖蛋白(P-glycoprotein,P-gp)抑制剂维拉帕米用于评价P-gp在吗替麦考酚酸酯和麦考酚酸肠道吸收转运中的作用。结果麦考酚酸在10、50和100μmol·L-1的双向转运的表观通透系数Papp,ab[和Papp,ba]分别为(9.70±0.40)×106cm·s-1[(13.52±0.28)×106cm·s-1]、(9.35±0.62)×106cm·s-1[(11.38±0.59)×106cm·s-1]和(8.69±0.69)×106cm·s-1[(10.53±0.64)×106cm·s-1];外排率Pratio分别为1.39、1.22和1.22,维拉帕米明显降低了外排率。吗替麦考酚酸酯在穿过Caco-2细胞单层转运过程中大部分被水解为麦考酚酸,麦考酚酸转运的量随转运时间延长而不断增加,而吗替麦考酚酸酯转运的量随时间无明显变化。维拉帕米对吗替麦考酚酸酯转运无明显影响。结论麦考酚酸的跨膜转运受到由转运载体介导的主动转运外排作用影响,P-gp参与了麦考酚酸的跨膜转运。吗替麦考酚酸酯的跨膜转运不存在P-gp的作用,为被动转运。

OBJECTIVE To investigate the mechanism of transmembrane transport nf mycopheno｜ate mofetil （ MMF） and its active metabolite mycophenolic acid （ MPA ）. METHODS Caco-2 cell monolayer model was developed for MMF a,d MPA transporl experiment, and the LC-MS/MS method was used for the determination of MMF and MPA concentration in transport me- dium. The apparent permeability coefficient （Papp） and effiux ratio （Pratio） were calculated and used for the evaluation of the a- bility of drug transport arid drug effiux across Caco-2 eell monolayer. RESULTS The Papp of MPA in two-way transport experi- ment （Papp,ab andPapp.ba） at 10, 50 and 100 μmol·L^-1 were（9.70±0.40） ×10^6cm·s^-1[（13.52 ±0.28） ×10^6cm·s^-1,（9.35 ±0.62） ×10^6cm·s^-1[（11.38±0.59） ×10^6cm·s^-1],（8.69±0.69） ×10^6cm·s^-1[（10.53±0.64） ×10^6cm·s^-1） , respeetively. Pratio were 1. 39, 1.22 and 1.22, respectively. Pratoi of MPA was reduced by verapamil, a well- known P-glycoprotein inhibitor. MMF was mostly hydrolyzed to MPA during the transport process across the Caco-2 cell monnlay- er. The amount of MPA transported increased with time, but the amount of MMF transported changed not significantly over time and no significant eff）ct of verapamil was observed. CONCLUSION The transmembrane transport of MPA is affcted by active transport efflux mediated by transporter with P-gp involved. No effect of P-gp is found in MMF transmembrane lransport, which is passive transport.