Establishment of drugs for probing in vivo activity of xenobiotic transporters in humans

在本研究中，为了建立能够评估外源转运体在人体内转运活性的探针药物，我们进行了基因敲除动物的体内研究和人肾片的体外转运研究。本研究的结果如下：1) Mrp3参与抗肿瘤药物如氨甲喋呤和SN-38（伊立替康的活性形式）的正弦外排，以及氨甲喋呤的肠道吸收。2) Bcrp限制植物雌激素、丹曲林、吡唑嗪和曲安霉素的脑渗透。3)人体肾脏切片可以评估肾脏基底外侧有机阴离子转运蛋白OAT1和OAT3的贡献。体外研究表明，OAT1主要参与阿德福韦的肾脏摄取，OAT3主要参与奥美沙坦的肾脏摄取。4)为了检验探针药物的有效性，我们建立了模型探针化合物普伐他汀的PBPK模型，该模型考虑了转运体介导的膜转运过程。使用体内外推系数，口服和静脉给药后的预测血浆浓度符合观察值。综上所述，甲氨蝶呤可用于探测Mrp3的功能，阿德福韦用于探测OAT1，奥美沙坦用于探测OAT3。对于Bcrp在血脑屏障的功能，植物雌激素和丹曲lene如果用11C或13N标记进行PET分析，则可以使用。这些探针药物将用于研究药物相互作用的机制，以及由于遗传多态性导致的转运功能的个体差异。

In the present study, to establish probe drugs which allows evaluation of in vivo transport activities of xenobiotic transporters in human, in vivo studies using gene knockout animal and in vitro transport studies using human kidney slices were carried out. The findings of the present study is as follows;1) Mrp3 is involved in the sinusoidal efflux of anticancer drugs such as methotreate and SN-38 (an active form of irinotecan), and in the intestinal absorption of methotrexate.2) Bcrp limits the brain penetration of phytoestrongens, dantrolene, prazosin and triamterene.3) Human kidney slices allows evaluation of contribution of renal basolateral organic anion transporters, OAT1 and OAT3. In vitro study suggests that OAT1 mainly accounts for renal uptake of adefovir, and OAT3 for the uptake of olmesartan.4) To examine the usefulness of probe drugs, PBPK model, in which transporter-mediated membrane transport process is taken into consideration, has been established for a model probe compound, pravastatin. Using in vitro-in vivo extrapolation coefficient, the predicted plasma concentrations following oral and intravenous administration fits the observed value.In conclusion, methotrexate can be used for probing Mrp3 function, and adefovir for OAT1 and olmesartan for OAT3. As for Bcrp function at the blood brain barrier, phtytoestrogens and dantrolene can be used if they are labeled by 11C or 13N for PET analysis. These probe drugs will be used for investigating the mechanisms of drug-drug interaction, and interindividual difference in transport function due to genetic polymorphisms.