Plasma Stability-Dependent Circulation of Acyl Glucuronide Metabolites in Humans: How Circulating Metabolite Profiles of Muraglitazar and Peliglitazar Can Lead to Misleading Risk Assessment
作者:Donglu Zhang、Nirmala Raghavan、Lifei Wang、Yongjun Xue、Mary Obermeier、Stephanie Chen、Shiwei Tao、Hao Zhang、Peter T. Cheng、Wenying Li、Ragu Ramanathan、Zheng Yang、W. Griffith Humphreys
DOI:10.1124/dmd.110.035048
日期:2011.1
Muraglitazar and peliglitazar, two structural analogs differing by a methyl group, are dual peroxisome proliferator-activated receptor-α/γ activators. Both compounds were extensively metabolized in humans through acyl glucuronidation to form 1- O -β-acyl glucuronide (AG) metabolites as the major drug-related components in bile, representing at least 15 to 16% of the dose after oral administration. Peliglitazar AG was the major circulating metabolite, whereas muraglitazar AG was a very minor circulating metabolite in humans. Peliglitazar AG circulated at lower concentrations in animal species than in humans. Both compounds had a similar glucuronidation rate in UDP-glucuronic acid-fortified human liver microsomal incubations and a similar metabolism rate in human hepatocytes. Muraglitazar AG and peliglitazar AG were chemically synthesized and found to be similarly oxidized through hydroxylation and O -demethylation in NADPH-fortified human liver microsomal incubations. Peliglitazar AG had a greater stability than muraglitazar AG in incubations in buffer, rat, or human plasma (pH 7.4). Incubations of muraglitazar AG or peliglitazar AG in plasma produced more aglycon than acyl migration products compared with incubations in the buffer. These data suggested that the difference in plasma stability, not differences in intrinsic formation, direct excretion, or further oxidation of muraglitazar AG or peliglitazar AG, contributed to the observed difference in the circulation of these AG metabolites in humans. The study demonstrated the difficulty in doing risk assessment based on metabolite exposure in plasma because the more reactive muraglitazar AG would not have triggered a threshold of concern based on the recent U.S. Food and Drug Administration guidance on Metabolites in Safety Testing, whereas the more stable peliglitazar AG would have.
Muraglitazar 和 peliglitazar 是两种结构相似的显著不同于一个甲基组的化合物,都是双重的过氧化物增殖物活化受体-α/γ 激活剂。这两种化合物在人体内经过酰基葡萄糖醛酸化被广泛代谢,形成 1-O-β-酰基葡萄糖醛酸(AG)代谢物,作为胆汁中主要的药物相关成分,口服给药后至少占剂量的 15% 到 16%。在体内,peliglitazar AG 是主要的循环代谢物,而 muraglitazar AG 在人体内则是非常微量的循环代谢物。与人类相比,peliglitazar AG 在动物种群中以较低浓度循环。这两种化合物在 UDP-葡萄糖醛酸强化的人肝微粒体培养中具有相似的葡萄糖醛酸化速率,而在人体肝细胞中的代谢速率也相似。Muraglitazar AG 和 peligrositazar AG 经过化学合成,被发现通过氢氧化和 O-去甲基化在 NADPH 强化的人肝微粒体培养中有相似的氧化反应。相比于 muraglitazar AG,peliglitazar AG 在缓冲液、鼠或人类血浆(pH 7.4)的培养中表现出更大的稳定性。与在缓冲液中的培养相比,muraglitazar AG 或 peliglitazar AG 在血浆中的培养中产生了更多的无糖部分而不是酰基迁移产物。这些数据表明,血浆稳定性之间的差异,而不是 muraglitazar AG 或 peliglitazar AG 内在形成、直接排泄或进一步氧化的差异,导致了在人体中观察到的这两种 AG 代谢物循环的差异。这项研究表明,基于血浆中代谢物暴露进行风险评估的困难,因为反应性更强的 muraglitazar AG 不会根据美国食品和药物管理局关于安全性测试中代谢物的最新指导触发关注的阈值,而更稳定的 peliglitazar AG 则会。