School of Pharmacy, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region.
School of Pharmacy, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region.
J Pharm Biomed Anal. 2019 May 10;168:13-22. doi: 10.1016/j.jpba.2019.02.004. Epub 2019 Feb 6.
Simvastatin is known as a pro-drug, which could be hydrolyzed by esterases to its active form, simvastatin acid. Although pharmacokinetics of simvastatin and simvastatin acid have been widely studied, hydrolysis of simvastatin to simvastatin acid during blood sampling and plasma preparation has been overlooked in the previous studies, leading to underestimation of simvastatin concentration and overestimation of simvastatin acid concentration in plasma. Since both efficacy and adverse drug reaction of simvastatin are highly dependent on simvastatin and simvastatin acid concentrations in vivo, accurate assessment of the two compounds are critical in their pharmacokinetic and pharmacodynamic studies. The current study was proposed aiming to investigate the esterase mediated hydrolysis of simvastatin in human and rat blood and its impact on the pharmacokinetic study of simvastatin and simvastatin acid. Using various esterase inhibitors including potassium florid (KF), bis(4-nitrophenyl) phosphate (BNPP), and ethylenediaminetetraacetic acid (EDTA), carboxylesterase was found to be the major esterase that hydrolyzed simvastatin in rat blood, while carboxylesterase and paraoxonase were the major esterases mediating the hydrolysis of simvastatin in human blood. Further studies using human recombinant enzymes identified simvastatin as substrates of PON1, CES1b, PON3 and CES1c with Cl of 8.75, 5.77, 3.93, and 2.45 μL/min/mg protein. Therefore, inhibition treatments with 20 mM BNPP and 50 mM KF/ 10 mM EDTA were developed to efficiently prevent the hydrolysis of simvastatin during blood sampling and plasma preparation in rat/human. The subsequent pharmacokinetics of orally administered simvastatin at 8.66 mg/kg in rats found that the C and AUC of simvastatin in absence of such esterase inhibitors in the blood sampling process were only 17.04 ± 6.60% and 15.30 ± 6.76% of those in presence of the inhibitors, whereas the C and AUC of simvastatin acid were 1.60 ± 0.30 and 1.80 ± 0.22 times of that obtained in presence of the inhibitors. Nevertheless, T of simvastatin and simvastatin acid remained the same regardless of the blood sampling method. Our current study for the first time demonstrated the importance for assessment of simvastatin stability during the blood sampling and plasma preparation process, which may be applicable to therapeutic drug monitoring of not only simvastatin but also other pro-drugs/compounds sharing similar metabolic properties.
辛伐他汀被认为是前药，可被酯酶水解为其活性形式辛伐他汀酸。尽管辛伐他汀和辛伐他汀酸的药代动力学已得到广泛研究，但在以前的研究中，辛伐他汀在血液采样和血浆制备过程中向辛伐他汀酸的水解过程被忽视了，导致血浆中辛伐他汀浓度的低估和辛伐他汀酸浓度的高估。由于辛伐他汀的疗效和药物不良反应高度依赖于体内辛伐他汀和辛伐他汀酸的浓度，因此准确评估这两种化合物对于它们的药代动力学和药效学研究至关重要。本研究旨在研究人及大鼠血液中酯酶介导的辛伐他汀水解及其对辛伐他汀和辛伐他汀酸药代动力学研究的影响。使用各种酯酶抑制剂，包括氟化钾（KF）、双（4-硝基苯基）磷酸酯（BNPP）和乙二胺四乙酸（EDTA），发现羧酸酯酶是大鼠血液中水解辛伐他汀的主要酯酶，而羧酸酯酶和对氧磷酶是介导人血液中辛伐他汀水解的主要酯酶。进一步使用人重组酶的研究表明，辛伐他汀是 PON1、CES1b、PON3 和 CES1c 的底物，Cl 分别为 8.75、5.77、3.93 和 2.45μL/min/mg 蛋白。因此，开发了 20mM BNPP 和 50mM KF/10mM EDTA 的抑制处理方法，以有效防止大鼠/人血液采样和血浆制备过程中辛伐他汀的水解。在未加入酯酶抑制剂的情况下，大鼠口服 8.66mg/kg 辛伐他汀后的药代动力学研究发现，辛伐他汀的 C 和 AUC 仅为加入抑制剂时的 17.04%±6.60%和 15.30%±6.76%，而辛伐他汀酸的 C 和 AUC 则分别为加入抑制剂时的 1.60%±0.30%和 1.80%±0.22 倍。然而，辛伐他汀和辛伐他汀酸的 T 无论血液采样方法如何都保持不变。本研究首次证明了评估辛伐他汀在血液采样和血浆制备过程中稳定性的重要性，这可能适用于不仅是辛伐他汀，而且还适用于具有相似代谢特性的其他前药/化合物的治疗药物监测。
