Goldman Jennifer L, Koen Yakov M, Rogers Steven A, Li Kelin, Leeder James S, Hanzlik Robert P
Divisions of Clinical Pharmacology, Toxicology, and Therapeutic Innovation, Children's Mercy Hospital, University of Missouri, Kansas City, Missouri (J.L.G., J.S.L.); Department of Medicinal Chemistry, University of Kansas School of Pharmacy, Lawrence, Kansas (Y.M.K., R.P.H.); Baker & McKenzie LLP, Dallas, Texas (S.A.R.); and Center for Integrative Chemical Biology and Drug Discovery, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina (K.L.)
Divisions of Clinical Pharmacology, Toxicology, and Therapeutic Innovation, Children's Mercy Hospital, University of Missouri, Kansas City, Missouri (J.L.G., J.S.L.); Department of Medicinal Chemistry, University of Kansas School of Pharmacy, Lawrence, Kansas (Y.M.K., R.P.H.); Baker & McKenzie LLP, Dallas, Texas (S.A.R.); and Center for Integrative Chemical Biology and Drug Discovery, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina (K.L.).
Drug Metab Dispos. 2016 Oct;44(10):1603-7. doi: 10.1124/dmd.116.072041. Epub 2016 Jul 25.
The formation of drug-protein adducts via metabolic activation and covalent binding may stimulate an immune response or may result in direct cell toxicity. Protein covalent binding is a potentially pivotal step in the development of idiosyncratic adverse drug reactions (IADRs). Trimethoprim (TMP)-sulfamethoxazole (SMX) is a combination antibiotic that commonly causes IADRs. Recent data suggest that the contribution of the TMP component of TMP-SMX to IADRs may be underappreciated. We previously demonstrated that TMP is bioactivated to chemically reactive intermediates that can be trapped in vitro by N-acetyl cysteine (NAC), and we have detected TMP-NAC adducts (i.e., mercapturic acids) in the urine of patients taking TMP-SMX. However, the occurrence and extent of TMP covalent binding to proteins was unknown. To determine the ability of TMP to form protein adducts, we incubated [(14)C]TMP with human liver microsomes in the presence and absence of NADPH. We observed protein covalent binding that was NADPH dependent and increased with incubation time and concentration of both protein and TMP. The estimated covalent binding was 0.8 nmol Eq TMP/mg protein, which is comparable to the level of covalent binding for several other drugs that have been associated with covalent binding-induced toxicity and/or IADRs. NAC and selective inhibitors of CYP2B6 and CYP3A4 significantly reduced TMP covalent binding. These results demonstrate for the first time that TMP bioactivation can lead directly to protein adduct formation, suggesting that TMP has been overlooked as a potential contributor of TMP-SMX IADRs.
通过代谢活化和共价结合形成药物 - 蛋白质加合物可能会刺激免疫反应，或导致直接的细胞毒性。蛋白质共价结合是特发性药物不良反应（IADR）发生过程中一个潜在的关键步骤。甲氧苄啶（TMP）-磺胺甲恶唑（SMX）是一种常用的联合抗生素，常引起IADR。最近的数据表明，TMP-SMX中TMP成分对IADR的作用可能未得到充分认识。我们之前证明，TMP可被生物活化成化学反应性中间体，这些中间体在体外可被N-乙酰半胱氨酸（NAC）捕获，并且我们在服用TMP-SMX的患者尿液中检测到了TMP-NAC加合物（即硫醚氨酸）。然而，TMP与蛋白质共价结合的发生情况和程度尚不清楚。为了确定TMP形成蛋白质加合物的能力，我们在有和没有NADPH的情况下，将[¹⁴C]TMP与人肝微粒体一起孵育。我们观察到蛋白质共价结合是NADPH依赖性的，并且随着孵育时间以及蛋白质和TMP浓度的增加而增加。估计的共价结合为0.8 nmol 当量TMP/mg蛋白质，这与其他几种与共价结合诱导的毒性和/或IADR相关的药物的共价结合水平相当。NAC以及CYP2B6和CYP3A4的选择性抑制剂显著降低了TMP的共价结合。这些结果首次证明TMP生物活化可直接导致蛋白质加合物的形成，表明TMP作为TMP-SMX所致IADR的一个潜在因素一直被忽视。
