Dept. Safety and Exploratory Pharmacology, Safety Assessment and Laboratory Animal Resources, MRL, Merck &Co., West Point, PA, USA.
Dept. Preclinical ADME, Pharmacokinetics, Pharmacodynamics and Drug Metabolism, MRL, Merck &Co., West Point, PA, USA.
Sci Rep. 2017 Mar 22;7:44820. doi: 10.1038/srep44820.
Severe bradycardia/bradyarrhythmia following coadministration of the HCV-NS5B prodrug sofosbuvir with amiodarone was recently reported. Our previous preclinical in vivo experiments demonstrated that only certain HCV-NS5B prodrugs elicit bradycardia when combined with amiodarone. In this study, we evaluate the impact of HCV-NS5B prodrug phosphoramidate diastereochemistry (D-/L-alanine, R-/S-phosphoryl) in vitro and in vivo. Co-applied with amiodarone, L-ala,S prodrugs increased beating rate and decreased beat amplitude in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), but D-ala,R produgs, including MK-3682, did not. Stereochemical selectivity on emerging bradycardia was confirmed in vivo. Diastereomer pairs entered cells equally well, and there was no difference in intracellular accumulation of L-ala,S metabolites ± amiodarone, but no D-ala,R metabolites were detected. Cathepsin A (CatA) inhibitors attenuated L-ala,S prodrug metabolite formation, yet exacerbated L-ala,S + amiodarone effects, implicating the prodrugs in these effects. Experiments indicate that pharmacological effects and metabolic conversion to UTP analog are L-ala,S prodrug-dependent in cardiomyocytes.
近期有报道称，HCV-NS5B 前药索磷布韦与胺碘酮联合使用后会导致严重心动过缓/心律失常。我们之前的临床前体内实验表明，只有某些 HCV-NS5B 前药与胺碘酮联合使用时才会引起心动过缓。在这项研究中，我们评估了 HCV-NS5B 前药磷酰胺立体化学（D-/L-丙氨酸、R-/S-磷酸基）在体外和体内的影响。与胺碘酮共同应用时，L-ala，S 前药可增加人诱导多能干细胞衍生心肌细胞（hiPSC-CMs）的搏动率并降低搏动幅度，但 D-ala，R 前药（包括 MK-3682）则没有。体内确认了对新出现心动过缓的立体化学选择性。非对映异构体对细胞的进入能力相同，且 L-ala，S 代谢物±胺碘酮的细胞内积累无差异，但未检测到 D-ala，R 代谢物。组织蛋白酶 A（CatA）抑制剂可减弱 L-ala，S 前药代谢产物的形成，但会加剧 L-ala，S+胺碘酮的作用，表明这些作用与前药有关。实验表明，在心肌细胞中，药理作用和代谢转化为 UTP 类似物均依赖于 L-ala，S 前药。
