Department of Pharmacy, University of Washington Health Sciences Center, 1959 NE Pacific Street, Seattle, WA 98195-7630, USA.
Drug Metab Dispos. 2010 Sep;38(9):1393-6. doi: 10.1124/dmd.110.033878. Epub 2010 Jun 22.
Clonidine is a centrally acting, alpha-2 adrenergic agonist used for the treatment of hypertension during pregnancy. The metabolic pathways of clonidine are poorly understood, and the quantitative contribution of specific human cytochrome P450 (P450) isoforms has not been systematically assessed. In this study, 17 cDNA-expressed P450 enzymes, in addition to pooled human liver microsomes, were evaluated for clonidine 4-hydroxylation activity in vitro. Five P450 enzymes-CYP2D6, 1A2, 3A4, 1A1, and 3A5-catalyzed measurable formation of 4-hydroxyclonidine. Selective inhibition studies in human liver microsomes confirmed that these isoforms are jointly responsible for 4-hydroxylation of clonidine in vitro, and CYP2D6 accounted for approximately two-thirds of the activity. The major role of CYP2D6 in clonidine metabolism might explain the increase in its nonrenal clearance during pregnancy.
可乐定是一种作用于中枢的α-2 肾上腺素能激动剂,用于治疗妊娠高血压。可乐定的代谢途径尚未完全阐明,特异性人细胞色素 P450(CYP450)同工酶的定量贡献也尚未系统评估。在这项研究中,评估了 17 种 cDNA 表达的 P450 酶以及人肝微粒体,以评估它们在体外对可乐定 4-羟化的活性。5 种 P450 酶(CYP2D6、1A2、3A4、1A1 和 3A5)可催化 4-羟基可乐定的生成。在人肝微粒体中的选择性抑制研究证实,这些同工酶共同负责可乐定的体外 4-羟化,CYP2D6 约占活性的三分之二。CYP2D6 在可乐定代谢中的主要作用可能解释了其在妊娠期间非肾清除率增加的原因。