代谢
甲巯咪唑被肝脏快速且广泛地代谢,主要通过CYP450和FMO酶系统。已经鉴定出多种代谢物,尽管负责它们形成的特定酶同种物并不完全清楚。甲巯咪唑的第一个代谢物之一,3-甲基-2-硫代海因,可能有助于抗甲状腺活性 - 在大鼠中已经证实了其抗甲状腺活性,这可以解释尽管甲巯咪唑的半衰期相对较短,但给药后碘化抑制的持续时间延长。已经调查了许多代谢物作为甲巯咪唑诱导肝毒性的罪魁祸首。乙二醛和N-甲基硫脲都具有已建立的细胞毒性,并且是甲巯咪唑的环氧化中间体的已知代谢产物。认为甲巯咪唑的亚磺酸和磺酸衍生物是导致肝毒性的最终有毒物质,尽管它们的来源不清楚 - 它们可能源于甲巯咪唑通过FMO的直接氧化,或者是在代谢过程中进一步下游的N-甲基硫脲的氧化。
Methimazole is rapidly and extensively metabolized by the liver, mainly via the CYP450 and FMO enzyme systems. Several metabolites have been identified, though the specific enzyme isoforms responsible for their formation are not entirely clear. One of the first methimazole metabolites identified, 3-methyl-2-thiohydantoin, may contribute to antithyroid activity - its antithyroid activity has been demonstrated in rats and may explain the prolonged duration of iodination inhibition following administration despite methimazole's relatively short half-life. A number of metabolites have been investigated as being the culprits behind methimazole-induced hepatotoxicity. Both glyoxal and N-methylthiourea have established cytotoxicity and are known metabolic products of methimazole's dihydrodiol intermediate. Sulfenic and sulfinic acid derivatives of methimazole are thought to be the ultimate toxicants responsible for hepatotoxicity, though their origin is unclear - they may arise from direct oxidation of methimazole via FMO, or from oxidation of N-methylthiourea further downstream in the metabolic process.
来源:DrugBank