代谢
生物转化在莫索尼啶的作用中并不重要,大约10-20%的莫索尼啶会经历氧化反应,形成主要的4,5-脱氢莫索尼啶代谢物和一个通过imidazoline环开环的胍衍生物。这些4,5-脱氢莫索尼啶和胍代谢物的抗高血压效果仅分别为莫索尼啶的1/10和1/100。莫索尼啶上的甲基组(嘧啶环)或imidazole环上的氧化会导致羟基甲基莫索尼啶代谢物或羟基莫索尼啶代谢物的形成。羟基莫索尼啶代谢物可以进一步氧化成二羟基代谢物,或者失水形成脱氢莫索尼啶代谢物,后者本身可以进一步氧化形成N-氧化物。除了这些一期代谢物外,莫索尼啶的二相代谢也很明显,存在一种缺失氯的半胱氨酸结合代谢物。然而,在人类尿样中高水平的脱氢莫索尼啶代谢物的存在表明,从羟基代谢物到脱氢莫索尼啶代谢物的脱氢反应是人类主要的代谢途径。负责莫索尼啶在人类中代谢的细胞色素P450尚未确定。最终,在不同的生物尿液排泄样本中,母体莫索尼啶化合物是最丰富的成分,这证实了代谢在人类中清除莫索尼啶的作用只是适度的。
Biotransformation is unimportant with 10-20% of moxonidine undergoing oxidation reactions to the primary 4,5-dehydromoxonidine metabolite and a guanidine derivative by opening of the imidazoline ring. The antihypertensive effects of these 4,5-dehydromoxonidine and guanidine metabolites are only 1/10 and 1/100 the effect of moxonidine. Oxidation on either the methyl group (pyrimidine ring) or on the imidazole ring of moxonidine results in the formation of the hydroxylmethyl moxonidine metabolite or the hydroxy moxonidine metabolite. The hydroxy moxonidine metabolite can be further oxidized to the dihydroxy metabolite or it can lose water to form the dehydrogenated moxonidine metabolite, which itself can be further oxidized to form an N-oxide. Aside from these Phase I metabolites, Phase II metabolism of moxonidine is also evident with the presence of a cysteine conjugate metabolite minus chlorine. Nevertheless, the identification of the hydroxy moxonidine metabolite with a high level of dehydrogenated moxonidine metabolite in human urine samples suggests that dehydrogenation from the hydroxy metabolite to the dehydrogenated moxonidine metabolite represents the primary metabolic pathway in humans. The cytochromes P450 responsible for the metabolism of moxonidine in humans have not yet been determined. Ultimately, the parent moxonidine compound was observed to be the most abundant component in different biological matrices of urinary excretion samples, verifying that metabolism only plays a modest role in the clearance of moxonidine in humans.
来源:DrugBank