代谢
炔诺孕酮在体内被广泛代谢,主要在肝脏通过其A环的部分和完全还原转化为多种代谢物。涉及的酶主要是3α-和3β-羟基类固醇脱氢酶(HSD)以及5α-和5β-还原酶。5α-还原的代谢物,包括5α-二氢炔诺孕酮及其衍生物,似乎具有生物活性,而5β-还原的代谢物似乎无活性。炔诺孕酮及其代谢物也会广泛结合 - 大多数血浆中的代谢物是硫酸盐结合物,而大多数尿液中的代谢物是葡萄糖醛酸结合物。血浆中的主要代谢物是3α,5α-四氢炔诺孕酮的二硫酸盐结合物和3α,5β-四氢炔诺孕酮的单硫酸盐结合物,而尿液中的主要代谢物是由3α,5β-四氢炔诺孕酮的葡萄糖醛酸和/或硫酸盐结合物组成。炔诺孕酮还被观察到通过细胞色素P450酶系统进行一定程度的代谢,主要由CYP3A4以及较少程度的CYP2C19、CYP1A2和CYP2A6介导。这些反应产生的代谢物尚未被完全表征。
Norethisterone is extensively metabolized, primarily in the liver, to a number of metabolites via partial and total reduction of its A-ring. The enzymes predominantly involved are 3α- and 3β-hydroxysteroid dehydrogenase (HSD) as well as 5α- and 5β-reductase. The 5α-reduced metabolites, including 5α-dihydronorethisterone and its derivatives, appear to carry biological activity while the 5β-reduced metabolites appear inactive. Norethisterone and its metabolites are also extensively conjugated - most of the plasmatic metabolites are sulfate conjugates, while most of the urinary metabolites are glucuronide conjugates. The major metabolites in plasma are a disulfate conjugate of 3α,5α-tetrahydronorethisterone and a monosulfate conjugate of 3α,5β-tetrahydronorethisterone, while the major metabolite(s) in the urine are comprised of glucuronide and/or sulfate conjugates of 3α,5β-tetrahydronorethisterone. Norethisterone has also been observed to undergo some degree of metabolism via the cytochrome P450 enzyme system, predominantly by CYP3A4 and, to a much lesser extent, by CYP2C19, CYP1A2, and CYP2A6. The metabolites generated by these reactions have not been fully characterized.
来源:DrugBank