Dược Động Học :
▧ Absorption :
Following oral administration, the relative bioavailability of desogestrel, as measured by serum levels of etonogestrel, is approximately 84%. The absolute oral bioavailability is about 76%.
▧ Protein binding :
98.3%
▧ Metabolism :
Desogestrel is rapidly and completely metabolized by hydroxylation in the intestinal mucosa and on first pass through the liver. It is primarily metabolized to 3α-hydroxydesogestrel with small amounts of 3β-hydroxydesogestrel being formed. Both of these metabolites are then rapidly oxidized to its active metabolite, etonogestrel (3-ketodesogestrel). Other metabolites (e.g. 2-hydroxydesogestrel) with no pharmacologic action have also been identified. Desogestrel and some of its metabolites (e.g. 3β-hydroxydesogestrel, 15β-hydroxydesogestrel) may also undergo glucuronide and sulfate conjugation. Early in vitro studies demonstrated that CYP2C9 and possibly CYP2C19 were involved in the conversion of desogestrel to 3α-hydroxydesogestrel and 3β-hydroxydesogestrel (PMID 9864282); however, later clinical studies conducted in humans refuted this result (PMID 15963096). The latter study indicates that CYP3A4 plays an important role in metabolizing etonogestrel. Thus, strong CYP3A4 inhibitors or inducers could result in increased side effects or therapeutic failure, respectively.
▧ Half Life :
27.8±7.2 hours