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The role of CYP2C in the in vitro bioactivation of the contraceptive steroid desogestrel.

Abstract

Desogestrel is a 3-deoxo progestogenic steroid that requires bioactivation to 3-ketodesogestrel. In these studies we have attempted to define the pathway of 3-ketodesogestrel formation and characterise the enzymes responsible for this biotransformation in vitro. Initial studies using deuterated desogestrel confirmed that desogestrel is metabolised by human liver microsomes via 3alpha-hydroxy and 3beta-hydroxydesogestrel to 3-ketodesogestrel. Metabolites were analysed by radiometric high-performance liquid chromatography and were identified by liquid chromatography-mass spectrometry and by cochromatography with authentic standards. Desogestrel was metabolised by microsomes from lymphoblasts containing cDNA-expressed CYP2C9 and CYP2C19 to 3alpha-hydroxydesogestrel with small amounts of 3beta-hydroxydesogestrel also being observed. The Km value for 3alpha-hydroxylation by CYP2C9 cell line microsomes was 6.5 microM and the corresponding Vmax value was 1269 pmole. mg-1. min-1. Sulfaphenazole potently inhibited 3alpha-hydroxydesogestrel formation by CYP2C9 microsomes with a Ki value of 0.91 microM. There was a significant negative correlation between 3-ketodesogestrel and CYP3A4 content/activity in a panel of human livers suggesting that the further metabolism of 3-ketodesogestrel is mediated by CYP3A4. Sulfaphenazole partially inhibited 3alpha-hydroxydesogestrel and 3-ketodesogestrel formation in human liver microsomes indicating a possible in vivo role for CYP2C9. In addition, when sulfaphenazole was combined with S-mephenytoin, further inhibition of 3alpha-hydroxydesogestrel formation was observed suggesting a possible role for CYP2C19. This was confirmed in incubations with inhibitory antibodies. Whereas an anti-CYP2C9/2C19 antibody completely abolished desogestrel metabolism, anti-CYP3A4 and anti-CYP2E1 were not inhibitory. We conclude that CYP2C9 and possibly CYP2C19 and important isoforms catalysing the initial hydroxylation of desogestrel.

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  • Authors+Show Affiliations

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    Department of Pharmacology and Therapeutics, New Medical Building, Liverpool, L69 3GE, United Kingdom.

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    MeSH

    Aryl Hydrocarbon Hydroxylases
    Biotransformation
    Cell Line
    Contraceptives, Oral, Synthetic
    Cytochrome P-450 CYP2C19
    Cytochrome P-450 CYP2C9
    Cytochrome P-450 CYP3A
    Cytochrome P-450 Enzyme Inhibitors
    Cytochrome P-450 Enzyme System
    Desogestrel
    Enzyme Inhibitors
    Humans
    Hydroxylation
    Microsomes, Liver
    Mixed Function Oxygenases
    Progesterone Congeners
    Steroid 16-alpha-Hydroxylase
    Steroid Hydroxylases

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    9864282

    Citation

    Gentile, D M., et al. "The Role of CYP2C in the in Vitro Bioactivation of the Contraceptive Steroid Desogestrel." The Journal of Pharmacology and Experimental Therapeutics, vol. 287, no. 3, 1998, pp. 975-82.
    Gentile DM, Verhoeven CH, Shimada T, et al. The role of CYP2C in the in vitro bioactivation of the contraceptive steroid desogestrel. J Pharmacol Exp Ther. 1998;287(3):975-82.
    Gentile, D. M., Verhoeven, C. H., Shimada, T., & Back, D. J. (1998). The role of CYP2C in the in vitro bioactivation of the contraceptive steroid desogestrel. The Journal of Pharmacology and Experimental Therapeutics, 287(3), pp. 975-82.
    Gentile DM, et al. The Role of CYP2C in the in Vitro Bioactivation of the Contraceptive Steroid Desogestrel. J Pharmacol Exp Ther. 1998;287(3):975-82. PubMed PMID: 9864282.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - The role of CYP2C in the in vitro bioactivation of the contraceptive steroid desogestrel. AU - Gentile,D M, AU - Verhoeven,C H, AU - Shimada,T, AU - Back,D J, PY - 1998/12/24/pubmed PY - 1998/12/24/medline PY - 1998/12/24/entrez KW - Biology KW - Clinical Research KW - Contraception KW - Contraceptive Agents KW - Contraceptive Agents, Female KW - Contraceptive Agents, Progestin KW - Desogestrel KW - Enzymes KW - Enzymes And Enzyme Inhibitors KW - Family Planning KW - In Vitro KW - Physiology KW - Research Methodology KW - Research Report SP - 975 EP - 82 JF - The Journal of pharmacology and experimental therapeutics JO - J. Pharmacol. Exp. Ther. VL - 287 IS - 3 N2 - Desogestrel is a 3-deoxo progestogenic steroid that requires bioactivation to 3-ketodesogestrel. In these studies we have attempted to define the pathway of 3-ketodesogestrel formation and characterise the enzymes responsible for this biotransformation in vitro. Initial studies using deuterated desogestrel confirmed that desogestrel is metabolised by human liver microsomes via 3alpha-hydroxy and 3beta-hydroxydesogestrel to 3-ketodesogestrel. Metabolites were analysed by radiometric high-performance liquid chromatography and were identified by liquid chromatography-mass spectrometry and by cochromatography with authentic standards. Desogestrel was metabolised by microsomes from lymphoblasts containing cDNA-expressed CYP2C9 and CYP2C19 to 3alpha-hydroxydesogestrel with small amounts of 3beta-hydroxydesogestrel also being observed. The Km value for 3alpha-hydroxylation by CYP2C9 cell line microsomes was 6.5 microM and the corresponding Vmax value was 1269 pmole. mg-1. min-1. Sulfaphenazole potently inhibited 3alpha-hydroxydesogestrel formation by CYP2C9 microsomes with a Ki value of 0.91 microM. There was a significant negative correlation between 3-ketodesogestrel and CYP3A4 content/activity in a panel of human livers suggesting that the further metabolism of 3-ketodesogestrel is mediated by CYP3A4. Sulfaphenazole partially inhibited 3alpha-hydroxydesogestrel and 3-ketodesogestrel formation in human liver microsomes indicating a possible in vivo role for CYP2C9. In addition, when sulfaphenazole was combined with S-mephenytoin, further inhibition of 3alpha-hydroxydesogestrel formation was observed suggesting a possible role for CYP2C19. This was confirmed in incubations with inhibitory antibodies. Whereas an anti-CYP2C9/2C19 antibody completely abolished desogestrel metabolism, anti-CYP3A4 and anti-CYP2E1 were not inhibitory. We conclude that CYP2C9 and possibly CYP2C19 and important isoforms catalysing the initial hydroxylation of desogestrel. SN - 0022-3565 UR - https://www.unboundmedicine.com/medline/citation/9864282/The_role_of_CYP2C_in_the_in_vitro_bioactivation_of_the_contraceptive_steroid_desogestrel_ L2 - http://jpet.aspetjournals.org/cgi/pmidlookup?view=long&pmid=9864282 DB - PRIME DP - Unbound Medicine ER -