page_title: Pharmacology of cyproterone acetate
section_title: Metabolism
hierarchical_section_title: Pharmacology of cyproterone acetate / Pharmacokinetics / Metabolism
caption_attribution_description: English: Metabolic pathways of cyproterone acetate in humans. "CPA is almost completely metabolized via the cytochrome P450 isoenzyme CYP3A4, and its main metabolite is 15β-OHCPA." Source: &#32;(April 2018).&#32;"Current understanding on pharmacokinetics, clinical efficacy and safety of progestins for treating pain associated to endometriosis". Expert Opin Drug Metab Toxicol&#32;14&#32;(4): 399–415. DOI:10.1080/17425255.2018.1461840. PMID 29617576. "The major metabolic steps are hydroxylation and deacetylation, while the D4-double bond is preserved. The antiandrogenic activity of 15β-hydroxy-CPA is similar to that of CPA, but the progestogenic efficacy is only 10% of that of CPA [17]." Source: Kuhl H&#32;(2011).&#32;"Pharmacology of Progestogens"&#32;(PDF). J Reproduktionsmed Endokrinol&#32;8&#32;(1): 157–177. "[CPA is metabolised via various degradation pathways, including via hydroxylation and conjugation steps. The major metabolite in serum is 15β-hydroxy-CPA.]" Source: &#32;(2015).&#32;"Hirsutismus – Medikamentöse Therapie Gemeinsame Stellungnahme der Deutschen Gesellschaft für Gynäkologische Endokrinologie und Fortpflanzungsmedizin e.V. und des Berufsverbands der Frauenärzte e.V.". Journal für Reproduktionsmedizin und Endokrinologie&#32;12&#32;(3): 102-149. ISSN 1810-2107.
context_page_description: The pharmacology of cyproterone acetate, concerns the pharmacology of the steroidal antiandrogen and progestin medication cyproterone acetate.
  CPA blocks the effects of androgens like testosterone in the body, which it does by preventing them from interacting with their biological target, the androgen receptor, and by reducing their production by the gonads and hence their concentrations in the body. In addition, it has progesterone-like effects by activating the progesterone receptor. By activating the PR, CPA has antigonadotropic effects and can inhibit fertility and suppress sex hormone production in both men and women. CPA can also produce weak and partial cortisol-like effects at very high doses under certain circumstances by activating the glucocorticoid receptor.
  CPA can be taken by mouth or by injection into muscle.
context_section_description: CPA is metabolized primarily by hydroxylation via CYP3A4, forming the major active metabolite 15β-hydroxycyproterone acetate. This metabolite circulates at concentrations approximately twice those of CPA, and has similar antiandrogen activity to that of CPA but only 10% of its activity as a progestogen. As a result, the co-administration of CPA with drugs which inhibit CYP3A4 may increase its potency as a progestogen.
  Some CPA is reportedly metabolized by hydrolysis into cyproterone and acetic acid. However, unlike many other steroid esters, CPA is not extensively hydrolyzed, and much of the pharmacological activity of the drug is attributable to CPA itself in its unchanged form. Cyproterone has approximately one-third the potency of CPA as an antiandrogen and is devoid of progestogenic activity.
  The elimination half-life of oral CPA is relatively long at approximately 1.6 to 2.2 days (38 to 53 hours), but possibly as long as 3.6 to 4.3 days (86 to 100 hours). The half-life of 15β-OH-CPA with oral administration of CPA is 2.6 days. The elimination half-life of CPA is prolonged in obese patients, which may be due to relatively greater storage of CPA in fat. The elimination half-life of CPA is also longer in older individuals; it is approximately twice as long in elderly men than in younger men (95 hours and 45 hours, respectively). When given via depot intramuscular injection, CPA has an elimination half-life of 3 to 4.3 days while 15β-OH-CPA has a half-life of 5.2 days. The duration of action of a single intramuscular injection of CPA is about 14 to 20 days. The serum total clearance of CPA is approximately 2.32 ± 0.38 mL/min/kg. Levels of CPA and 15β-OH-CPA with oral administration decrease biphasically over a period of 24 to 120 hours.
caption: Metabolism of CPA.[168][26][169]
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