Analysis of information sources in references of the Wikipedia article "Cyproterone" in English language version.
The progestational effect [of CPA] is linked to the presence of the acetyl group at position C17 of the steroid. Consequently, the free alcohol of CPA, cyproterone, which lacks the acetyl group, is devoid of progestational properties. However, it still exerts antiandrogenic activity, although less pronounced than CPA. Consequently, cyproterone was the first compound falling into the nowadays well-known class of pure antiandrogens.
The only chemical difference between cyproterone and cyproterone acetate consists of a free or esterified hydroxyl group at C17 but this difference accounts for profound differences in the mechanism of action and possibilities for use in the intact organism. Both steroids are highly active antiandrogens at any route of administration, the acetate has a greater antiandrogenic potency than the free alcohol. With the exception of a slight depressive effect on the adrenals, cyproterone does not have other side-activities unrelated to antiandrogenicity. It has, therefore, been termed "pure antiandrogen". Cyproterone acetate has one major additional activity: it is one of the strongest gestagens that have ever been synthesized [23, 70, 32, 77], [...]
Cyproterone acetate is 250 and 3330 times as potent a progestational agent as progesterone and cyproterone alcohol (10< respectively (Clauberg assay). [...] The pure anti-androgens, such as cyproteron, block the receptors of the negative feedback system. An uninhibited secretion of the releasing factors and an increased production of gonadotropins results, so that the inhibitory effect on the endorgans may finally be overcome by overpoduction of testosterone (Neumann, 1971). Cyproterone acetate, however, with its marked progestational effect, inhibits the release of LH and FSH at the same time and thus has a lasting anti-androgenic effect (Neumann, 1970). Thus, cyproteron leads to an increase in LH, whereas cyproteron acetate inhibits both LH and FSH.
[...] In this investigation a number of normal male volunteers were treated for three weeks with 100 mg free cyproterone per day. Sebum production was measured by the Straufi-Pochi method before treatment and on the 7th, 10th, 11th, 15th, 18th, [...]
Limited clinical experience also exists with benorterone, the first anti-androgen tried in man, and with free cyproterone. In the late sixties benorterone was reported to give promising results in 93 androgenized women but was soon withdrawn from clinical trial, mainly because of the development of gynaecomastia in the male. As a big advantage compared with CPA, it was found to be effective not only orally but also topically. Free cyproterone, on the other hand, proved to be without clinical value for reasons that cannot be discussed here. Thus we are left with CPA as the only anti-androgen that is already on the market in several countries.
The progestational effect [of CPA] is linked to the presence of the acetyl group at position C17 of the steroid. Consequently, the free alcohol of CPA, cyproterone, which lacks the acetyl group, is devoid of progestational properties. However, it still exerts antiandrogenic activity, although less pronounced than CPA. Consequently, cyproterone was the first compound falling into the nowadays well-known class of pure antiandrogens.
[...] Hammerstein 1977). This consideration is based on the fact that free cyproterone is a potent anti- androgen without antigonadotrophic activity and causes, therefore, an increase in gonadotrophins and in androgens (Graf et al. 1974). In [...]
Cyproterone (6-chloro-17-hydroxy-1,2α-methylenepregna-4,6-diene-3,20-dione) and cyproterone acetate (17-acetoxy-6-chloro-1,2α-methylene-pregna-4,6-diene-3,20-dione) are powerful anti-androgens, which exert multiple actions in many species. Cyproterone acetate has three times the anti-androgenic potency of cyproterone, and also has some progestational properties (for review, see Neumann et al., 1970). [...] Cyproterone seemed to decrease the activity of 17α-hydroxysteroid dehydrogenase and of 5α-steroid reductase in human prostate in vitro, as it does in testes and liver of rats (Breuer & Hoffmann, 1967; Hoffmann & Breuer, 1968; Denef et al., 1968). Cyproterone acetate did not seem to have any direct effect on the activity of these two enzymes.
Contrary to benorterone, free cyproterone, and flutamide, CPA is not a pure anti- androgen. In fact, it is one of the most potent progestogens known and, in comparison to that potency, it is a relatively weak antiandrogen and a still weaker anti- gonadotropin.
Cyproterone which has a very weak biological progestogen potency exhibited low affinity for the progestogen-receptor (Table I).
Cyproterone (6-chloro-17a-hydroxy-1a,2a-methylene-pregna-4,6-diene-3,20-dione) and cyproterone acetate have received considerable attention as antispermatogenic substances. Cyproterone, which has·only weak antigonadotropic properties, was found to be a poor antispermatogenic agent (42). In contrast, cyproterone acetate, which inhibits gonadotropin secretion, was found to be an antispermatogenic agent (142).
While CPA alone probably suppresses ovulation, cyproterone, which possesses no progestational activity, does not!8,72
Free cyproterone was first tried as a therapy for precocious puberty by Bierich (1970, 1971). The results, however, did not show any significant improvement.
Cyproterone (6-chloro-17-hydroxy-1,2α-methylenepregna-4,6-diene-3,20-dione) and cyproterone acetate (17-acetoxy-6-chloro-1,2α-methylene-pregna-4,6-diene-3,20-dione) are powerful anti-androgens, which exert multiple actions in many species. Cyproterone acetate has three times the anti-androgenic potency of cyproterone, and also has some progestational properties (for review, see Neumann et al., 1970). [...] Cyproterone seemed to decrease the activity of 17α-hydroxysteroid dehydrogenase and of 5α-steroid reductase in human prostate in vitro, as it does in testes and liver of rats (Breuer & Hoffmann, 1967; Hoffmann & Breuer, 1968; Denef et al., 1968). Cyproterone acetate did not seem to have any direct effect on the activity of these two enzymes.
Cyproterone which has a very weak biological progestogen potency exhibited low affinity for the progestogen-receptor (Table I).
Cyproterone (6-chloro-17a-hydroxy-1a,2a-methylene-pregna-4,6-diene-3,20-dione) and cyproterone acetate have received considerable attention as antispermatogenic substances. Cyproterone, which has·only weak antigonadotropic properties, was found to be a poor antispermatogenic agent (42). In contrast, cyproterone acetate, which inhibits gonadotropin secretion, was found to be an antispermatogenic agent (142).
While CPA alone probably suppresses ovulation, cyproterone, which possesses no progestational activity, does not!8,72
Free cyproterone was first tried as a therapy for precocious puberty by Bierich (1970, 1971). The results, however, did not show any significant improvement.
Cyproterone (6-chloro-17-hydroxy-1,2α-methylenepregna-4,6-diene-3,20-dione) and cyproterone acetate (17-acetoxy-6-chloro-1,2α-methylene-pregna-4,6-diene-3,20-dione) are powerful anti-androgens, which exert multiple actions in many species. Cyproterone acetate has three times the anti-androgenic potency of cyproterone, and also has some progestational properties (for review, see Neumann et al., 1970). [...] Cyproterone seemed to decrease the activity of 17α-hydroxysteroid dehydrogenase and of 5α-steroid reductase in human prostate in vitro, as it does in testes and liver of rats (Breuer & Hoffmann, 1967; Hoffmann & Breuer, 1968; Denef et al., 1968). Cyproterone acetate did not seem to have any direct effect on the activity of these two enzymes.
Cyproterone which has a very weak biological progestogen potency exhibited low affinity for the progestogen-receptor (Table I).
While CPA alone probably suppresses ovulation, cyproterone, which possesses no progestational activity, does not!8,72
[...] Hammerstein 1977). This consideration is based on the fact that free cyproterone is a potent anti- androgen without antigonadotrophic activity and causes, therefore, an increase in gonadotrophins and in androgens (Graf et al. 1974). In [...]
