Cyproterone

Cyproterone

Clinical data
Routes of administration	Oral, topical
ATC code	None
Identifiers
IUPAC name (1S,2S,3S,5R,11R,12S,15R,16S)-15-Acetyl-9-chloro-15-hydroxy-2,16-dimethylpentacyclo[9.7.0.0²,⁸.0³,⁵.0¹²,¹⁶]octadeca-7,9-dien-6-one
Synonyms	SH-80881; SH-881; NSC-758636; 6-Chloro-17α-hydroxy-1α,2α-methylenepregna-4,6-diene-3,20-dione
CAS Number	2098-66-0 Y
PubChem (CID)	5284537
ChemSpider	4447594 Y
UNII	E61Q31EK2F Y
ChEMBL	CHEMBL142130 Y
ECHA InfoCard	100.218.313
Chemical and physical data
Formula	C22H27ClO3
Molar mass	374.90098 g/mol
3D model (Jmol)	Interactive image
SMILES CC(=O)[C@]1(CC[C@@H]2[C@@]1(CC[C@H]3[C@H]2C=C(C4=CC(=O)[C@@H]5C[C@@H]5[C@]34C)Cl)C)O
InChI InChI=1S/C22H27ClO3/c1-11(24)22(26)7-5-14-12-9-18(23)17-10-19(25)13-8-16(13)21(17,3)15(12)4-6-20(14,22)2/h9-10,12-16,26H,4-8H2,1-3H3/t12-,13+,14-,15-,16-,20-,21-,22-/m0/s1 Y Key:DUSHUSLJJMDGTE-ZJPMUUANSA-N Y
NY (what is this?)

Cyproterone (INN) (developmental code names SH-80881, SH-881), also known as 1,2α-methylene-6-chloro-δ⁶-17α-hydroxyprogesterone is a steroidal, pure antiandrogen that was studied in the mid to late 1960s and early 1970s but was never marketed for medical use. It is the free alcohol or non-17α-acetylated analogue of cyproterone acetate (CPA), an antiandrogen, progestin, and antigonadotropin that was introduced instead and is widely used clinically. Along with benorterone, BOMT, and flutamide, cyproterone was one of the first pure antiandrogens to be developed.

It is important to clarify that the term cyproterone is often used as a synonym for cyproterone acetate, and when the term occurs, what is usually being referred to is, confusingly, CPA and not actually cyproterone.

Like CPA, cyproterone is a potent antiandrogen. However, it has approximately three-fold lower potency as an antagonist of the androgen receptor (AR) relative to CPA. Similarly to CPA, cyproterone is actually a weak partial agonist of the AR, and hence has the potential for both antiandrogenic and androgenic activity in some contexts. Unlike CPA (which is an extremely potent progestogen), cyproterone is a pure antiandrogen and is virtually devoid of progestogenic activity. As such, it is not an antigonadotropin, and is actually progonadotropic in males, increasing gonadotropin and testosterone levels due to inhibition of AR-mediated negative feedback on the hypothalamic-pituitary-gonadal axis.