Osaterone acetate

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Osaterone acetate
Osaterone acetate.svg
Clinical data
Trade namesYpozane
Other namesTZP-4238; Gestoxarone acetate; 2-Oxachloromadinone acetate; 17α-Acetoxy-6-chloro-2-oxa-6-dehydroprogesterone; 17α-Acetoxy-6-chloro-2-oxapregna-4,6-diene-3,20-dione
Routes of
By mouth (tablets)
Drug classSteroidal antiandrogen; Progestogen; Progestin; Progestogen ester
Pharmacokinetic data
Protein bindingOsaterone acetate: 90%
15β-Hydroxyosaterone acetate: 80%[1]
(Both mainly to albumin)[1]
Metabolites15β-Hydroxyosaterone acetate[1]
Elimination half-lifeDogs: 80 hours to 197 ± 109 hours[1][2]
ExcretionBile: 60%[1]
Urine: 25%[1]
  • [(1R,3aS,3bR,9aR,9bS,11aS)-1-acetyl-5-chloro-9a,11a-dimethyl-7-oxo-2,3,3a,3b,9,9b,10,11-octahydroindeno[4,5-h]isochromen-1-yl] acetate
CAS Number
PubChem CID
ECHA InfoCard100.215.750 Edit this at Wikidata
Chemical and physical data
Molar mass406.90 g·mol−1
3D model (JSmol)
  • CC(=O)C1(CCC2C1(CCC3C2C=C(C4=CC(=O)OCC34C)Cl)C)OC(=O)C
  • InChI=1S/C22H27ClO5/c1-12(24)22(28-13(2)25)8-6-16-14-9-18(23)17-10-19(26)27-11-20(17,3)15(14)5-7-21(16,22)4/h9-10,14-16H,5-8,11H2,1-4H3/t14-,15+,16+,20-,21+,22+/m1/s1

Osaterone acetate, sold under the brand name Ypozane, is a medication which is used in veterinary medicine in Europe in the treatment of enlarged prostate in dogs.[1][3][4] It is given by mouth.[1]

Osaterone acetate is an antiandrogen, and hence is an antagonist of the androgen receptor, the biological target of androgens like testosterone and dihydrotestosterone.[1] It is also a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone.[1]

Osaterone acetate was introduced for veterinary use in 2007.[5] It is marketed in Europe.[6][1]



Osaterone acetate is used in veterinary medicine in Europe in the treatment of benign prostatic hyperplasia (BPH) in dogs.[1][3][4] It has been found to produce remission of clinical symptoms of BPH in 83% of dogs for six months after a single one-week course of treatment,[7] and can be used long-term.[4]

Available forms

Osaterone acetate comes in the form of 1.875 mg, 3.75 mg, 7.5 mg, and 15 mg oral tablets for veterinary use.[1]

Side effects

Side effects of osaterone acetate include diminished sperm quality (for up to 6 weeks post-treatment), transient elevation of liver enzymes (caution should be observed with known liver disease), vomiting, diarrhea, polyuria/polydipsia, lethargy, and hyperplasia of the mammary glands.[8] It can also decrease cortisol levels, interfere with adrenocorticotropic hormone response, induce or exacerbate adrenal insufficiency, and exacerbate diabetes mellitus.[9][8]



Osaterone acetate is a steroidal antiandrogen, progestin, and antigonadotropin.[1] It has virtually no estrogenic or androgenic activity.[3] Its side-effect profile indicates that it possesses clinically relevant glucocorticoid activity.[9][8] An active metabolite of osaterone acetate, 15β-hydroxyosaterone acetate, has potent antiandrogenic activity similarly to osaterone acetate.[1] Osaterone acetate treats BPH in dogs by reducing the actions of androgens in the prostate gland.[1]


The major active metabolite of osaterone acetate is 15β-hydroxyosaterone acetate.[1] Osaterone acetate has a long biological half-life of 80 hours to 197 ± 109 hours in dogs.[1][2]


Osaterone acetate, also known as 2-oxachloromadinone acetate, as well as 17α-acetoxy-6-chloro-2-oxa-6-dehydroprogesterone or 17α-acetoxy-6-chloro-2-oxapregna-4,6-diene-3,20-dione, is a synthetic pregnane steroid and a derivative of progesterone and 17α-hydroxyprogesterone.[6] It is a derivative of the less potent chlormadinone acetate.[3] The medication is the C17α acetate ester of osaterone.[6]


Osaterone acetate was introduced for veterinary use in Europe under the brand name Ypozane in 2007.[6][5][1]

Society and culture

Generic names

Osaterone acetate is the generic name of the drug.[6] Osaterone is the INN of the deacetylated parent compound.[6]

Brand names

Osaterone acetate is marketed under the brand name Ypozane by Virbac.[6]


Osaterone acetate is available widely throughout Europe, including in Belgium, Finland, France, Germany, Italy, the Netherlands, Norway, Poland, Sweden, Switzerland, and the United Kingdom.[6]


Osaterone acetate was also investigated in Japan in the treatment of prostate cancer and BPH in humans but was ultimately never marketed for such purposes.[3][10]


  1. ^ a b c d e f g h i j k l m n o p q r s t "Ypozane for Dogs" (PDF). European Medicines Agency.
  2. ^ a b Maddison JE, Page SW, Church D (2008). Small Animal Clinical Pharmacology. Elsevier Health Sciences. pp. 536–. ISBN 978-0-7020-2858-8.
  3. ^ a b c d e Weber GF (22 July 2015). Molecular Therapies of Cancer. Springer. pp. 316–. ISBN 978-3-319-13278-5.
  4. ^ a b c Greer ML (18 December 2014). Canine Reproduction and Neonatology. Teton NewMedia. pp. 296–. ISBN 978-1-4987-2850-8.
  5. ^ a b Emmerich IU, Ungemach FR (2008). "Neue Arzneimittel für Kleintiere 2007". Tierärztliche Praxis Ausgabe K: Kleintiere/Heimtiere. 36 (5): 311–22. doi:10.1055/s-0038-1622691.
  6. ^ a b c d e f g h "Osaterone". Drugs.com.
  7. ^ Cote E (9 December 2014). Clinical Veterinary Advisor: Dogs and Cats. Elsevier Health Sciences. pp. 848–. ISBN 978-0-323-24074-1.
  8. ^ a b c Lamm C, Makloski C (28 May 2012). Theriogenology, An Issue of Veterinary Clinics: Small Animal Practice. Elsevier Health Sciences. pp. 112–. ISBN 978-1-4557-4447-3.
  9. ^ a b Ettinger SJ, Feldman EC (24 December 2009). Textbook of Veterinary Internal Medicine. Elsevier Health Sciences. pp. 2055–. ISBN 978-1-4377-0282-8.
  10. ^ Schröder FH, Radlmaier A (2009). "Steroidal Antiandrogens". In Jordan VC, Furr BJ (eds.). Hormone Therapy in Breast and Prostate Cancer. Humana Press. pp. 325–346. doi:10.1007/978-1-59259-152-7_15. ISBN 978-1-60761-471-5.

Further reading

External links