Tibolone

Tibolone

Systematic (IUPAC) name
17-Hydroxy-7α-methyl-19-nor-17α-pregn-5(10)-en-20-yn-3-one
Clinical data
AHFS/Drugs.com	International Drug Names
Pregnancy category	ADEC Category D
Legal status	CA: Schedule IV
Routes of administration	oral
Identifiers
CAS Number	5630-53-5 N
ATC code	G03CX01 (WHO)
PubChem	CID: 444008
ChemSpider	392038 Y
UNII	FF9X0205V2 Y
KEGG	D01639 Y
ChEBI	CHEBI:32223 Y
ChEMBL	CHEMBL1558898 N
Synonyms	7α-Methylnoretynodrel; Org OD 14 (7α,17β)-17-ethynyl-17-hydroxy-7-methylestr-5(10)-en-3-one
Chemical data
Formula	C21H28O2
Molecular mass	312.446 g/mol
SMILES O=C4CCC\1=C(\C[C@H]([C@@H]2[C@@H]/1CC[C@]3([C@H]2CC[C@]3(C#C)O)C)C)C4
InChI InChI=1S/C21H28O2/c1-4-21(23)10-8-18-19-13(2)11-14-12-15(22)5-6-16(14)17(19)7-9-20(18,21)3/h1,13,17-19,23H,5-12H2,2-3H3/t13-,17-,18+,19-,20+,21+/m1/s1 Y Key:WZDGZWOAQTVYBX-XOINTXKNSA-N Y
NY (what is this?)  (verify)

Tibolone (INN, USAN, BAN) (brand name Livial, Tibofem) is a synthetic steroid drug with estrogenic, progestogenic, and weak androgenic actions which was introduced in 1988 and is used widely in Europe, Asia, Australasia, and, with the exception of the United States (where it is not available), the rest of the world. It is used mainly for treatment of endometriosis, as well as hormone replacement therapy in post-menopausal women. Tibolone has similar or greater efficacy compared to older hormone replacement drugs, but shares a similar side effect profile. It has also been investigated as a possible treatment for female sexual dysfunction.

Tibolone is a 19-nortestosterone derivative and is related structurally to other 19-nortestosterone progestins.

Pharmacology

Tibolone possesses a complex pharmacology. Its two major active metabolites, 3α-hydroxytibolone and 3β-hydroxytibolone, act as potent, fully activating agonists of the estrogen receptor (ER), with a high preference for ERα. Tibolone and its metabolite Δ⁴-tibolone act as agonists of the progesterone and androgen receptors, while 3α-hydroxytibolone and 3β-hydroxytibolone, conversely, act as antagonists of these receptors. Lastly, tibolone, 3α-hydroxytibolone, and 3β-hydroxytibolone act as antagonists of the glucocorticoid and mineralocorticoid receptors, with preference for the mineralocorticoid receptor.

Tibolone has tissue-selective estrogenic effects, with desirable effects in bone, the brain, and the vagina, and lack of undesirable action in the endometrium and breasts. Its tissue selectivity is the result of metabolism, enzyme modulation (e.g., of estrogen sulfatase and estrogen sulfotransferase), and receptor modulation that vary in different target tissues, and differs mechanistically from that of selective estrogen receptor modulators (SERMs) such as tamoxifen, which produce their tissue-selectivity via means of modulation of the ER. As such, to distinguish it from SERMs, tibolone has been described as a "selective tissue estrogenic activity regulator" (STEAR), and also as a "selective estrogen enzyme modulator" (SEEM).

Adverse effects

A report in September 2009 from Health and Human Services' Agency for Healthcare Research and Quality suggests that tamoxifen, raloxifene, and tibolone used to treat breast cancer significantly reduce invasive breast cancer in midlife and older women, but also increase the risk of adverse side effects.

See also

• Noretynodrel
• Etynodiol diacetate