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Chemical compound
Formestane
Trade names Lentaron, others Other names 4-Hydroxyandrost-4-ene-3,17-dione
AHFS /
Drugs.com
International Drug Names
Routes of administration
Intramuscular injection
Drug class
Aromatase inhibitor ;
Antiestrogen
ATC code
(8R ,9S ,10R ,13S ,14S )-4-hydroxy-10,13-dimethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H -cyclopenta[a ]phenanthrene-3,17-dione
CAS Number
PubChem
CID
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (
EPA )
ECHA InfoCard
100.153.838
Formula C 19 H 26 O 3
Molar mass 302.414 g·mol−1 3D model (
JSmol )
O=C4C(/O)=C3/CC[C@@H]2[C@H](CC[C@@]1(C(=O)CC[C@H]12)C)[C@@]3(C)CC4
InChI=1S/C19H26O3/c1-18-10-8-15(20)17(22)14(18)4-3-11-12-5-6-16(21)19(12,2)9-7-13(11)18/h11-13,22H,3-10H2,1-2H3/t11-,12-,13-,18+,19-/m0/s1
Y Key:OSVMTWJCGUFAOD-KZQROQTASA-N
Y
N Y
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(verify)
Formestane , formerly sold under the brand name Lentaron among others, is a
steroidal ,
selective
aromatase inhibitor which is used in the treatment of
estrogen receptor -positive
breast cancer in
postmenopausal women.
[1] The drug is not active orally, and was available only as an intramuscular depot injection. Formestane was not approved by the United States FDA and the injectable form that was used in Europe in the past has been withdrawn from the market.
[2] Formestane is an
analogue of
androstenedione .
Formestane is often used to suppress the production of estrogens from
anabolic steroids or
prohormones . It also acts as a prohormone to
4-hydroxytestosterone , an active steroid which displays weak
androgenic activity in addition to acting as a weak aromatase inhibitor.
Pharmacodynamics of aromatase inhibitors
Generation
Medication
Dosage
% inhibitiona
Classb
IC50 c
First
Testolactone
250 mg 4x/day
p.o.
?
Type I
?
100 mg 3x/week
i.m.
?
Rogletimide
200 mg 2x/day
p.o. 400 mg 2x/day
p.o. 800 mg 2x/day
p.o.
50.6% 63.5% 73.8%
Type II
?
Aminoglutethimide
250 mg mg 4x/day
p.o.
90.6%
Type II
4,500 nM
Second
Formestane
125 mg 1x/day
p.o. 125 mg 2x/day
p.o. 250 mg 1x/day
p.o.
72.3% 70.0% 57.3%
Type I
30 nM
250 mg 1x/2 weeks
i.m. 500 mg 1x/2 weeks
i.m. 500 mg 1x/1 week
i.m.
84.8% 91.9% 92.5%
Fadrozole
1 mg 1x/day
p.o. 2 mg 2x/day
p.o.
82.4% 92.6%
Type II
?
Third
Exemestane
25 mg 1x/day
p.o.
97.9%
Type I
15 nM
Anastrozole
1 mg 1x/day
p.o. 10 mg 1x/day
p.o.
96.7–97.3% 98.1%
Type II
10 nM
Letrozole
0.5 mg 1x/day
p.o. 2.5 mg 1x/day
p.o.
98.4% 98.9%–>99.1%
Type II
2.5 nM
Footnotes: a = In
postmenopausal women. b = Type I:
Steroidal ,
irreversible (
substrate-binding site ). Type II:
Nonsteroidal ,
reversible (binding to and interference with the
cytochrome P450
heme
moiety ). c = In
breast cancer
homogenates . Sources: See template.
References
^ Pérez Carrión R, Alberola Candel V, Calabresi F, et al. (1994). "Comparison of the selective aromatase inhibitor formestane with tamoxifen as first-line hormonal therapy in postmenopausal women with advanced breast cancer". Ann. Oncol . 5 (Suppl 7): S19–24.
PMID
7873457 .
^
"Formestane" .
Estrogens
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Steroidal:
Alfatradiol
Certain
androgens /
anabolic steroids (e.g.,
testosterone ,
testosterone esters ,
methyltestosterone ,
metandienone ,
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Certain
progestins (e.g.,
norethisterone ,
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Conjugated estriol
Conjugated estrogens
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Estradiol
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Estramustine phosphate
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estriol succinate ,
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Estrogenic substances
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Progonadotropins
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ER Tooltip Estrogen receptor antagonists (incl.
SERMs Tooltip selective estrogen receptor modulators /
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Aromatase inhibitors
Antigonadotropins
Androgens /
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Others
AR Tooltip Androgen receptor
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GPRC6A