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
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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was not approved by the United States FDA and the injectable form that was used in Europe in the past has been withdrawn from the market.[ 2] Formestane is an analogue of androstenedione .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.
Chemistry
Synthesis
The synthesis of formestane was reported:[ 3] Related patents:[ 4] [ 5]
500pxclass=skin-invert-image
Reaction of androstenedione with alkaline hydrogen peroxide gives the 4,5-epoxyandrosta-3,17-dione, PC13633174. Addition of acid completes the synthesis of formestane.
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" .
^ Angela M. H. Brodie, Harry J. Brodie, & David A. Marsh, U.S. patent 4,235,893 (1980 to Individual).
^ Jr Roy H Bible & Placek Chester, US2908682 (1959 to GD Searle LLC).
^ Franco Faustini, US4757061 (1988 to Pfizer Italia SRL).
Estrogens and antiestrogens
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Steroidal: Alfatradiol
Certain androgens/anabolic steroids (e.g., testosterone , testosterone esters, methyltestosterone , metandienone , nandrolone esters) (via estrogenic metabolites)
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Progonadotropins
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Exclusively antagonistic: Elacestrant
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Others
# WHO-EM
‡ Withdrawn from market
Clinical trials:
† Phase III
§ Never to phase III
See also
Estrogen receptor modulators
Androgens and antiandrogens
Progestogens and antiprogestogens
List of estrogens
Androgen receptor modulators
AR Tooltip Androgen receptor
Agonists SARMs Tooltip Selective androgen receptor modulator
Nonsteroidal: 198RL26
ACP-105
AC-262,536
Acetothiolutamide
Acetoxolutamide
Andarine (acetamidoxolutamide, androxolutamide, GTx-007, S-4)
BMS-564,929
DTIB
Enobosarm (ostarine, MK-2866, GTx-024, S-22)
FTBU-1
GLPG-0492
GSK2881078
GSK-4336A
GSK-8698
LG121071 (LGD-121071)
LGD-2226
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LGD-3303
LGD-4033
LY305
JNJ-26146900
JNJ-28330835
JNJ-37654032
OPK-88004 (LY-2452473, TT-701)
ORM-11984
PF-06260414
R-1
RU-59063
S-1
S-23
S-40503
S-101479
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S42
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Antagonists
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Drospirenone
DU-41165
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EM-4350
EM-5854
EM-5855
EM-6537
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RU-15328
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Topterone
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GPRC6A
See also
Receptor/signaling modulators
Androgens and antiandrogens
Estrogen receptor modulators
Progesterone receptor modulators
List of androgens and anabolic steroids