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Details

Stereochemistry ACHIRAL
Molecular Formula C26H29NO.C6H8O7
Molecular Weight 563.6381
Optical Activity NONE
Defined Stereocenters 0 / 0
E/Z Centers 1
Charge 0

SHOW SMILES / InChI
Structure of TAMOXIFEN CITRATE

SMILES

OC(=O)CC(O)(CC(O)=O)C(O)=O.CC\C(=C(/C1=CC=CC=C1)C2=CC=C(OCCN(C)C)C=C2)C3=CC=CC=C3

InChI

InChIKey=FQZYTYWMLGAPFJ-OQKDUQJOSA-N
InChI=1S/C26H29NO.C6H8O7/c1-4-25(21-11-7-5-8-12-21)26(22-13-9-6-10-14-22)23-15-17-24(18-16-23)28-20-19-27(2)3;7-3(8)1-6(13,5(11)12)2-4(9)10/h5-18H,4,19-20H2,1-3H3;13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)/b26-25-;

HIDE SMILES / InChI

Molecular Formula C26H29NO
Molecular Weight 371.5146
Charge 0
Count
MOL RATIO 1 MOL RATIO (average)
Stereochemistry ACHIRAL
Additional Stereochemistry No
Defined Stereocenters 0 / 0
E/Z Centers 1
Optical Activity NONE

Molecular Formula C6H8O7
Molecular Weight 192.1235
Charge 0
Count
MOL RATIO 1 MOL RATIO (average)
Stereochemistry ACHIRAL
Additional Stereochemistry No
Defined Stereocenters 0 / 0
E/Z Centers 0
Optical Activity NONE

Description

Tamoxifen (brand name Nolvadex), is selective estrogen receptor modulators (SERM) with tissue-specific activities for the treatment and prevention of estrogen receptor positive breast cancer. Tamoxifen itself is a prodrug, having relatively little affinity for its target protein, the estrogen receptor (ER). It is metabolized in the liver by the cytochrome P450 isoform CYP2D6 and CYP3A4 into active metabolites such as 4-hydroxytamoxifen (4-OHT) (afimoxifene) and N-desmethyl-4-hydroxytamoxifen (endoxifen) which have 30–100 times more affinity with the ER than tamoxifen itself. These active metabolites compete with estrogen in the body for binding to the ER. In breast tissue, 4-OHT acts as an ER antagonist so that transcription of estrogen-responsive genes is inhibited. Tamoxifen has 7% and 6% of the affinity of estradiol for the ERα and ERβ, respectively, whereas 4-OHT has 178% and 338% of the affinity of estradiol for the ERα and ERβ. The prolonged binding of tamoxifen to the nuclear chromatin of these results in reduced DNA polymerase activity, impaired thymidine utilization, blockade of estradiol uptake, and decreased estrogen response. It is likely that tamoxifen interacts with other coactivators or corepressors in the tissue and binds with different estrogen receptors, ER-alpha or ER-beta, producing both estrogenic and antiestrogenic effects. Tamoxifen is currently used for the treatment of both early and advanced estrogen receptor (ER)-positive (ER+) breast cancer in pre- and post-menopausal women. Additionally, it is the most common hormone treatment for male breast cancer. Patients with variant forms of the gene CYP2D6 (also called simply 2D6) may not receive full benefit from tamoxifen because of too slow metabolism of the tamoxifen prodrug into its active metabolites. Tamoxifen is used as a research tool to trigger tissue-specific gene expression in many conditional expression constructs in genetically modified animals including a version of the Cre-Lox recombination technique. Tamoxifen has been shown to be effective in the treatment of mania in patients with bipolar disorder by blocking protein kinase C (PKC), an enzyme that regulates neuron activity in the brain. Researchers believe PKC is over-active during the mania in bipolar patients.

CNS Activity

Originator

Approval Year

Targets

Primary TargetPharmacologyConditionPotency
39.0 nM [IC50]
1660.0 nM [IC50]
580.0 nM [IC50]

Conditions

ConditionModalityTargetsHighest PhaseProduct
Primary
NOLVADEX
Preventing
NOLVADEX
Primary
NOLVADEX

Cmax

ValueDoseCo-administeredAnalytePopulation
63.6 ng/mL
30 mg single, oral
TAMOXIFEN blood
Homo sapiens
187 ng/mL
20 mg 1 times / day steady-state, oral
TAMOXIFEN plasma
Homo sapiens

AUC

ValueDoseCo-administeredAnalytePopulation
3370.1 ng × h/mL
30 mg single, oral
TAMOXIFEN blood
Homo sapiens
4110 ng × h/mL
20 mg 1 times / day steady-state, oral
TAMOXIFEN plasma
Homo sapiens

T1/2

ValueDoseCo-administeredAnalytePopulation
209.8 h
30 mg single, oral
TAMOXIFEN blood
Homo sapiens

Doses

AEs

Drug as perpetrator​

Drug as victim

Tox targets

PubMed

Sample Use Guides

In Vivo Use Guide
For patients with breast cancer, the recommended daily dose is 20-40 mg. Dosages greater than 20 mg per day should be given in divided doses (morning and evening).
Route of Administration: Oral
In Vitro Use Guide
HELNalpha and HELNbeta two human cervix adenocarcinoma cell lines derived from HeLa cells stably transfected with the reporter gene ERE-betaGlob-Luc-SVNeo and the expression plasmids ERalpha or ERbeta respectively, were used to quantify the antiestrogenic and estrogenic effects of Tamoxifen. These cells were routinely cultivated in DMEM phenol red free, supplemented with 5% sFBS, 2 mM glutamine, 1% penicillin/streptomycin, 1 mg/mL Geneticin, and 0.5 mkg/mL puromycin to ensure appropriate antibiotic selection. For the assay, cells were trypsinized from the maintenance flask with phenol red free trypsin (0.05%)-EDTA (0.02%) (HyClone, Logan, UT) and seeded in an opaque 96-well plate (Nunc) at a density of 7.5 x 10^4 cells/well in a final volume of 100 mkL of assay medium (DMEM, phenol red free, supplemented with 3% sFBS, 2 mM glutamine, and penicillin/streptomycin). Five hours later, cells were adherent. Serial dilutions of Tamoxifen or DMSO as diluent control were then added in the presence of a fixed concentration of 17beta-estradiol (10^-10 M in HELNalpha and 10^-9 M in HELNbeta) to triplicate microcultures. Faslodex (Tocris, 10^-8 M) was used as a baseline indicator. Cells were incubated for 20 h at 37 °C in a 5% CO2 humidified incubator before being processed for luciferase determination. Medium was aspirated and 100 mkL of a 1:1 mixture of LucLite (Perkin-Elmer, Life Science, Boston, MA)/assay medium was added to each well. Plates were then sealed with a Topseal and left in the dark for 10 min before luminescence activity was determined by counting the plates for 6 s in a beta-TopCount (Packard Instrument Company, Meriden, CT).
Substance Class Chemical
Record UNII
7FRV7310N6
Record Status Validated (UNII)
Record Version