Fareston - General Information

A first generation selective estrogen receptor modulator (SERM). Like tamoxifen, it is an estrogen agonist for bone tissue and cholesterol metabolism but is antagonistic on mammary and uterine tissue. [PubChem]


Pharmacology of Fareston

Fareston is an antineoplastic hormonal agent primarily used in the treatment of advanced breast cancer. Fareston is a nonsteroidal agent that has demonstrated potent antiestrogenic properties in animal test systems. The antiestrogenic effects may be related to its ability to compete with estrogen for binding sites in target tissues such as breast. Fareston inhibits the induction of rat mammary carcinoma induced by dimethylbenzanthracene (DMBA) and causes the regression of already established DMBA-induced tumors. In this rat model, Fareston appears to exert its antitumor effects by binding the estrogen receptors. In cytosols derived from human breast adenocarcinomas, Fareston competes with estradiol for estrogen receptor protein.


Fareston for patients

Patient Information:

Vaginal bleeding has been reported in patients using Toremifene. Patients should be informed about
this and instructed to contact their physician if such bleeding occurs.

Patients with bone metastases should be informed about the typical signs and symptoms of hypercalcemia
and instructed to contact their physician for further assessment if such signs or symptoms occur.


Fareston Interactions

Drugs that decrease renal calcium excretion, eg, thiazide diuretics, may increase the risk of hypercalcemia in patients receiving FARESTON. There is a known interaction between antiestrogenic compounds of the triphenylethylene derivative class and coumarin-type anticoagulants (eg, warfarin), leading to an increased prothrombin time. When concomitant use of anticoagulants with FARESTON is necessary, careful monitoring of the prothrombin time is recommended.

Cytochrome P450 3A4 enzyme inducers, such as phenobarbital, phenytoin, and carbamazepine increase the rate of toremifene metabolism, lowering the steady-state concentration in serum. Metabolism of toremifene may be inhibited by drugs known to inhibit the CYP3A4-6 enzymes. Examples of such drugs are ketoconazole and similar antimycotics as well as erythromycin and similar macrolides. This interaction has not been studied and its clinical relevance is uncertain.


Fareston Contraindications

FARESTON is contraindicated in patients with known hypersensitivity to the drug.


Additional information about Fareston

Fareston Indication: For the treatment of metastatic breast cancer in postmenopausal women with estrogen receptor-positive or receptor-unknown tumors
Mechanism Of Action: Fareston is a nonsteroidal triphenylethylene derivative. Fareston binds to estrogen receptors and may exert estrogenic, antiestrogenic, or both activities, depending upon the duration of treatment, animal species, gender, target organ, or endpoint selected. The antitumor effect of toremifene in breast cancer is believed to be mainly due to its antiestrogenic effects, ie, its ability to compete with estrogen for binding sites in the cancer, blocking the growth-stimulating effects of estrogen in the tumor.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Toremifene
Synonyms: Not Available
Drug Category: Antineoplastic Agents; Selective Estrogen Receptor Modulators
Drug Type: Small Molecule; Approved; Investigational

Other Brand Names containing Toremifene: Acapodene; Fareston; Farestone; Toremifene Base; Toremifeno [Spanish]; Toremifenum [Latin]; Z-Toremifene;
Absorption: Well absorbed
Toxicity (Overdose): Not Available
Protein Binding: Greater than 99.5%
Biotransformation: Hepatic. Mainly by CYP3A4.
Half Life: 5 days
Dosage Forms of Fareston: Tablet Oral
Chemical IUPAC Name: 2-[4-[(Z)-4-chloro-1,2-di(phenyl)but-1-enyl]phenoxy]-N,N-dimethylethanamine
Chemical Formula: C26H28ClNO
Toremifene on Wikipedia:
Organisms Affected: Humans and other mammals