Drug Information



Brand Name:Fareston Trade Name:toremifene
FDA Approved For:FARESTON is indicated for the treatment of metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors. Pediatric Use:There is no indication for use of FARESTON in pediatric patients.
Carcinogen:Conventional carcinogenesis studies in rats at doses of 0.12 to 12 mg/kg/day (about 1/100 to 1.5 times the daily maximum recommended human dose on a mg/m 2 basis) for up to 2 years did not show evidence of carcinogenicity. Studies in mice at doses of 1.0 to 30.0 mg/kg/day (about 1/15 to 2 times the daily maximum recommended human dose on a mg/m 2 basis) for up to 2 years revealed increased incidence of ovarian and testicular tumors, and increased incidence of osteoma and osteosarcoma. The significance of the mouse findings is uncertain because of the different role of estrogens in mice and the estrogenic effect of toremifene in mice. An increased incidence of ovarian and testicular tumors in mice has also been observed with other human antiestrogenic agents that have primarily estrogenic activity in mice.Mutagen:Toremifene has not been shown to be mutagenic in in vitro tests (Ames and E. Coli bacterial tests). Toremifene is clastogenic in vitro (chromosomal aberrations and micronuclei formation in human lymphoblastoid MCL-5 cells) and in vivo (chromosomal aberrations in rat hepatocytes). No significant adduct formation could be detected using 32 P post-labeling in liver DNA from rats administered toremifene when compared to tamoxifen at similar doses. A study in cultured human lymphocytes indicated that adducting activity of toremifene, detected by 32 P post-labeling, was about 1/6 that of tamoxifen at approximately equipotent concentrations. In addition, the DNA adducting activity of toremifene in salmon sperm, using 32 P post-labeling, was 1/6 and 1/4 that observed with tamoxifen at equivalent concentrations following activation by rat and human microsomal systems, respectively. However, toremifene exposure is fourfold the exposure of tamoxifen based on human AUC in serum at recommended clinical doses.
Manufacturer and/or Distributor:Orion Corp.

Adverse Reactions:

Adverse drug reactions are principally due to the antiestrogenic hormonal actions of FARESTON and typically occur at the beginning of treatment. The incidences of the following eight clinical toxicities were prospectively assessed in the North American Study. The incidence reflects the toxicities that were considered by the investigator to be drug related or possible drug related. (See Table) Approximately 1% of patients receiving FARESTON (n = 592) in the three controlled studies discontinued treatment as a result of adverse events (nausea and vomiting, fatigue, thrombophlebitis, depression, lethargy, anorexia, ischemic attack, arthritis, pulmonary embolism, and myocardial infarction). Serious adverse events occurring in patients receiving FARESTON in the three major trials are listed in the table below. (See Table) Other adverse events of unclear causal relationship to FARESTON included leukopenia and thrombocytopenia, skin discoloration or dermatitis, constipation, dyspnea, paresis, tremor, vertigo, pruritis, anorexia, reversible corneal opacity (corneal verticulata), asthenia, alopecia, depression, jaundice, and rigors. In the 200 and 240 mg FARESTON dose arms, the incidence of SGOT elevation and nausea was higher. Approximately 4% of patients were withdrawn for toxicity from the high-dose FARESTON treatment arms. Reasons for withdrawal included hypercalcemia, abnormal liver function tests, and one case of toxic hepatitis, depression, dizziness, incoordination, ataxia, blurry vision, diffuse dermatitis, and a constellation of symptoms consisting of nausea, sweating, and tremor. )

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