BOXED WARNING and additional important safety information:
FARESTON has been shown to prolong the QTc interval in a dose- and concentration-related manner. Prolongation of the QT interval can result in a type of ventricular tachycardia called Torsade de pointes, which may result in syncope, seizure, and/or death. Toremifene should not be prescribed to patients with congenital/acquired QT prolongation, uncorrected hypokalemia or uncorrected hypomagnesemia. Drugs known to prolong the QT interval and strong CYP3A4 inhibitors should be avoided.
FARESTON is contraindicated in patients with known hypersensitivity to the drug. Patients with a history of thromboembolic diseases should generally not be treated with FARESTON. As with other antiestrogens, tumor flare, hypercalcemia, and endometrial hyperplasia have been reported in some breast cancer patients being treated with FARESTON. In general, patients with preexisting endometrial hyperplasia should not be given long-term FARESTON treatment. During clinical trials involving 1157 patients treated with FARESTON or tamoxifen, the incidence of serious side effects were as follows: cardiac events (2.03% vs. 2.42%), ocular events (10.30% vs. 9.38%), thromboembolic events (3.21% vs. 3.28%), and elevated liver tests (26.2% and 23.7%), respectively.
References: FARESTON Prescribing Information, 2004. Data on file, GTx, Inc.. Hayes DF, Van Zyl JA, Hacking A, et al. Randomized comparison of tamoxifen and two separate doses of toremifene in postmenopausal patients with metastatic breast cancer. J Clin Oncol. 1995;13:2556-2566. Gershanovich M, Garin A, Baltina D, et al. A phase III comparison of two toremifene doses to tamoxifen in postmenopausal women with advanced breast cancer. Breast Cancer Res Treat. 1997;45:251-262. Pyrhönen S, Valavaara R, Modig H, et al. Comparison of toremifene and tamoxifen in postmenopausal patients with advanced breast cancer: a randomized double-blind, the ‘nordic’ phase III study. Br J Cancer. 1997;76:270-277.