Toremifene (Mechanism of Action)

In this article, we will discuss Toremifene (Mechanism of Action). So, let’s get started.

Mechanism of Action

Toremifene is a nonsteroidal triphenylethylene derivative. Toremifene 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. In general, however, nonsteroidal triphenylethylene derivatives are predominantly antiestrogenic in rats and humans and estrogenic in mice. In rats, toremifene causes regression of established dimethylbenzanthracene (DMBA)-induced mammary tumors. The antitumor effect of toremifene in breast cancer is believed to be mainly due to its antiestrogenic effects, i.e., its ability to compete with estrogen for binding sites in the cancer, blocking the growth-stimulating effects of estrogen in the tumor.

Pharmacodynamics

Toremifene causes a decrease in the estradiol-induced vaginal cornification index in some postmenopausal women, indicative of its antiestrogenic activity. Toremifene also has estrogenic activity as shown by decreases in serum gonadotropin concentrations (FSH and LH).

Effects on Cardiac Electrophysiology

The effect of 20 mg, 80 mg, and 300 mg of toremifene on QT interval was evaluated in a double-blind, randomized study in healthy male subjects aged 18 to 45 years. The QT interval was measured at steady state of toremifene (Day 5 of dosing), including the time of peak plasma concentration (Tmax), at 13 time points (4 ECGs/time point) over 24
hours post dose in a time matched analysis. The 300 mg dose of toremifene (approximately five times the highest
recommended dose 60 mg) was chosen because this dose produces exposure to toremifene that will cover the expected exposures that may result from potential drug interactions and hepatic impairment.

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