Clinical pharmacokinetics of toremifene

Toremifene is a chlorinated triphenylethylene derivative of tamoxifen approved for use in the treatment of patients with metastatic breast cancer. Toremifene is well tolerated in patients, and common adverse effects of this drug include vasomotor symptoms such as hot flashes and vaginal discharge. This compound is administered to patients orally at a dose of 60 mg/day, although alternative methods of administration have been investigated. Oral bioavailability is estimated to be approximately 100%. At steady state, toremifene and its metabolites are highly protein bound (>95%). Toremifene is metabolised in the liver by cytochrome P450 enzymes, and it is eliminated primarily in the faeces following enterohepatic circulation. The half-life of toremifene is approximately 5 days, and steady state is reached by 6 weeks depending on the dose given. The pharmacokinetics of toremifene have been shown to be altered by certain liver conditions, but age and kidney function do not appear to be as significant.