Clinical pharmacokinetics of toremifene

Toremifene is a chlorinated triphenylethylene derivative of tamoxifen appro ved for use in the treatment of patients with metastatic breast cancer. Tor emifene is well tolerated in patients, and common adverse effects of this d rug include vasomotor symptoms such as hot flashes and vaginal discharge. T his compound is administered to patients orally at a dose of 60 mg/day, alt hough 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%). Toremifen e is metabolised in the liver by cytochrome P450 enzymes, and it is elimina ted primarily in the faeces following enterohepatic circulation. The half-l ife 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 signi ficant.