Toremifene Citrate
Triphenylethylene SERM; tamoxifen analog with reduced endometrial risk
Mechanism of Action
Toremifene is a chlorinated triphenylethylene SERM, structurally similar to tamoxifen (chlorine substituent at the ethyl side chain). Like tamoxifen, it acts as an ER antagonist in breast tissue and a partial agonist in bone and endometrium. The chlorine modification results in less DNA adduct formation and potentially reduced endometrial proliferation risk compared to tamoxifen. Toremifene is metabolized by CYP3A4 (not CYP2D6 like tamoxifen), avoiding the CYP2D6 polymorphism issue that affects tamoxifen efficacy. Studied for breast cancer and as an alternative to tamoxifen with more favorable metabolic profile.
Evidence Level
Clinical Trial - Human
4 studies published
Pharmacology
Molecular Weight
406.0 g/mol (free base); 598.1 g/mol (citrate)
Half-Life
Approximately 5 days (oral)
Bioavailability
Approximately 100% oral bioavailability (estimated)