Afimoxifene is a selective estrogen receptor modulator

Selective estrogen receptor modulator

Selective Estrogen Receptor Modulators are a class of compounds that act on the estrogen receptor. A characteristic that distinguishes these substances from pure receptor agonists and antagonists is that their action is different in various tissues, thereby granting the possibility to selectively...

 which is the active metabolite

Metabolite

Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...

 of tamoxifen

Tamoxifen

Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, hence tamoxifen may be characterized as a mixed agonist/antagonist...

. Afimoxifene is a transdermal gel formulation

Pharmaceutical formulation

Pharmaceutical formulation, in pharmaceutics, is the process in which different chemical substances, including the active drug, are combined to produce a final medicinal product.-Stages and timeline:...

 and is being developed by Ascend Therapeutics, Inc. under the trademark TamoGel.

Afimoxifene has completed a phase II clinical trial for the treatment of cyclical mastalgia

Mastalgia

Mastodynia, mastalgia or mammalgia are names for a medical symptom that means breast pain .Pain can range from minor discomfort to severely incapacitating pain...

.

A study in France on 55 women showed that rubbing afimoxifene on the skin was as good as tamoxifen tablets at slowing breast cancer growth. A US trial will compare 6 weeks use before breast cancer surgery. Skin application can reduce systemic levels by a factor of nine and this is expected to reduce the unpleasant side-effects of tamoxifen.