An antiestrogen is a compound that blocks the action of estrogen. Most synthetic antiestrogens have agonistic or antagonistic activity depending on the tissue and the endogenous estrogen mileu. The triphenylethylene derivatives, clomiphene and tamoxifen, are the antiestrogens in greatest clinical use. Their biologic effects, clinical indications, and risks are reviewed. Novel antiestrogens which are beginning to be studied clinically include the benzothiophene derivative, raloxifene and the "pure" antiestrogens such as ICI 182,780. New clinical indications for existing compounds as well as the development of novel antiestrogens may lead to better treatment options for endocrine-dependent conditions.
Reproductive Endocrinology Center, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California.
Reprint requests to: Robert B. Jaffe, MD, Reproductive Endocrinology Center, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA 94143-0132.
Authors whose names are accompanied by an asterisk (*) have indicated, in accordance with the Accreditation Council for Continuing Medical Education (ACCME) Standards, that they have a relationship which could be perceived by some people as a real or apparent conflict of interest, but do not feel it has influenced their participation.