Antiestrogen

An antiestrogen is a drug which decreases estrogen signaling in the body. They do this either by acting as antagonists of the estrogen receptor or by inhibiting or suppressing estrogen production. Examples include selective estrogen receptor modulators like tamoxifen and raloxifene, which are partial agonists of the estrogen receptor and have mixed estrogenic and antiestrogenic effects in different tissues (but are predominantly antiestrogenic), estrogen receptor antagonists like fulvestrant, which are pure or silent antagonists with no capacity to activate the estrogen receptor, aromatase inhibitors like anastrozole and exemestane, which inhibit aromatase and thereby prevent the production of estrogens, and antigonadotropins like GnRH analogues, high-dose progestogens, and high-dose androgens, which suppress the function of the gonads and thereby prevent them from producing estrogens as well as other sex hormones.