Evista (R'aloxifene Hydrochloride) is an estrogen agonist/antagonist, referred to as a selective estrogen receptor modulator (SERM) and belongs to the benzothiophe class of compounds. The biological actions of R'aloxifene are largely mediated through binding to estrogen receptors. This binding results in activation of estrogenic pathways in some tissues (Agonism) and and the blockade of estrogenic pathways in other tissues (Antagonism).

(1) R'aloxifene is used to prevent and treat osteoporosis (condition in which the bones become thin and weak and break easily) in women who have undergone menopause (change of life; end of menstrual periods). R'aloxifene is also used to decrease the risk of developing invasive breast cancer (breast cancer that has spread outside of the milk ducts or lobules into the surrounding breast tissue) in women who are at high risk of developing this type of cancer or who have osteoporosis. R'aloxifene cannot be used to treat invasive breast cancer or to prevent invasive breast cancer from coming back in women who have already had the condition.

(2) R'aloxifene also cannot be used to decrease the risk of developing non-invasive breast cancer. R'aloxifene is in a class of medications called selective estrogen receptor modulators (SERMs). R'aloxifene prevents and treats osteoporosis by mimicking the effects of estrogen (a female hormone produced by the body) to increase the density (thickness) of bone. R'aloxifene decreases the risk of developing invasive breast cancer by blocking the effects of estrogen on breast tissue. This may stop the development of tumors that need estrogen to grow.