Selective estrogen receptor modulators (SERMs) exhibit a pharmacologic profile characterized by estrogen agonist activity in some tissues with estrogen antagonist activity in other tissues. The first widely used SERM, tamoxifen, has estrogen antagonist activity in breast tissue but shows estrogen-like activity in other tissues. Raloxifene is another SERM in clinical use, and it was developed to avoid some of the undesirable estrogen agonist actions of other SERMs to improve the drug safety

profile. Raloxifene has been introduced for clinical use in treatment and prevention of postmenopausal osteoporosis.