About Raloxifene Selective estrogen-receptro modulator (SERM), Benzothiophene derivative, Osteoporosis in postmenopausal women. Mechanism of Action of Raloxifene Raloxifene is a selective estrogen-receptor modulator (SERM) that has been approved for use in the prevention and treatment of osteoporosis in postmenopausal women. A SERM interacts with estrogen receptors, functioning as an agonist in some tissues and an antagonist in other tissues. Raloxifene has estrogen agonist-like effects on bone and on cholesterol metabolism and antagonist-like effects on the endometrium and breasts- it produces some of the beneficial effects of estrogen without the possible adverse effects.