What is the mechanism of action (MOA) of Ospemifene?

Ospemifene functions primarily as an estrogen agonist specifically in the vaginal tissues, which is pivotal for its role in addressing specific symptoms of vulvar and vaginal atrophy due to menopause. By acting as an estrogen agonist in the vaginal epithelium, ospemifene helps to stimulate the vaginal lining, promoting thickening and improving moisture and elasticity. This action alleviates discomfort associated with vaginal atrophy, such as dryness and dyspareunia (pain during intercourse), thus enhancing the quality of life for postmenopausal women.

The ability of ospemifene to selectively target estrogen receptors in the vaginal tissues, while having different effects elsewhere in the body, is critical to its mechanism. This selective action avoids some of the risks associated with systemic estrogen therapy, making it a safer alternative for managing menopausal symptoms localized to the vagina.