Lasofoxifene is a third-generation, non-steroidal selective estrogen receptor modulator (SERM). It selectively binds to human ERα with an IC50 value of 1.5 nM and inhibits bone loss in ovariectomized rats. In clinical studies of postmenopausal osteoporosis, 0.5 mg/day lasofoxifene was associated with reduced risks of nonvertebral and vertebral fractures, ER-positive breast cancer, coronary heart disease, and stroke but an increased risk of venous thromboembolic events. Lasofoxifene has also been shown to act as an inverse agonist at the CB2 cannabinoid receptor, indicating its potential to be repurposed as a therapeutic for indications wherein CB2 is a target.
