Raloxifene
Benzothiophene SERM; no endometrial agonist activity
Mechanism of Action
Raloxifene is a second-generation benzothiophene-class SERM that functions as an estrogen receptor antagonist in breast and uterine tissue while acting as an agonist in bone. Unlike triphenylethylene SERMs (tamoxifen, clomiphene), raloxifene does not exhibit partial agonist activity in endometrial tissue, significantly reducing endometrial proliferation risk. It maintains bone mineral density via ER agonism in osteoblasts/osteoclasts and improves lipid profiles. Raloxifene is studied for osteoporosis prevention, breast cancer risk reduction, and as an alternative to tamoxifen for gynecomastia prevention with improved endometrial safety.
Evidence Level
Clinical Trial - Human
4 studies published
Studied For
Pharmacology
Molecular Weight
473.6 g/mol (HCl salt)
Half-Life
Approximately 27.7 hours (oral)
Bioavailability
Approximately 2% oral bioavailability (extensive first-pass glucuronidation)