A pharmacological review of selective oestrogen receptor modulators

Selective oestrogen receptor modulators (SERMs) are structurally diverse non-steroidal compounds that bind to oestrogen receptors and produce oestrogen agonist effects in some tissues and oestrogen antagonist effects in others. SERMs are being evaluated for a number of oestrogen-related diseases, including post-menopausal osteoporosis, hormone-dependent cancers, and cardiovascular disease. Several compounds that exhibit a SERM profile are currently available for clinical use, including clomiphene, tamoxifen, and toremifene (which are triphenylethylenes) and raloxifene (a benzothiophene). Clomiphene is used for the induction of ovulation in sub-fertile women attempting pregnancy. Tamoxifen and toremifene are both used to treat breast cancer. Tamoxifen may have beneficial effects on bone mineral density and serum lipids. The effects of toremifene on serum lipids are similar to that of tamoxifen. Both compounds have stimulatory effects on the endometrium. Raloxifene, indicated for the treatment and prevention of post-menopausal osteoporosis, has beneficial effects on bone mineral density and serum lipids, but does not increase the risk of endometrial hyperplasia or endometrial cancer. Recently, raloxifene was shown to reduce the incidence of vertebral fractures in otherwise healthy women with osteoporosis; in the same study, a reduced incidence of breast cancer was also observed. Similar to oestrogens, SERMs increase the incidence of venous thromboembolism. Several newer compounds that exhibit a SERM profile are also in clinical development, including other triphenylethylenes (droloxifene, idoxifene) and benzothiophenes (LY353381.HCl), benzopyrans (EM-800), and naphthalenes (CP-336,156).