In the past several years, a number of artificial estrogens have been developed to provide some of the benefits of estrogen replacement therapy while avoiding some of the risks for women who aren't good candidates for MHT. In other words, the artificial estrogens act like estrogens with some of the body's tissues, but they don't act like estrogens with others. These so-called “designer estrogens” are more correctly referred to as selective estrogen receptor modulators or SERMs Some health care providers prescribe SERMs to combat bone loss in postmenopausal patients who can't or choose not to use MHT but who are at risk of developing osteoporosis. Following are the most common SERMs in use today:
Tamoxifen (sold under the brand name Nolvadex) has been in use for some years to help reduce the potential for recurrence of estrogen-dependent breast cancer in women with a history of that disease. Ongoing study and scrutiny of Tamoxifen indicate that it isn't an “ideal answer” for postmenopausal women. Some studies have linked it to an increased risk of endometrial polyps, blood clots, and possibly precancerous endometrial hyperplasia.
Raloxifene was approved by the FDA in 1997 for use in the prevention of osteoporosis, and was marketed in 1998 under the brand name Evista. Though still under study, raloxifene has been found to maintain a certain amount of bone density in some patients, without increasing the risk of breast or uterine cancer. Because it doesn't appear to have any adverse effects on the endometrium, women who still have their uterus don't need to take progestin or progesterone when on raloxifene. However, some studies show that raloxifene is only about half as effective as estrogen at increasing bone density. Raloxifene's effect on cholesterol is still unknown; though it appears to reduce LDL cholesterol, it hasn't been shown to increase “good” HDL cholesterol the way estrogen does. The risk of blood clots with raloxifene seems to be similar to that of estrogen, and raloxifene has shown no beneficial effect in reducing hot flashes. It actually increases hot flashes in some patients.
SERMs show great promise for postmenopausal treatment without the risks of traditional hormones. They are typically used for treatment of bone loss, and more recently, for vaginal atrophy. New versions of this category of drug are being developed, and side effects are being studied to see whether they are a good substitute for hormones in women who have those symptoms.
Lasofoxifene, one of the newer SERMs, was shown, at a 2005 meeting of the North American Menopause Society (NAMS), to relieve the symptoms of vaginal atrophy, and is the first SERM to definitively improve this menopausal symptom.