What Are "Designer Estrogens"?

Designer estrogens, SERMS, are two terms currently being used to describe the actions of a medication that acts as an estrogen on one tissue and an anti-estrogen on others. The ideal estrogen medication would switch of or off the effects of estrogen at different sites in the woman's body.

Tamoxifen and Evista (raloxifene), have some of these properties. Tamoxifen is the first SERM used by mainly breast cancer patients and has been shown to block the return of breast cancer in the other breast by 40 percent. The risk associated with Tamoxifen is that it may increase risk of developing blood clots and uterine cancer. Tamoxifen in postmenopausal women acts as an estrogen on bones and increases bone density, increases bone mass 1-3% per year. Neither Tamoxifen or Evista are as effective as Estrogen Replacement Therapy for increasing bone mass, or relieving hot flashes.

Evista (raloxifene), is the latest medication used in osteoporosis prevention. Unlike Tamoxifen, Evista is almost exclusively anti-estrogen in the uterus, it does not increase cell build up in the uterus. Evista has been shown to prevent bone loss and its effect on whether it will help prevent heart disease is being studied. Below see chart on comparison of Premarin and Evista (Raloxifene).

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OBGYN.net © 1999 Judith A. Norris, Ob-Gyn, RNP, OBGYN.net Editorial Advisor