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.

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).

 
Breast
Uterine lining
Bone
Raises HDL
Estrogen
Stimulates breast tissues
Increases uterine lining
Increase bone mass
Increase HDL Decreases LDL
Tamoxifen
Blocks effects of estrogen on breast tissues
Increases uterine lining
Increase bone mass
Decrease LDL
Raloxifene
Blocks effects of estrogen on breast tissues
No effect on uterine lining
Increases bone mass
Decrease LDL
Phytoestrogens
Blocks effects of estrogen on breast tissues
Uncertain
Increases bone mass
Uncertain



 
Standard dose Hormone replacement. Premarin
Evista (Raloxifene)
Benefits
 
 
5-15% HDL (healthy cholesterol)
Cardiovascular disease not studied.
Osteoporosis
Proven
5%-8% BMD spine/hip
Fracture risk benefit unknown.
hot flashes, night sweats, vaginal drying and painful intercourse, mood swings and skin wrinkles&tone
No effect (may increase hot flashes)
Alzheimer's Disease
Studies indicate positive affects on memory
Not studied
Risks
 
 
Breast Cancer
In some studies with 8-10 yrs of standard dose estrogen , relative risk of 1.25
No increase risk in studies up to 3 yrs.
Breast Tenderness
Rare, usually limited to first few months of therapy
None
Vaginal Bleeding
Cyclic regime declining menses Daily regime beyond 9-10 months of therapy there should be no bleeding
No menses

References:

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

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