Raloxifene is the first among a new class of drugs called selective estrogen receptor modulators. Recent research has discovered that both natural estrogen and synthetic estrogen-like compounds interact with estrogen receptors in different ways.
The shape of the receptor changes to accommodate the shape of the estrogen like a water bed changes to conform to the body. The shape assumed by the receptor determines what type of action the estrogen will have on breast, uterus, heart and bone.
The new estrogen receptor modulators attempt to produce the positive effects of estrogen on heart and bone while preventing the cancer causing effects on breast and uterus.
Eleven thousand women taking raloxifene are being studied in more than 20 countries. Two years into a five year trial, raloxifene prevented bone loss in the spine and hips compared with calcium supplemented placebo. The effects on preventing fractures are still being studied.
For two years, the effects of raloxifene on cholesterol were evaluated throughout the trials and specifically in a six month trial of 390 women. So far, it has lowered total cholesterol and serum fibrinogens, a risk factor for heart disease. It did not appear to cause breast or uterine cancer to date.
Some prominent experts have raised concerns that raloxifene may block the protective action of estrogen in the brain, thus speeding up the onset of Alzheimer's in women at risk for contracting the disease. Right now this connection is still unproven but obviously very worrisome.
A few years ago, raloxifene's cousin, tamoxifen, a drug used to prevent breast cancer recurrence, was suggested as a safe alternative to hormone replacement therapy. Tamoxifen appeared to prevent breast cancer while helping preserve bone and having a positive effect on the heart.
However, when the proper long term studies were performed a different picture emerged. First of all, tamoxifen's protective effect against breast cancer lasted about five years. After five years, the breast tissue appeared to become resistant to tamoxifen and tamoxifen may have actually caused more cancer.
Meanwhile, it was found that tamoxifen increases bone loss in women taking it before menopause and stabilizes bone mass in women after menopause. As for tamoxifen's initial beneficial effect in preventing heart attacks, it was disproved in later studies. Tamoxifen also increases the risk of cancer of the uterus.
Tamoxifen does have a few annoying side effects. These include hot flashes, nausea, vomiting in 25 percent, and, less frequently, depression, skin rashes, irregular bleeding, blood clotting, visual problems and liver enzymes changes.
Why would a healthy menopausal woman want to take tamoxifen? This question arose in 1992 when healthy women were being urged to participate in a large tamoxifen trail for breast cancer prevention launched by the US National Cancer Institute .
In England, five deaths from liver disease were linked to tamoxifen. These deaths prompted Britain's Medical Research Council to refuse to back the tamoxifen prevention trial.
At that time, Dr. Adriane Fugh-Berman, Director of the National Women's Health Network , posed the question: "Is this disease prevention or disease substitution?" This question may have to be posed for raloxifene and its relatives.
It's too early to say whether raloxifene will turn out to be the new wonder drug. In about thirty years we will accurately know whether this new drug truly offers a good and reasonable option to the menopausal woman. The outcome of long term clinical trials on whether the benefits of HRT outweigh the risks for healthy postmenopausal women are still pending.
Sandra Covey, author of The Menopause Industry (Hunter House, 1994), says that the industry has constructed the illusion of choice, between death and deterioration and medications with serious side effects. Much of what passes for patient information, she argues, is actually a carefully constructed marketing exercise. Complex issues are minimized. Incomplete and confusing studies are presented as dogma.
Meanwhile, Canadian women are not flocking to take hormones, only about 15 percent of them versus about 50 percent of American women who take them. Baby boomers are looking long and hard at the alternatives and defining their own choices.
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