Raloxifene Shows Promise As Ideal Hormone Therapy For Some Women

SAN FRANCISCO, CA -- January 28, 1998 -- A novel hormone therapy drug, raloxifene, exhibits different effects on postmenopausal and premenopausal women, according to UCSF researchers.

In the first study of the new drug on healthy, menstruating women, the UCSF team evaluated its reproductive effects on premenopausal women. To date, human studies of raloxifene, in which UCSF has participated, have only been conducted on postmenopausal women.

Valerie Baker, M.D., lead author of the UCSF study and Robert Jaffe, M.D., senior author, report their findings in the current issue of the Journal of Clinical Endocrinology and Metabolism.

Raloxifene was developed by Eli Lilly and Company and was approved by the Food and Drug Administration for postmenopausal women in December 1997.

Previous UCSF studies of raloxifene on postmenopausal women led to its recent approval. The drug is an alternative to estrogen replacement therapy and is intended for women who, because of medical reasons or personal preference, choose not to take estrogen after menopause.

"In the current study, we wanted to determine how a woman's uterus, pituitary glands and ovaries respond to raloxifene before she starts menopause," said Jaffe, who is the director of the UCSF Reproductive Endocrinology Center and UCSF Fred Gellert professor of reproductive medicine and biology.

During the UCSF study, a total of 31 reproductive age women received raloxifene during different phases of their menstrual cycles. According to Baker and Jaffe, raloxifene neither affected ovulation nor altered the length of the menstrual cycle. However, the women's estrogen levels increased.

"It is important to know that the effects of raloxifene differ depending on a woman's present ovarian function," Baker said. "One should not generalize about the use of raloxifene between postmenopausal and premenopausal women."

In previous UCSF studies of raloxifene in postmenopausal women, researchers found that it is perhaps one of the safest and most effective hormone therapy drugs because of its unique characteristics, Baker said.

Raloxifene, which belongs to a class of drugs called selective estrogen receptor modulators (SERMs), both simulates and blocks the actions of estrogen depending on the organ system, Jaffe said.

"We found that unlike other SERMs, raloxifene has a positive, estrogen-like effect on a postmenopausal woman's bones and cholesterol levels, yet it does not mimic estrogen's adverse effects on her breasts and uterus," Jaffe said.

Estrogen acts by binding to structures called receptors in various target tissue cells, which then stimulate different responses, Jaffe said. For instance, estrogen can cause tissue growth in a woman's breasts and uterine lining, and over time, may increase her risk of breast or endometrial cancer.

At the same time however, estrogen has been proven to significantly reduce a woman's risk of osteoporosis, Jaffe explains. The hormone may also fight heart disease in a woman by lowering both her harmful cholesterol levels (LDL) and her total cholesterol.

Raloxifene is expected to be available in pill form for postmenopausal women this month.