Comparison of HRTs finds progesterone causes less bleeding.(hormone replacement therapy)

2002 DEC 5 - (NewsRx.com & NewsRx.net) -- Excessive bleeding, a troublesome side effect that causes many women to stop taking hormone replacement therapies (HRT), is less likely with progesterone than with more commonly used synthetic versions.

Results from a national clinical trial published in the November 2002 issue of the Journal of Obstetrics and Gynecology, show that a combination of estrogen and micronized progesterone (MP) causes fewer days and less intense bleeding than the most commonly used combination. Previous studies have shown that unacceptable bleeding is the reason that most women discontinue HRT during the first year of therapy.

Estrogen plus MP is a different combination therapy than estrogen plus medroxyprogesterone acetate (MPA), the most widely used HRT. Continuous estrogen plus MPA was used in the Women's Health Initiative study, which recently found that this form of HRT increased the risk of breast cancer, heart attack and stroke.

While MPA is a strong synthetic compound that mimics the action of progesterone, MP is chemically and functionally identical to the progesterone that women naturally make before menopause. Progestogens like MP and MPA are used to prevent problems that can develop in the uterus when estrogen is used by itself. MP is just as effective as MPA for that purpose.

"During the first 6 months, when many women stop taking HRT because of bleeding problems, we found that estrogen plus MP caused significantly less bleeding than the other combinations using MPA," said the study's senior author, Robert D. Langer, MD, MPH, professor of family and preventive medicine, University of California, San Diego (UCSD) School of Medicine. "Over 3 years, the number of unexpected bleeding episodes was virtually identical for placebo and estrogen plus MP, and about half as great as for the next best treatment, cyclical estrogen plus MPA."

"We also believe that the form of HRT with the least bleeding - estrogen plus MP - may be the form less likely to cause the increased health risks associated with estrogen plus MPA," Langer noted.

He said that previous results from the same study, the Postmenopausal Estrogen/Progestin Interventions (PEPI) trial, found that estrogen plus MP differed little from estrogen alone in effects on key heart disease risk factors, while MPA tempered some of those benefits. He added that studies in nonhuman primates have shown that MPA blocks both short-term and long-term ...