A decades-old treatment derived from progesterone may be as effective as estrogen for quelling hot flashes, a Canadian-led trial suggests.

Medroxyprogesterone is a synthetic version of the hormone progesterone, and was first made about 40 years ago when progesterone itself was not available in an oral form.

There is another hormone replacement option for women who shouldn't take estrogen, said Dr. Jerilynn Prior of Vancouver General Hospital.
(CBC)

The research may be good news for women who fear hormone replacement therapy following a large study in the U.S. The study, released in 2002, indicated HRT with estrogen and progestin increased women's risk of breast cancer, heart disease and stroke, compared to those taking a placebo.

"As a doctor who takes care of women who have very bad hot flashes, the good news is that those with migraine headaches, those with blood clots, those with other reasons why they shouldn't take estrogen, now they have an equally effective choice," study author Dr. Jerilynn Prior, a professor of endocrinology at the University of British Columbia, told CBC Newsworld on Friday.

Prior is also founder of the Centre for Menstrual Cycle and Ovulation Research at Vancouver General Hospital.

In a one-year, double-blind, randomized trial, Prior and her international colleagues directly compared medroxyprogesterone to the standard estrogen treatment for controlling hot flashes and night sweats.

The 41 women participating in the study were in their late 30s to early 50s, and were menstruating before menopause induced by removal of ovaries and uterus — a group that typically experiences the worst hot flashes. 

Medroxyprogesterone did not cause blood clots, breast cancer or increase migraine headaches, making it safer than estrogen, Prior said.

Both therapies reduced hot flashes and sweats, the team said in the January issue of the journal Clinical Science.

The researchers are doing a similar trial comparing the drug to the natural form of progesterone, to see how the hormones lead to changes in weight, cholesterol levels and blood pressure.

About 20 per cent of women experience severe symptoms in menopause as estrogen levels change.

The Society of Obstetricians and Gynaecologists of Canada says women can go on HRT to relieve symptoms such as hot flashes, night sweats and mood changes, but the therapy should be prescribed at the lowest effective dose to manage moderate to severe symptoms "for the appropriate duration."