Progesterone effective for hot flushes, night sweats up to 10 years after final menstruation

The Endocrine Society 92nd Annual Meeting

SAN DIEGO — Healthy, normal-weight women within 10 years of their final menstrual flow may benefit from oral micronized progesterone to reduce hot flushes and night sweats.

Results of an intent-to-treat analysis showed that women assigned to progesterone experienced a 56% decrease in vasomotor symptoms during 12 weeks of treatment compared with a 28% decrease among women assigned to placebo.

Oral micronized progesterone may be an effective therapy for treatment-seeking healthy women who do not want or should not take estrogen, which is currently the only effective therapy for decreasing vasomotor symptoms, according to Jerilynn C. Prior, MD, professor of endocrinology and metabolism at University of British Columbia, Vancouver.

The randomized, masked, placebo-controlled trial included 133 healthy, non-obese (mean BMI, 24.7) women with moderate to severe vasomotor symptoms. The women were middle-aged (mean, 55 years), primarily white (91%) and a mean 4.3 years had elapsed since last menstrual flow.

Prior and Christine Hitchcock, PhD, also from the University of British Columbia, randomly assigned women to progesterone in a 300-mg dose (n=75) or identical placebo (n=58) before sleep each night for 12 weeks. Using data from self-recorded questionnaires, physical measurements and fasting blood tests, the researchers determined the effectiveness of progesterone on vasomotor symptoms.

“Progesterone was highly efficient, much more so than placebo,” Prior said during the clinical trial symposium.

The primary outcome was vasomotor score, defined as the average sum of women’s self-recorded intensity of vasomotor symptoms times number each day during the last 28 days of therapy. The baseline vasomotor score was 17, and women experienced a mean 6.8 symptoms per day.

Progesterone was also associated with a significantly lower number of overall hot flushes and night sweats compared with placebo. The researchers observed a 48% decrease among women assigned to progesterone vs. a 22% decrease with placebo.

The researchers reported no serious adverse events associated with progesterone.

“This is the first evidence that oral micronized progesterone, which is molecularly identical to the natural hormone, is effective for women with symptomatic hot flashes,” Prior said in a press release.

The progesterone used in this study (Prometrium) is manufactured from a steroid in yams, and is currently available only by prescription in the United States and Canada.

According to Prior, the researchers have secured funding for a randomized controlled trial of oral micronized progesterone on perimenopausal vasomotor symptoms, an area for which there is currently no evidence-based therapy. – by Matthew Brannon and Katie Kalvaitis

For practicing endocrinologists, it is very helpful to have information regarding the effectiveness of this medication in reducing hot flashes. There are obviously women who have contraindications to estrogen and in whom using this typical pro-gestational agent, medroxyprogesterone acetate, is fraught with side effects and metabolic abnormalities. It is not clear to me how the researchers chose the dose of 300 mg, as opposed to other medications that are available in the 100- or 200-mg doses. I also do not yet have a complete understanding of when one might consider progesterone to be contraindicated. But, having another option for our patients is important and I think that the study was done well.

– Carol H. Wysham, MD

Assistant Clinical Professor of Medicine at the University of Washington School of Medicine,
Section Head of the Department of Endocrinology at Rockwood Clinic in Spokane, Wash.

For more information:

Prior JC. S192. Presented at: The Endocrine Society 92nd Annual Meeting and Expo; June 19-22, 2010; San Diego.