The field of menopause medicine is dominated by studies documenting the effectiveness of systemic estrogen or estrogen-progestin hormone therapy for the treatment of hot flashes caused by hypoestrogenism. The effectiveness of progestin-only systemic hormone therapy for the treatment of hot flashes is much less studied and seldom is utilized in clinical practice. A small number of studies have reported that progestins, including micronized progesterone, medroxyprogesterone acetate, and norethindrone acetate, are effective treatment for hot flashes. Progestin-only systemic hormone therapy might be especially helpful for postmenopausal women with moderate to severe hot flashes who have a contraindication to estrogen treatment.
Micronized progesterone
Micronized progesterone (Prometrium) 300 mg daily taken at bedtime has been reported to effectively treat hot flashes in postmenopausal women. In one study, 133 postmenopausal women with an average age of 55 years and approximately 3 years from their last menstrual period were randomly assigned to 12 weeks of treatment with placebo or micronized progesterone 300 mg daily taken at bedtime.1 Mean serum progesterone levels were 0.28 ng/mL (0.89 nM) and 27 ng/mL (86 nM) in the women taking placebo and micronized progesterone, respectively. Compared with placebo, micronized progesterone reduced daytime and nighttime hot flash frequency and severity. In addition, compared with placebo, micronized progesterone improved the quality of sleep.1
Most reviews conclude that micronized progesterone has minimal cardiovascular risk.2 Micronized progesterone therapy might be especially helpful for postmenopausal women with moderate to severe hot flashes who have a contraindication to estrogen treatment such as those at increased risk for cardiovascular disease or women with a thrombophilia. Many experts believe that systemic estrogen therapy is contraindicated in postmenopausal women with an American Heart Association risk score greater than 10% over 10 years.3 Additional contraindications to systemic estrogen include women with cardiac disease who have a thrombophilia, such as the Factor V Leiden mutation.4
For women who are at high risk for estrogen-induced cardiovascular events, micronized progesterone may be a better option than systemic estrogen for treating hot flashes. Alternatively, in these women at risk of cardiovascular disease a selective serotonin reuptake inhibitor, such as escitalopram, 10 mg to 20 mg daily, may be a good option for treating postmenopausal hot flashes.5
Medroxyprogesterone acetate
Medroxyprogesterone acetate, at a dosage of 20 mg daily, is an effective treatment for hot flashes. In a randomized clinical trial 27 postmenopausal women with hot flashes were randomly assigned to treatment with placebo or medroxyprogesterone acetate 20 mg daily for 4 weeks. Vasomotor flushes were decreased by 26% and 74% in the placebo and medroxyprogesterone groups, respectively.6
Depot medroxyprogesterone acetate injections at dosages from 150 mg to 400 mg also have been reported to effectively treat hot flashes.7,8 In a trial comparing the effectiveness of estrogen monotherapy (conjugated equine estrogen 0.6 mg daily) with progestin monotherapy (medroxyprogesterone acetate 10 mg daily), both treatments were equally effective in reducing hot flashes.9
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