Spotlight on Estradiol and Norgestimate as Hormone Replacement Therapy in Postmenopausal Women

Abstract

The focus of this review is hormone replacement therapy (HRT) with continuous administration of micronized, oral 17β-estradiol 1 mg/day (herein referred to as continuous estradiol) plus micronized, oral norgestimate 90 μg/day administered for 3 days then withdrawn for 3 days in a 6-day repeating sequence (herein referred to as intermittent norgestimate).

According to data from randomized, comparative trials of 1 year’s duration, continuous estradiol 1 mg/day plus intermittent norgestimate 90 μg/day relieves climacteric symptoms (vasomotor symptoms and vulvovaginal atrophy) in postmenopausal women. Continuous estradiol 1 mg/day plus intermittent norgestimate 90 μg/day appeared as effective as estradiol 1 mg/day alone or continuous estradiol 2 mg/day plus continuous norethisterone acetate 1 mg/day in the treatment of postmenopausal women with vasomotor symptoms. Continuous estradiol 1 mg/day plus intermittent norgestimate 90 μg/day was as effective as continuous estradiol 1 mg/day in causing the maturation of vaginal epithelial cells.

In a randomized, double-blind study, bone mineral density (BMD) increased to a significantly greater extent and the rate of bone turnover was slower in postmenopausal women treated with continuous oral estradiol 1 mg/day plus intermittent norgestimate 90 μg/day than in placebo-treated patients.

Two randomized, double-blind studies indicated that the addition of norgestimate 90 μg/day to continuous estradiol 1 mg/day did not attenuate the beneficial effects of estradiol on lipid parameters. Continuous estradiol 1 mg/day plus intermittent norgestimate 90 μg/day was associated with increases in mean serum high density lipoprotein (HDL)-cholesterol levels and decreases in total cholesterol, low density lipoprotein (LDL)-cholesterol and lipoprotein (a) levels, compared with baseline. There was no statistically significant increase in triglyceride levels.

In comparative trials, continuous oral estradiol 1 mg/day plus intermittent oral norgestimate 90 μg/day was well tolerated. Headache, breast pain or discomfort, abdominal pain or discomfort, uterine bleeding, dysmenorrhea, edema, nausea and depression were the most commonly reported adverse events. Continuous estradiol 1 mg/day plus intermittent oral norgestimate 90 μg/day was associated with a favorable uterine bleeding profile that improved over time. In a randomized trial, 80% of women were free from bleeding (irrespective of spotting) during month 12 of treatment. Norgestimate 90 μg/day was effective in protecting postmenopausal women against induction of endometrial hyperplasia by continuous estradiol 1 mg/day.

In conclusion, data from a limited number of randomized studies indicate that HRT with continuous estradiol 1 mg/day plus intermittent norgestimate 90 μg/day is effective in relieving climacteric symptoms, increasing BMD and slowing the rate of bone turnover in postmenopausal women. This HRT regimen is well tolerated and is associated with a similar incidence of adverse events to that reported in recipients of continuous estradiol 1 mg/day. The norgestimate component of the regimen provides good endometrial protection and is associated with a favorable bleeding profile. Long-term studies investigating the associated risk of breast cancer and thromboembolic events in recipients of continuous estradiol plus intermittent norgestimate are needed. In the meantime, continuous oral estradiol plus intermittent oral norgestimate can be regarded as an effective new option for HRT in postmenopausal women.