Efficacy of Every-Other-Day Administration of Conjugated Equine Estrogen and Medroxyprogesterone Acetate on Gonadotropin-Releasing Hormone Agonists Treatment in Women with Endometriosis

We performed a randomized controlled study to determine the efficacy of add-backed therapy by every-other-day administration of 0.625 mg conjugated equine estrogen (CEE) and 2.5 mg medroxyprogesterone acetate (MPA) on GnRH agonists (GnRH-a) treatment in Japanese women with symptomatic endometriosis. At the end of treatment, serum estrone and estradiol levels in the add-back group (n = 11) were significantly higher than those in the control group (n = 10). The assessment of Beecham classification by bimanual examination, serum CA-125 levels, and the frequency of genital bleeding revealed no significant differences between the two groups. The add-back group showed reduced Kupperman indices relative to those of the control group, and could prevent the loss of bone density. These findings led to a conclusion that GnRH-a therapy added back by every-other-day administration of 0.625 mg CEE and 2.5 mg MPA was a safe and effective treatment for Japanese women with endometriosis.