Possible Interaction: Estradiol and Progestins

“Tension, irritability, and depressed mood were all significantly augmented during the progestin phase of cycles with 3 mg estradiol (P < 0.001).”

“After stratification for compound type, risk … were apparently higher among women reporting estradiol– progestin combined treatment vs. estradiol or conjugated estrogens alone, with ORs for more than 10 years of intake being ….4 (95% CI 0.7–8.6) and 1.3 (95% CI 0.5–3.7), respectively.”

“Therefore it seems that in postmenopausal women estradiol is the most active intranuclear estrogenic form and that concurrent progestin use can diminish the nuclear estradiol content presumably through a mechanism involving estradiol dehydrogenase.”

“Further, dual treatment with estradiol and progestin increased the numbers of putative tumor stem/progenitor cells.”

“… 17β-estradiol (… progestin , with a half-maximal effective concentration measured at about 30 pM. This effect of R5020 was completely reversed by the addition of physiological …-(1-propynyl)-4,9-estradien-3-one], but not by the antiandrogen hydroxyflutamide (α,α,α-trifluoro-2-methyl-4′-nitro-m-lactotoluidide).”

“Treatment of the transfected T47D cells with a combination of estradiol and the progestin R5020 led to a superinduction of chloramphenicol acetyltransferase activity, showing a synergistic action of these two steroids.”

“The hypothesis that 17 beta-estradiol or tamoxifen (TAM) can potentiate clinical response of endometrial cancer treated with progestin was tested in an ovariectomized nude mouse system, using a sex steroid receptor-positive and a receptor-negative human endometrial carcinoma.”

“Conclusions: The postmenopausal use of estradiol in combination with various progestogen regimens may weaken the pelvic floor, resulting in uterine prolapse.”

“Co-administration with a progestin (as we did with nomegestrol acetate) can reduce risks associated with unopposed oestradiol on reproductive tissue.”

“In the case of the other five reductases, gestagens had remarkably stronger inhibitory effects at a concentration of 25 μM (progesterone: 66-88% inhibition; drospirenone: 26-87% inhibition) in comparison to estrogens ( estradiol : 17-51% inhibition; ethinylestradiol: 14-79% inhibition) and androgens (14-78% inhibition).”