Estradiol enantate
Estradiol enantate, sold under the brand names Perlutal and Topasel among others, is an estrogen medication which is used in hormonal birth control. It is formulated in combination with dihydroxyprogesterone acetophenide (DHPA; algestone acetophenide), a progestin, and is used as a combined injectable contraceptive. Estradiol enantate is not available alone. The medication is given by injection into muscle once a month.
Side effects of estradiol enantate include breast tenderness, breast enlargement, nausea, headache, and fluid retention. The drug is a synthetic estrogen and hence is an agonist of the estrogen receptor (ER), the biological target of estrogens like estradiol. Estradiol enantate is an estrogen ester and a long-lasting prodrug of estradiol in the body. Because of this, it is considered to be a natural and bioidentical form of estrogen.
Estradiol enantate was first described by 1954, and was first studied in combination with DHPA as a combined injectable contraceptive in 1964. The combination was introduced for clinical use by the mid-1970s. Estradiol enantate is not available as a standalone medication (i.e., by itself without DHPA). The combination is available in Latin America and Hong Kong, and was also previously marketed in Spain and Portugal.
Estriol (medication)
Estriol is a far less potent estrogen than is estradiol, and is a relatively weak and atypical estrogen. Given by subcutaneous injection in mice, estradiol is about 10-fold more potent than estrone and about 100-fold more potent than estriol. In most tissues, such as the liver and endometrium, estriol is weakly estrogenic, but in the vaginal epithelium, it produces pronounced and full estrogenic responses. The medication has been found to reduce hot flashes, improve vaginal atrophy, reverse the postmenopausal decline in skin thickness and collagen content, suppress gonadotropin secretion, and produce proliferation of breast epithelium. Conversely, estriol does not consistently affect bone resorption or fracture risk, does not increase breast density or the risk of breast cancer, and, at oral dosages of 2 to 4 mg/day, does not affect liver proteins, lipid metabolism, or hemostatic parameters. Additionally, vaginal estriol does not appear to produce endometrial proliferation or increase the risk of endometrial hyperplasia, and some studies have found this to be the case for oral estriol as well. On the other hand, it appears that estriol may be able to stimulate the growth of active breast cancer. Via the oral route, estriol has approximately 30% of the potency of estradiol on hot flashes relief and suppression of follicle-stimulating hormone secretion and about 20% of the potency of estradiol on stimulation of liver production of high-density lipoprotein (HDL) cholesterol. In relation to its differing effects, estriol can be considered a safer estrogen than estradiol.