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)
The bioavailability of estriol is markedly increased with vaginal administration compared to oral administration. The relative bioavailability of oral estriol was found to be about 10% of that of vaginal estriol. In accordance, a single dose of 8 mg oral estriol and of 0.5 mg vaginal estriol have been found to produce similar circulating concentrations of estriol. It has been said that 0.5 to 1 mg vaginal estriol may be equivalent in clinical effect to 8 to 12 mg oral estriol. The high bioavailability of vaginal estriol is due to rapid absorption and low metabolism in atrophic vaginal mucosa. Vaginal estriol at typical clinical dosages results both in high local concentrations of estriol in the vagina and in systemic action. Vaginal administration of low doses of 30 µg estriol and of higher doses of 0.5 and 1 mg estriol have been found to produce equivalent local effects in the vagina and improvement of vaginal symptoms, suggesting that a saturation of estrogenic effect of vaginal estriol has been reached in the vagina by a dose of only 30 µg estriol. In contrast to higher doses of vaginal estriol however, 30 µg/day estriol is not associated with systemic effects. Similarly, the use of 0.5 mg vaginal estriol twice a week instead of daily has been said to largely attenutate the systemic effects of estriol. Whereas oral estriol results in high levels of estriol conjugates which greatly exceed those of unconjugated estriol, vaginal estriol has been found to produce levels of unconjugated estriol and estriol conjugates that are similar.