Pharmacodynamics EB is an estrogen, or an agonist of the estrogen receptors, the biological target of estrogens like endogenous estradiol. It is an estradiol ester and prodrug of estradiol with a longer duration of action than estradiol when administered by intramuscular injection in oil solution or aqueous suspension. P4 is a progestogen, or an agonist of the progesterone receptors, the biological target of progestogens like endogenous progesterone. The full endometrial transformation dosage of EB/P4 in oil solution is 1 to 2 mg EB and 20 to 25 mg P4 by intramuscular injection daily for 10 to 14 days, whereas the full endometrial transformation dosage of EB/P4 in microcrystalline aqueous suspension is a single intramuscular injection of 10 mg EB and 200 mg P4. For comparison, the full endometrial transformation dosage of estradiol valerate and hydroxyprogesterone caproate in oil solution (brand name Gravibinon) is a single intramuscular injection of 10 mg estradiol valerate and 250 to 375 mg hydroxyprogesterone caproate. Endometrial transformation normally occurs during the luteal phase of the menstrual cycle; it is induced by endogenous progesterone following adequate priming by endogenous estradiol. The decidua (pregnancy-type endometrium) induction dosage of EB/P4 in oil solution is 2 to 5 mg EB and 20 to 100 mg P4 by intramuscular injection daily for 5 to 7 weeks, whereas the decidua induction dosage of EB/P4 in microcrystalline aqueous suspension is 10 to 20 mg EB and 200 to 250 mg P4 in microcrystalline aqueous suspension by intramuscular injection once per week for about 6 weeks. For comparison, the decidua induction dosage of estradiol valerate and hydroxyprogesterone caproate in oil solution is about the same as that of microcrystalline EB/P4 in aqueous suspension. The decidua induction dosages of estrogen and progestogen combinations are pseudopregnancy dosages. Pharmacokinetics EB/P4 is administered by intramuscular injection a single time or continuously at regular intervals, depending on the indication. Amorphous EB/P4 in oil solution (e.g., Duogynon, Lutrogen) is reported to have a duration of action of 2 days in terms of the progestogen component, and hence is a short-acting preparation, whereas microcrystalline EB/P4 in aqueous suspension (e.g., Sistocyclin) has a duration of 10 to 12 days, and hence is a long-acting preparation. A study found that a single intramuscular injection of 10 mg microcrystalline EB in aqueous suspension with a 0.05 mm crystal size (similar to that in Sistocyclin) resulted in a maximal 7-fold increase in estradiol excretion on the 2nd day after injection and maintained elevated estradiol excretion for 17 days.
Estradiol benzoate/progesterone
Estradiol pivalate/progesterone
Estradiol enantate/algestone acetophenide
Estradiol/dydrogesterone
Estradiol benzoate/testosterone propionate
Estradiol/estradiol enanthate
Estradiol benzoate/estradiol phenylpropionate
Mestranol/hydroxyprogesterone acetate