Estradiol benzoate/progesterone

Estradiol benzoate/progesterone (EB/P4), sold under the brand names Duogynon and Sistocyclin among others, is a combination medication of estradiol benzoate (EB), an estrogen, and progesterone (P4), a progestogen. It has been formulated both as short-acting oil solutions and long-acting microcrystalline aqueous suspensions and is given by injection into muscle either once or continuously at regular intervals. EB/P4 was one of the first combined estrogen and progestogen medications to be introduced for medical use. It was first marketed in Germany as an oil solution in 1950. Microcrystalline EB/P4 in aqueous suspension was developed and marketed under the brand name Sistocyclin several years later. EB/P4 was eventually superseded by longer-acting parenteral estrogen–progestogen combinations as well as by oral estrogen–progestogen combinations. EB/P4 has been used to treat menstrual disorders such as secondary amenorrhea and menstrual irregularity, as a form of emergency contraception within 48 hours of sexual intercourse, and as a test for pregnancy. In the form of a microcrystalline aqueous suspension, EB/P4 has particularly been used to treat functional uterine bleeding. EB/P4 has been studied in the treatment of breast cancer in women and found to be effective. EB/P4 is or has been available for use by intramuscular injection both in the form of short-acting oil solutions (e.g., Duogynon, Lutrogen) and long-acting microcrystalline aqueous suspensions (e.g., Clinomin Forte, Sistocyclin). These are provided as ampoules, with the oil-solution ampoules containing 2–3 mg EB and 12.5–50 mg progesterone and the aqueous-suspension ampoules containing 10 mg EB and 200 mg progesterone. The crystal sizes in microcrystalline EB/P4 in aqueous suspension (Sistocyclin) are 0.01 to 0.02 mm for EB crystals and 0.02 to 0.1 mm for P4 crystals. An oil-solution ampoule containing 30 mg EB and 30 mg P4 (brand name Vermagest) is used as an injectable emergency contraceptive. Clinomin Forte is an aqueous suspension of EB/P4 that additionally contains lidocaine and remains available today.