Estradiol cypionate/hydroxyprogesterone caproate (EC/OHPC), sold under the brand name Sinbios, is a combination medication of estradiol cypionate (EC), an estrogen, and hydroxyprogesterone caproate (OHPC), a progestin, which was reportedly used as a combined injectable contraceptive in women in the early 1970s. It contained 5 mg EC and 250 mg OHPC in oil solution, was provided in the form of 1 mL ampoules, and was administered by intramuscular injection at regular intervals. The medication was manufactured by the pharmaceutical company Mavi in Mexico.
- Rudel HW, Kinel FA (September 1972). "Oral Contraceptives. Human Fertility Studies and Side Effects". In Tausk M (ed.). Pharmacology of the Endocrine System and Related Drugs: Progesterone, Progestational Drugs and Antifertility Agents. Vol. II. Pergamon Press. pp. 385–469. ISBN 978-0080168128. OCLC 278011135.