Hydroxyprogesterone acetate (OHPA) (INN) (brand name Prodox), or 17α-hydroxyprogesterone acetate, also known as 17α-acetoxyprogesterone or simply acetoxyprogesterone, is an orally active steroidal progestin related to hydroxyprogesterone caproate (OHPC) which was discovered in 1953 and was first marketed by Upjohn in the United States in 1957. It is a derivative of progesterone and the acetate ester of 17α-hydroxyprogesterone, as well as the parent compound of a number of progestins including chlormadinone acetate, cyproterone acetate, medroxyprogesterone acetate, and megestrol acetate.