Hydroxyestrone diacetate (brand names Colpoginon, Colpormon, Hormobion, Hormocervix) (former developmental code name RD-310), or 16ñ-hydroxyestrone diacetate, also known as 3,16ñ-dihydroxyestra-1,3,5(10)-trien-17-one 3,16ñ-diacetate, is a synthetic, steroidal estrogen which has been marketed in France, Spain, Brazil, and Argentina. It is a derivative of 16ñ-hydroxyestrone with an acetate esters attached at the C3 and C16ñ positions.