TY - JOUR T1 - The preparations JF - Drug and Therapeutics Bulletin JO - Drug Ther Bull SP - 76 LP - 76 DO - 10.1136/dtb.4.19.76 VL - 4 IS - 19 A2 - , Y1 - 1966/09/16 UR - http://dtb.bmj.com/content/4/19/76.1.abstract N2 - The various progestagens used differ in potency, but their potency ratios in humans are not precisely known because different assay methods give different results. Nevertheless for clinical purposes the rank order of milligram potency seems to be approximately as follows: norethisterone and ethynodiol (most potent), norethynodrel, lynoestrenol, megestrol acetate (least potent). ER -