Metabolism of Oral Contraceptives I. Metabolism of Ethynodiol Diacetate in Women

Abstract1. The metabolism of ethynodiol diacetate was investigated in four women. In seven days following oral administration, 58% dose was excreted in urine and 22% in faeces, predominantly in conjugated form. The urinary half-life was 15 h.2. Using a new and specific technique for isolation of ethynylated steroids involving pptn. of AgNO3 complexes, the less polar urinary metabolites identified were: norethindrone (3.6%, based on total urinary radioactivity), 17α-ethynyl-5β-estrane-3β,17β-diol (6.1%), 17α-ethynyl-5α-estrane-3α,17β-diol (1.1%), 17α-ethynyl-5β-estrane-3α, 17β-diol (0.4%), 17α-ethynyl-5α-estrane-3β,17β-diol (9.9%), and 17α-ethynyl-4,16-estradien-3-one (1.5%). No unchanged ethynodiol diacetate was found.3. Dehydration of the 17β-hydroxyl group to produce the last named metabolite appears to be a novel pathway.