Retro-steroids. I. Metabolism of the progestogen 6-chloro-9 , 10 -pregna-1,4,6-triene-3,20-dione in man

The metabolism of the retro-steroid 6-chloro-9β,10α:-pregna-1,4,6-triene-3,20-dione (I) has been investigated following oral administration of C-7 tritium labeled drug to a normal woman. Of the total radioactive dose, 47% and 30% were excreted in the urine and feces respectively within 7 days. About 20% of the urinary radioactivity was unconjugated while 70% was released following hydrolysis with β-glucuronidase. Qualitative analysis of a large urine pool from patients receiving I has resulted in the isolation and identification of three metabolites; 6-chloro-20α-hydroxy-9β, 10α-pregna-1,4,6-trien-3-one (II), 6-chloro-20α hydroxy-9β,10α-pregna-4,6-dien-3-one (III) and 20α-hydroxy-9β, 10α-pregna-1,4,6,8(14)-tetraen-3-one (IV). No intact I could be found in the urine indicating that the steroid undergoes complete metabolism $\text{in vivo}$.