Progesterone metabolism in hepatic microsomes. Effect of the cytochrome P-450 inhibitor, ketoconazole, and the NADPH 5 alpha-reductase inhibitor, 4-MA, upon the metabolic profile in human, monkey, dog, and rat.

Progesterone was incubated in the presence of NADPH with hepatic microsomes isolated from male and female human, monkey, dog, and rat and the effect of 17 beta-NN-diethylcarbamoyl-4-methyl-4-aza-5 alpha- androstan-3-one (4-MA), an NADPH 5 alpha-reductase inhibitor, and ketoconazole, a cytochrome P-450 inhibitor, upon oxidative metabolism was evaluated. 4-MA caused an increase in detectable oxidative products only with microsomes isolated from rat. An increase in 2 alpha- and 16 alpha-hydroxylation was observed in male rat, and an increase in the formation rate of nine products was observed in female rat. delta 6-Progesterone, 6 beta-, 15 alpha-, 16 alpha-, and 21-hydroxyprogesterone (6 beta-, 15 alpha-, 16 alpha-, and 21-OHP) were common products in both sexes of all species studied. Differences were observed in the formation rate of 2 alpha-, 2 beta-, 6 alpha-, 7 alpha-, and 17 alpha-OHPs. At the 2-carbon, microsomes isolated from both sexes of primates hydroxylated progesterone exclusively at the 2 beta-position. Microsomes from both dog sexes and female rat formed 2 alpha- and 2 beta-OHP, while microsomes isolated from male rat formed exclusively 2 alpha-OHP. 7 alpha-Hydroxylation was detected exclusively in rat, and 6 alpha-hydroxylation was detected in both dog and rat. 17 alpha-Hydroxylase activity in primates was detected only in microsomes from male human. IC50 values associated with ketoconazole inhibition of progesterone metabolism differed among species.(ABSTRACT TRUNCATED AT 250 WORDS)