Biological Activities of a New Steroidal Inhibitor of δ4-5α-Reductase

Abstract17β-N,N-Diethylcarbamoyl-4-methyl-4-aza-5α-androstan-3-one (4-MA), a known 5α-reductase inhibitor, was tested in a variety of bioassays designed to document its endocrinological spectrum. It proved to be a relatively nontoxic compound which showed little or no antifertility activity in either male or female rats, no significant estrogenic, progestational, androgenic, or gonadotropin-inhibiting potency, and it did not affect serum prolactin levels. 4-MA did, however, cause feminization of male fetuses carried by treated pregnant female rats. It also caused a cessation in growth of the ventral prostate and seminal vesicles of young adult male rats. Both the feminization of male fetuses and the inhibition of male sex accessory growth are believed to be a result of the inhibition of 5α-reductase by 4-MA.