Abstract: The present invention provides for the preparation of compounds,namely, 3-phenanthridinones and their derivatives and their unique ability to inhibit 5-alpha-reductase or their isozymes thereof in mammals enabling said compounds for treating hyperandrogenic conditions of acne, androgenic alopecia, male pattern baldness,female hirsutism,benign prostatic hyperplasia, prostatitis and prostatic cancer.

Abstract: A tetrahydropyridine derivative having substituents on three rings represented by the following formula (1): ##STR1## (wherein A represents sulfur atom, sulfoxide group or sulfone group; R.sub.1 represents an amino group substituted with a specific substituent or a specific aliphatic oxy group; R.sub.2 and R.sub.3 each represents hydrogen atom or a hydroxy group; and m and n are each an integer of from 0 to 4; provided that when m and n are 2 or above, R.sub.2 's and R.sub.3 's may be either the same or different from each other respectively, that when A is sulfur atom and R.sub.1 is cyclohexylamino group and R.sub.2 is hydrogen atom, R.sub.3 is hydroxy group, that when A is sulfoxide group and R.sub.1 is cyclohexylamino group or 4-hydroxycyclohexylamino group, R.sub.2 is hydrogen atom and R.sub.3 is hydrogen atom or hydroxy group and that when A is sulfone group and R.sub.1 is cyclohexylamino group, R.sub.2 and R.sub.