COMPARISON OF FINASTERIDE (PROSCAR(R)) AND SERENOA REPENS (PERMIXON(R)) IN THE INHIBITION OF 5-ALPHA REDUCTASE IN HEALTHY MALE-VOLUNTEERS

A total of 32 healthy male volunteers (age range 20-30 years) were enr olled in a 1-week open, randomized, placebo-controlled study comparing finasteride (Proscar(R)), a 5 alpha-reductase inhibitor, with Permixo n(R), the plant extract of Serenoa repens. The objective of the study was to evaluate the effect of single and multiple doses of the drugs o n the inhibition of 5 alpha-reductase as assessed by serum dihydrotest osterone level determination. Following baseline measurements on day 1 , the subjects were randomized to finasteride 5 mg once a day (n = 10) , Permixon 80 mg X 2 twice a day (n = 11), or to placebo once a day (n = 11) for 7 days. Serum testosterone and dihydrotestosterone levels, were determined on day 1 (baseline and 12 h) and on days 2 (24 h), 3 ( 48 h), 4 (72 h), 6 (120 h), and 8 (168 h). After 12 h, a single dose o f finasteride 5 mg reduced the serum dihydrotestosterone level by 65% (p less than or equal to 0.01). The decreases ranged from -52 to -60% with multiple doses of finasteride 5 mg once a day (p less than or equ al to 0.01). As in the placebo group, there was no effect of Permixon on the serum dihydrotestosterone level. No significant difference was detected between finasteride and Permixon or between finasteride and p lacebo with respect to serum testosterone, except on days 3 and 6, res pectively (p less than or equal to 0.05). However, the corresponding s erum testosterone levels remained within the normal ranges. These data confirm the efficacy of finasteride as inhibitor of 5 alpha-reductase . The lack of effect of Permixon on the dihydrotestosterone plasma lev els does not support the hypothesis of a prostatic mechanism of action through the inhibition of 5 alpha-reductase.