Effects of 5 alpha-reductase inhibitors on intraprostatic androgens in the rat

FCE 27837 is a novel inhibitor of 5 alpha-reductase, the enzyme responsible for the conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). The compound caused inhibition of human and rat prostatic enzymes, with IC50 values of 51 and 60 nM, respectively. The in vivo effect of FCE 27837 on 5 alpha-reductase was evaluated in adult male rats, treated orally at 10 mg/kg/day for 10 days. The compound caused 33 and 42% reductions in ventral prostate and seminal vesicle weights, respectively. The prostatic content of DHT, measured 6 h after the 10th dose of FCE 27837, was reduced by 75%, whereas T content increased by 442%. Similar effects were observed with 10 mg/kg/day of finasteride, whereas epristeride, tested at the same oral dose, was found to be the least effective compound, decreasing prostate weight by 22% and DHT content by 46%. Castration caused > 90% reductions in prostatic weight and prostatic DHT.