Control of testosterone 5alpha-reductase activity in the human hyperplastic prostate

This 1978 study investigated the inhibition of testosterone 5alpha-reductase, an enzyme responsible for converting testosterone to the active hormone DHT in the prostate, as a potential treatment for benign prostatic hyperplasia (BPH). Various compounds, including heparin and metabolites of spironolactone, were tested for their ability to inhibit this enzyme. Heparin showed competitive inhibition but had no significant effect in rats, while spironolactone metabolites were ineffective. Progesterone and hydroxylated progestins also inhibited the enzyme, with effectiveness depending on hydroxyl group positioning. However, progesterone required higher concentrations than expected to inhibit DHT conversion, likely due to extensive metabolism in prostatic tissue. The study highlighted the potential of testosterone 5alpha-reductase inhibitors in managing BPH.