Clinical application of 5 alpha-reductase inhibitors

The inhibitors of 5 alpha -reductase isoenzymes (1 and 2) can be schematica lly divided in three groups according they substrate specificity: a) pure o r preferential inhibitor of 5 alpha -reductase 1; b) pure or preferential i nhibitor of 5 alpha -reductase 2; c) dual inhibitors. Despite the fact that several steroidal and non-steroidal inhibitors have been synthesized and e xperimented in pharmacological models, only finasteride has been extensivel y used for clinical purposes. The largest application of finasteride in man has been human benign prostative hyperplasia (BPH). In addition, finasteri de has been recently used for treatment of male baldness with a 50% of obje ctive response. In women, finasteride has been used in some control trials for treatment of hirsutism with an objective favorable response. In conclus ion, finasteride appears be useful for BPH, baldness and hirsutism (with ca ution) treatment. On the basis of experimental observations on distribution of 1 and 2 isoenzymes in human skin, scalp and prostate, the dual inhibito rs should be more indicated for treatment of BPH and baldness. Similarly, t he dual inhibitors seem indicated in attempting to prevent prostatic cancer . The pure 5a-reductase 1 inhibitors seem the ideal drugs for treatment of acne and hirsutism.