Proscar is a specific inhibitor of 5a-reductase, which is the enzyme responsible for converting testosterone into DHT (dihydrotestosterone). Proscar efficiently reduce the serum concentration of DHT, therefore minimizing the unwanted androgenic effects that result from its presence. The effect of Proscar is quite rapid. Due to the very specific nature of finasteride, Proscar has little effect on the other hormones in the body. Proscar shows great potential for the steroid using athlete. In many instances, Proscar can allow the athlete the use of steroid compounds such as Testosterone enanthate, Sustanon etc... -- more about PROSCAR --