The original use for finasteride was for the reduction or slowing of balding patterns in men that is typically associated with DHT.  Finasteride is a DHT blocker and can be taken orally.  DHT is the evil conversion of testosterone into a very androgenic natural steroid that often causes balding in men, but with finasteride, this can be limited if not somewhat reversed.  It has been shown to cause a negative effect on sex drive, this theory can be tested on lab rats to improve the concept.  All balding patterns can be seen on older rats and tested for reversal.