Finasteride was initially marketed to treat prostate conditions under the name Proscar in 5mg pills. It was known to inhibit the formation of DHT, a major contributor to both prostate cancer and male pattern hair loss. Subsequent research showed that a 1mg daily dose of the same drug was sufficient to control hair loss for 83% of men after two years of treatment. Since 1998 this version has been marketed under the brand name Propecia and it remains the only prescription drug approved by the FDA .