Propecia Description. Propecia is a drug that is used to treat male baldness. It is produced by Merck, and the main ingredient in this drug is Finasteride. Merck also holds the patent for Propecia since 1997.Unlike others, this was the only medicine on baldness that was in the form of an oral pill.Other trade names of the drug are Proscar.t is produced by Merck, and the main ingredient in this drug is Finasteride. Merck also holds the patent for Propecia since 1997. Unlike others, this was the only medicine on baldness that was in the form of an oral pill. Other trade names of the drug are Proscar.