Nitecapone (INN; OR-462) is a drug which acts as a selective inhibitor of the enzyme catechol O-methyl transferase (COMT). It was patented as an antiparkinson medication but was never marketed. Nitecapone (INN; OR-462) is a drug which acts as a selective inhibitor of the enzyme catechol O-methyl transferase (COMT). It was patented as an antiparkinson medication but was never marketed.