Nebicapone (BIA 3-202), a reversible catechol-O-methyltransferase (COMT) inhibitor, is mainly metabolized by glucuronidation. Nebicapone is mainly peripherally acting inhibitor that decreases the biotransformation of L-DOPA to 3-O-methyl-DOPA by inhibition of COMT, and it is potential for the treatment of Parkinson's disease.