Ved at hæmme decarboxylase med en DDC- hæmmer bliver COMT hovedmetaboliseringsvejen for levodopa perifert og katalyserer omdannelsen af levodopa til 3- O- methyldopa (3- OMD), en potentiel skadelig metabolit af levodopa.
With inhibition of the decarboxylase by a DDC inhibitor, COMT becomes the major peripheral metabolic pathway catalyzing the conversion of levodopa to 3-O-methyldopa (3-OMD), a potentially harmful metabolite of levodopa.