Entacapone (INN) is a medication commonly used in combination with other medications for the treatment of Parkinson's disease. Entacapone together with levodopa and carbidopa allows levodopa to have a longer effect in the brain and reduces Parkinson’s disease signs and symptoms for a greater length of time than levodopa and carbidopa therapy alone. Entacapone is known as a selective and reversible inhibitor of the enzyme catechol-O-methyltransferase (COMT). When taken together with levodopa (L-DOPA) and carbidopa, entacapone stops catechol-O-methyltransferase from breaking down and metabolizing levodopa, resulting in an overall increase of levodopa remaining in the brain and body. Entacapone is developed by Orion Pharma and marketed by Novartis under the trade name Comtan. Stalevo, another medication developed by Orion Pharma and marketed by Novartis, is a single tablet formulation that contains levodopa, carbidopa, and entacapone.