Comtan (Entacapone) is used with other medications (levodopa/carbidopa) to treat Parkinson's disease. Entacapone belongs to a class of drugs known as COMT inhibitors. Many people taking levodopa for Parkinson's have problems with the effects of the levodopa wearing off between scheduled doses, causing symptoms to return or worsen. Entacapone blocks a certain natural substance (COMT enzyme) that breaks down the levodopa in the body. This effect allows the levodopa to last longer in the system so that it doesn't wear off before the next dose.