Entacapone, sold under the brand name Comtan among others, 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 a selective and reversible inhibitor of the enzyme catechol-O-methyltransferase (COMT). When taken together with levodopa (L-DOPA) and carbidopa, entacapone stops COMT from breaking down levodopa, resulting in an overall increase of levodopa remaining in the brain and body. Entacapone does not cross into the brain and hence does not inhibit COMT there.

Carbidopa/levodopa/entacapone (Stalevo), a medication developed by Orion Pharma and marketed by Novartis, is a single tablet formulation that contains levodopa, carbidopa, and entacapone.

Entacapone is used in addition to levodopa and carbidopa for people with Parkinson's disease to treat the signs and symptoms of end-of-dose "wearing-off." "Wearing-off" is characterized by the re-appearance of both motor and non-motor symptoms of Parkinson's disease occurring towards the end of a previous levodopa and carbidopa dose. In clinical trials, entacapone has not been shown to slow progression or reverse Parkinson's disease.

Entacapone is an orally active drug that can be taken with or without food.

Pregnancy category C: risk is not ruled out.

Although there have been animal studies that showed that entacapone was excreted into maternal rat milk, there have been no studies with human breast milk. Caution is advised for mothers taking entacapone while breastfeeding or during pregnancy.

Entacapone safety and efficacy have not been assessed in infants or children.