LEVODOPA is converted to a chemical called dopamine (DOE pa meen) in the brain. Symptoms of Parkinson's disease may be caused by low levels of dopamine in the brain. CARBIDOPA helps prevent the breakdown of levodopa before it can reach the brain and take effect. ENTACAPONE increases levels of levodopa in the body. The combination of carbidopa, entacapone, and levodopa is used to treat Parkinson symptoms such as muscle stiffness, tremors, spasms, and poor muscle control.