Oral Levodopa Formulation Does Not Affect Progression of Parkinson Disease.

Objective: Motor fluctuations develop in most patients treated with carbidopa/levodopa for Parkinson disease. The continuous dopamine stimulation hypothesis suggests that longer-acting forms of levodopa might improve outcomes, but this has been inadequately tested in humans. We undertook to determine if there is any difference in symptom progression rate among patients taking immediate-release carbidopa/levodopa (IR), controlled-release carbidopa/levodopa (CR), or carbidopa/levodopa/entacapone (CLE) using standard outcome measures in a naturalistic study.