Sustained enteral administration of levodopa increases and interrupted infusion decreases levodopa dose requirement

We placed a 60-year-old man with Parkinson's disease and marked therapeutic response fluctuations on a continuous enteral infusion of levodopa. On around-the-clock infusion, motor performance declined, although the infusion rate was progressively increased. We therefore interrupted the infusion each night. The patient could then progressively reduce levodopa intake while remaining continuously "on." Continuous infusion of levodopa downregulates, and interrupted infusion can restore, and even enhance, the sensitivity of striatal dopamine receptors.