A Study to Compare Plasma Levels of Levodopa, Carbidopa and Entacapone After TRIGEL or Duodopa Infusion in PD Patients

This study evaluates the continuous addition of entacapone to infused levodopa and carbidopa on the pharmacokinetic (PK) profile in patients with advanced Parkinson's disease (PD). All patients will receive both study drugs, i.e. TRIGEL (levodopa, carbidopa, and entacapone) and Duodopa (levodopa and carbidopa), in randomized order.

Intestinal infusion of Duodopa (levodopa and carbidopa) provides faster absorption, comparable levodopa bioavailability and significantly reduced intra-patient variability in levodopa concentrations relative to oral administration. TRIGEL also contains a third ingredient, entacapone. In tablet form, entacapone is shown to improve the bioavailability of levodopa and might extend the half-life of levodopa, avoiding deep troughs in levodopa plasma levels, and providing more continuous delivery of levodopa to the brain. The intention with the study is to confirm that TRIGEL administration increases the area under the curve (AUC) for levodopa by combining levodopa, carbidopa, and entacapone and thereby lower the daily levodopa dose needed. It is expected that TRIGEL administration will result in a similar intra-patient variability in plasma levodopa concentrations as Duodopa during continuous administration.