A Phase IIa Study to Assess the Safety, Tolerability, Plasma Pharmacokinetics and Efficacy of Intermittent Oral Administration of Standard Levodopa/Carbidopa vs. Semi-continuous Intra-oral Administration of Levodopa/Carbidopa in Patients With Advanced Parkinson's Disease Who Suffer Motor Fluctuations

18 PD subjects with motor fluctuations on stable doses of standard levodopa/carbidopa +/- other dopaminergic therapy who meet entry criteria and sign an Institutional Ethical Committee approved informed consent will participate in this study. The study will be conducted at the San Raffaele IRCCS in Rome, Italy.

Subjects who successfully complete the screening activities to confirm eligibility and are approved by an enrollment steering committee will be admitted to hospital on the evening of day 1 to undergo baseline evaluations. Standard oral levodopa/carbidopa (LD/CD) medication will be stopped at midnight. On day 2, a standardized low protein breakfast will be provided and treatment will be initiated with their usual dose of standard oral LD/CD. All subsequent doses will be administered at their pre-baseline dosing intervals; other anti-parkinson medications will not be stopped and will be maintained at their usual dose. If rescue therapy is required, treatment with apomorphine sc will be administered as a first preference. Plasma levels of levodopa and metabolites will be measured over the course of the ensuing 8 hours. Physicians will assess motor status (off, on without dyskinesia, or on with dyskinesia) at 30-minute intervals throughout the 8-hour observation period and perform UPDRS motor exams at 0, 2, 4, and 8 hours. Patients will then resume their standard oral LD/CD anti-parkinsonian medications (if any), which will be stopped at midnight. On day 3 subjects will receive continuous intra-oral administration of standard LD/CD at a dose equal to the total dose of standard oral LD/CD that they would normally consume over the time course of the study period. For the purposes of this study continuous intra-oral administration will refer to oral dosing at 5-10 minute intervals. To achieve this, the drug will be chopped and administered with water so that the same total dose of levodopa that would normally be taken intermittently will be divided up and administered as small doses at 5-10 minute intervals. Patients will undergo all of the same PK blood sampling as on Day 2. If the patient is taking Stalevo, a dose of entacapone will be administered at the usual time intervals that Stalevo otherwise would have been taken. Patients will then resume their standard oral LD/CD anti-parkinsonian medication (if any), which will be stopped at midnight. On Day 4 of the study subjects will receive their first LD/CD dose orally, and the balance of the total dose they would normally take over the next 8 hours by way of continuous intra-oral administration of LD/CD over the course of the 8 hour study period. If taking Stalevo, entacapone will be administered by itself at the time Stalevo would normally have been taken.

Physicians will assess motor status (off, on without dyskinesia, or on with dyskinesia) at 30-minute intervals throughout the continuous intra-oral administration and perform UPDRS motor exams at 0, 2, 4, and 8 hours. At the completion of the study, patients will be discharged from the clinic on their standard medication. Patients will return on day 18 for a safety evaluation.