The pharmacokinetics of V1512 effervescent tablet has been evaluated in healthy volunteers, however not fully in PD patients. This study aims to evaluate the PK profiles in PD patients of different dosing schedules of V1512 effervescent tablet compared to the profiles after standard L-dopa/carbidopa (Sinemet) over the course of the day. Two dosing schedules have been chosen to evaluate a possible relation between dosing interval and 'ON' time, with and without associated dyskinesia. Similar dosing schedules with the comparator Sinemet are commonly employed in the treatment of fluctuating PD patients. Patients assigned to cohort 3 will also take a dose of entacapone concomitantly with each dose of V1512 or Sinemet, thereby allowing the kinetics and dynamics of.V1512 and Sinemet to be compared in the presence of COMT inhibition.