Efficacy and Safety Proof of Concept Study in Patients With Parkinson's Disease and End-of-dose Motor Fluctuations

Inclusion Criteria: * Written informed consent (IC) obtained. * Male or female patients with idiopathic PD according to the United Kingdom brain bank criteria with end-of-dose -motor fluctuations. * Hoehn and Yahr stage 2-4 performed during the on state. * An average of 3.0 hours of off time, with a minimum of 0.5 hours of off time on each day (using PD home diary \[hereafter diary\]) on 3 consecutive days before the decision of entry. * Treatment with 3-8 daily doses of levodopa/dopa decarboxylase inhibitor (DDCI) with entacapone (either levodopa/DDCI combined with Comtess®/Comtan® or as Stalevo®) or without entacapone, including daily use of soluble levodopa formulation, with a total daily levodopa dose in the range of 400-1400 mg. One evening dose of controlled-release formulation of levodopa/DDCI is allowed providing that it is included in the total daily levodopa dose in the range of 400-1400 mg mentioned above. Use of additional soluble levodopa formulations as rescue treatment, such as Madopar LT or Quick, up to a maximum of 4 doses per week is allowed; however, its use should be avoided on days during which PD status (diary) is recorded. The levodopa dose from these rescue soluble levodopa formulations is not included in the range of total daily dose of levodopa indicated above. * Unchanged levodopa/DDCI with or without entacapone and other antiparkinsonian medication (dopamine agonists, monoamine oxidase \[MAO\] B inhibitor, amantadine and/or anticholinergics with doses recommended by the manufacturer), if any, for at least 4 weeks prior to the screening visit. * Age of 30 years or above. Exclusion Criteria: * Secondary or atypical parkinsonism. * Current use of tolcapone (within 6 weeks prior to the first treatment period). * Previous tolerability problems with entacapone or tolcapone. * Concomitant treatment with apomorphine, MAO-A inhibitors or non-selective MAO inhibitors. * Concomitant treatment with drugs having antidopaminergic action including alpha-methyldopa, reserpine and antipsychotic drugs (also dopamine D2 receptor blocking antiemetics except domperidone). As an exception to the prohibition of use of antipsychotic drugs, 1 evening dose of an atypical antipsychotic is allowed. * Severe dyskinesias as judged by the investigator; however, mild to moderate dyskinesia not significantly affecting patient's activities of daily living is allowed. * Currently active hallucinations. * Severe orthostatic hypotension as judged by the investigator. * Current dementia (Mini-Mental State Examination \[MMSE\] score \< 24). * Problematic impulse control disorders (ICD) such as pathological gambling, hypersexuality or compulsive shopping within 6 months prior to the screening visit. * History of neuroleptic malignant syndrome (NMS) and/or non-traumatic (drug-induced) rhabdomyolysis. * Past or current treatment with deep brain stimulation (DBS) or other surgical treatment for PD. * Narrow-angle glaucoma or pheochromocytoma. * Any active malignant cancer. * Patients with pre-planned elective surgery that is likely to change or impact on the control of PD symptoms, or involve hospitalisation. * Failure to demonstrate acceptable/appropriate use of the diary, despite adequate training, during the screening visit or other separate training sessions during the screening period.