Safety, Tolerability, PK and PD Study of Neu-120 in the Treatment of Levodopa-induced Dyskinesia

Inclusion Criteria: * Male and female patients aged 30-80 years old (both ages included). * Use of adequate and effective birth control measures (not including the rhythm method) during the study period and up to 3 months after the end of study in men and women of child-bearing potential or within two years of menopause (these women will perform a urine pregnancy test at the screening visit) * Idiopathic Parkinson Disease (UK PD Society Brain Bank Clinical Diagnosis Criteria) diagnosed for at least 3 years. * Hoehn and Yahr "ON" time (good medication response) stage II-III. * Treatment with levodopa at an optimized dose alone or with dopamine agonists, MAO-B inhibitors or COMT inhibitors that are stable for at least 4 weeks prior to visit 1 * Use of hypnotics, sedatives, beta-blockers, anxiolytics and antidepressant only if stable for at least 4 weeks prior to visit 1. * A minimal baseline Levodopa induced dyskinesia score of 2 or more on question 32 (dyskinesias present during more than 25% of the waking day); a score of 2 or more on question 33 of UPDRS (severely disabling dyskinesias) Part IV (historical information). * A minimal basal level of motor fluctuations of 25% or more cumulative hours of OFF time every day during waking hours on the UPDRS Part IV (a minimal score of 1 on question 39 of UPDRS, historical information). * Patients have at least 33% motor improvement in response to their levodopa challenge dose based on UPDRS motor score (Part III) at visit 1. * Patients experiencing peak-dose dyskinesia with a score of at least 2 on 2 or more (≥2) areas (a score of at least 4) on the modified AIMS scale in response to their levodopa challenge dose at visit 1. * Patients must be in good general health as determined by medical history, physical examination, ECG, vital signs, serum biochemistry and haematology. * Patients must have signed an informed consent form . Exclusion Criteria: * Patient has Non-idiopathic Parkinson's disease (e.g drug-induced or other form of secondary or atypical Parkinsonism). * Neuropsychiatric exclusions: dementia (Mini Mental State Exam \< 23, history or presence of psychosis (such as visual hallucinations while taking dopamine agonists), history of or current Axis I or Axis II mental disorders according to DSM-IV; severe depression (Hamilton scale \> 17). * Any clinically relevant acute or chronic diseases which could interfere with patients' safety during the trial, or expose them to undue risk, or which could interfere with the study objectives. * History or presence of gastrointestinal, hepatic, or renal disease or other condition known to interfere with the absorption, distribution, metabolism or excretion of drugs. * Pregnant or breast feeding women. * Drug abuse or history of drug abuse (including alcohol), known drug addiction. * Patients with severe postural hypotension (\> 20 % variability between standing and supine). * The following medications are forbidden for at least one month prior to visit 1 and during the course of the study: NMDA receptor antagonists (amantadine, memantine, budipine, dextromethorphan), medication with central dopaminergic antagonist activity (neuroleptics), CNS stimulants and sodium valproate (may exacerbate dyskinesias). * Hoehn and Yahr score V when OFF (wheelchair-bound). * The patient is participating in another study or has been participating in a study within the last 2 months. * History of epilepsy and seizures. * Any history of significant drug allergy. * A history of unilateral or bilateral intracranial surgical procedures for Parkinson's Disease or any cerebral neurosurgery (except if occurred before the age of 18). * History of severe pathology likely to recur during or immediately after the study. * An inability to satisfactorily discontinue any study-forbidden medication.