Patient description: The patient is a 55-year-old man who was recently diagnosed with Parkinson's disease. He is complaining of slowness of movement and tremors. His disease is ranked as mild, Hoehn-Yahr Stage I. His past medical history is significant for hypertension and hypercholesterolemia. He lives with his wife. They have three children. He used to be active with gardening before his diagnosis. He complains of shaking and slow movement. He had difficulty entering through a door, as he was frozen and needed guidance to step in. His handwriting is getting smaller. He is offered Levodopa and Trihexyphenidyl. He is an alert and cooperative man who does not have any signs of dementia. He does not smoke or use any illicit drugs.

Clinical trial eligibility criteria: eligible ages (years): 30.0-999.0,  Parkinson's Disease The subject has given his/her written informed consent to participate in the trial. 2. The subject presents with a diagnosis of idiopathic Parkinson's disease according to the United Kingdom (UK) Parkinson's Disease Society Brain Bank Clinical Diagnosis 3. The subject is an out-patient aged 30 years or above. 4. PD subjects with a Hoehn and Yahr disease staging of II-IV (in the ON state). 5. PD subjects experiencing levodopa induced dyskinesias, specifically predictable peak-dose dyskinesia. 6. Peak-dose dyskinesia must be considered by the subject to be problematic and/or disabling. 7. Peak-dose dyskinesia must warrant medical treatment in the Investigator's opinion. 8. The subject has participated successfully in a diary-card training session. 9. In the judgment of the Investigator based on the subject's history, previous treatments, and the clinical presentation, the subject is considered as being optimally treated at screening (i.e., further adjustments of current medication will not further improve the subject's symptoms of Parkinson's disease). 10. Stable dose of PD drugs for at least 4 weeks before Screening Visit. This may levodopa dopamine agonists, c-ortho methyl transferase (COMT) inhibitors, and anticholinergics. 11. The dose of levodopa and all PD drugs used during the trial must remain unchanged throughout the trial. 12. Female subjects must be neither pregnant or breast-feeding and must lack child-bearing potential, as defined either by: 1. be either post menopausal for at least 2 years , surgically sterilised or have undergone hysterectomy, or 2. if of child bearing potential, be willing to avoid pregnancy by using an adequate method of contraception for four weeks prior to, during and four weeks after the last dose of trial medication. For the purposes of this trial, women of childbearing potential are defined as all female subjects after puberty unless they are post-menopausal for at least two years, are surgically sterile or are sexually inactive. 13. The subject shows adequate compliance with the schedule for intake of trial medication and the completion of the diaries  The subject has participated in any safinamide clinical trial before. 2. The subject is experiencing exclusively diphasic, off state, myoclonic, dystonic, or akathetic dyskinesias without peak dose dyskinesia. 3. (For female subjects) The subject is pregnant or lactating. 4. Treatment with a MAO-B inhibitor within the eight weeks prior to the screening visit. 5. Treatment with amantadine in the four weeks prior to the screening visit or budipine in the eight weeks prior to the screening visit. 6. Treatment with opioids (e.g., tramadol, meperidine derivatives), serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g. venlafaxine, duloxetine), tri or tetra-cyclic antidepressants, in the past 8 weeks prior to the screening visit. Dextromethorphan will be permitted if used for treating cough. 7. The subject has received neurosurgical intervention related to PD (e.g. deep brain stimulation, thalamotomy etc.) or is scheduled to do so during the trial period. 8. Current clinically significant gastro-intestinal, renal, hepatic, endocrine, pulmonary or cardiovascular disease, including acute gastric ulcer, hypertension that is not well controlled, asthma, chronic obstructive pulmonary disease (COPD), and unstable Type I diabetes. Subjects with a history of gastric ulcer who have not had a recent episode of acute gastritis and are not currently experiencing gastric pain will be eligible for inclusion. 9. Neoplastic disorder, which is either currently active or has been in remission for less than one year. 10. Diagnosis of HIV, or positive test for Hepatitis C antibodies, or Hepatitis B surface antigen. 11. Concomitant disease likely to interfere with trial medication (e.g. capable of altering absorption, metabolism, or elimination of the trial drug). 12. The subject has any clinically significant illness that, in the Investigator's opinion, might interfere with the subject's ability to participate in the trial. 13. Second or third-degree atrio-ventricular block or sick sinus syndrome, uncontrolled atrial fibrillation, severe or unstable angina, congestive heart failure, myocardial infarction within 3 months of the screening visit, or a significant ECG abnormality, including corrected QT interval (QTc) msec (males) or msec (females), where QTc is based on Bazett's correction method. 14. Ophthalmologic history including any of the following conditions: albino subjects, family history of hereditary retinal disease, progressive and/or severe diminution of visual acuity (i.e., 20/70), retinitis pigmentosa, retinal pigmentation due to any cause, any active retinopathy or ocular inflammation (uveitis), or diabetic retinopathy 15. The subject is suffering from any dementia or other psychiatric illness that prevents him/her from giving informed consent, i.e. Montreal Cognitive Assessment (MoCA) <23 points. 16. Signs and symptoms suggestive of transmissible spongiform encephalopathy, or family members who suffer(ed) from such. 17. Known hypersensitivity to the trial treatment(s), including placebo or other comparator drug(s). 18. The subject has legal incapacity or limited legal capacity. 19. The subject is participating in another clinical trial or has done so within the past 30 days 20. Treatment with a drug that has hepatotoxic potential, e.g., tamoxifen, within 4 weeks, or received radiation therapy or a drug with cytotoxic potential, e.g, chemotherapy, within one year prior to the screening visit. 21. Subjects with current diagnosis of substance abuse (DSM-IV) or history of alcohol or drug abuse in the past three months