A Study to Evaluate the Efficacy and Safety of Safinamide Mesilate as Add-on Therapy to Levodopa in Parkinson's Disease Participants With Motor Fluctuation in South Korea

Inclusion Criteria

• Male or female, age greater than or equal to (>=) 19 years at the time of informed consent
• Participants who meet the clinical diagnostic criteria of Movement Disorder Society (MDS) diagnostic criteria 2015 for Parkinson's disease, have motor fluctuations with >=1.5 hours of "off" time throughout the day which is confirmed at the time of Screening, and take levodopa 3 or more times a day
• Parkinson's Disease participants who are receiving levodopa without Catechol O-methyltransferase (COMT) inhibitor and/or Monoamine oxidase-B (MAO-B) inhibitor
• Be able to maintain an accurate and complete diary with the help of a caregiver as needed, recording "on" time, "on" time with dyskinesia, "off" time, and time asleep
• Be able to provide written informed consent
• Participants whose cognitive function, at the discretion of an investigator, is at a level appropriate to participate in the clinical trial (that is., with a Global Deterioration Scale [GDS] score of 3 or less or a Clinical Dementia Rating [CDR] of 0.5 or less within 3 months prior to screening)

Exclusion Criteria

• Females who are planning for pregnancy, pregnant or breastfeeding
• Prior use of safinamide
• If participants have previously taken medication such as COMT inhibitor and/or MAO-B inhibitor, they have to take appropriate wash-out period for each medication (3 days for COMT inhibitor; 14 days for MAO-B inhibitor)
• Use of medications for depression or psychosis within 5 weeks prior to screening
• History of allergic response to levodopa, or other anti-Parkinsonian agents
• Hypersensitivity or contraindications to MAO-B inhibitors
• Confirmed ophthalmologic history including any of the following conditions: albino participants, family history of hereditary retinal disease, progressive and/or severe diminution of visual acuity (that is, 20/70 on Snellen Chart), retinitis pigmentosa, retinal pigmentation due to any cause, any active retinopathy or ocular inflammation (uveitis), or diabetic retinopathy
• Participants who did not consent to having at least 7 days of washout period prior to visit 2, if known to take narcotic analgesics 7 days prior to screening visit (example, pethidine hydrochloride-containing products, tramadol hydrochloride, or tapentadol hydrochloride)
• History of serotonergic medications administration (example, tricyclic antidepressants, tetracyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-noradrenaline reuptake inhibitors, selective noradrenaline reuptake inhibitor, or noradrenergic and serotonergic antidepressant) within 5 weeks prior to screening visit
• Administering central nervous system stimulants (example, methylphenidate hydrochloride, lisdexamfetamine mesilate)
• Administering dextromethorphan
• Participants with clinically significant liver function abnormalities defined as greater than (>) 1.5 times of the upper limit of the normal range of total bilirubin or >3 times of the upper limit of the normal range of Alanine Aminotransferase (ALT) or Aspartate Aminotransferase (AST); re-examination and re-screening are allowed once within the screening period
• Have a history of hypersensitivity to any of the ingredients of the product
• Currently enrolled in another clinical trial or used any investigational drug/biologics or device within 30 days or 5*the half-life, whichever is longer, preceding informed consent