A Relative Efficacy and Safety Study of OC Oral Solution for Sialorrhoea in Patients With Parkinson's Disease

Inclusion Criteria: * Diagnosis of Parkinson's Disease for at least 2 years * Patients with a score of ≥2 on the salivation section of UPDRS, item 6 * Patients Hoehn and Yahr stage must be ≤4 * under stable anti-Parkinson therapy throughout the study * Able and willing to comply with the study procedures * Able to provide and provision of a written informed consent Exclusion Criteria: * Female who is pregnant/lactating or planning to be pregnant * Must not have a form of drug-induced or atypical parkinsonism or parkinsonism with swallow problems due to other etiology * Have current uncontrolled hypertension, symptomatic postural hypotension, active Raynaud's disease or other peripheral vascular occlusive disease * Have a history or presence of hyperthyroidism, congestive heart failure, coronary heart disease, cardiac arrhythmias, tachycardia or severe bradycardia resulting from either sick sinus syndrome or AV block of 2nd or 3rd degree * Have a history of narrow angle glaucoma or shallow anterior chamber * Have a history or presence of gastrointestinal obstruction, including paralytic ileus and intestinal atony or gastrointestinal motility disorders, toxic megacolon or severe ulcerative colitis * Have a history or presence of bladder outflow obstruction or urinary retention * Patients with hepatic or renal impairment * Male with QTc \> 430 ms or female with QTc \> 450 ms ECG results at screening * Concomitant use of α2-agonist, anticholinergic medication or other medications that affect ACh levels * Have a history of alcohol or substance abuse * Any condition, including the presence of laboratory abnormalities, which places the patient at unacceptable risk to participate in the study or confounds the ability to interpret data from the study * Have a history of hypersensitivity to the investigational medicinal product or any of the excipients or to medicinal products with similar chemical structures * Have received treatment with any other investigational medicinal product in the last 6 weeks before administration of the first dose in this clinical study * Have received treatment with any medicinal product known to have a well-defined potential for toxicity to a major organ in the previous 3 months * Have a positive result of the human immunodeficiency virus (HIV) 1 and 2 test * Have problems to understand the protocol requirements, instructions and study related restrictions, the nature, scope and possible consequences of the clinical study * Are unlikely to comply with the protocol requirements, instructions and study related restrictions * Patient is the Investigator or any sub-investigator, research assistant, pharmacist, study coordinator, other staff or relative thereof directly involved in the conduct of the clinical study * Vulnerable subjects * Have any concurrent disease or condition that, in the opinion of the Investigator, would make the patient unsuitable for participation in the clinical study * Donation of 500 ml or more of blood within the last 8 weeks before start of the study and for at least 4 weeks after study completion * Have previously been enrolled in this clinical study * Vulnerable subjects