Comparison of Benzhexol and Procyclidine for Tremor in Tremor-Predominant Parkinson's Disease

The goal of this clinical trial is to compare benzhexol and procyclidine for improving tremor in adults with tremor-predominant Parkinson's disease who are taking levodopa. Researchers will compare the two medicines to determine whether benzhexol provides similar improvement in tremor to procyclidine and to assess their side effects. Participants will be randomly assigned to receive either benzhexol or procyclidine in addition to their usual levodopa treatment. Motor symptoms and side effects will be assessed before treatment and at 2 weeks, 3 months, and 6 months.

Inclusion Criteria: * Diagnosed Parkinson's disease according to the Movement Disorder Society Clinical Diagnostic Criteria for Parkinson's Disease, with predominant tremor at presentation. * Hoehn and Yahr stage 1, 2, or 3. * Any gender. * Age 40 to 70 years. * Receiving levodopa/carbidopa monotherapy for Parkinson's disease, with resting tremor present. Exclusion Criteria: * Cognitive or behavioral abnormalities. * Lower urinary tract symptoms. * Benign prostatic hyperplasia. * Angle-closure glaucoma. * Cardiac disease.