Levodopa and benserazide

1. A patient given levodopa and benserazide. The patient experiences bradykinesia and this improves after thirty minutes. Explain why Levodopa alone can cause side effects and not effective. Also explain the phenomena occuring in the patient (suggest a clinical approach)

2. Apriprazole is used to treat the symptom. Describe the pharmacological difference between haloperidol and apriprazole .