First study of ADX48621 in male and female Parkinson's disease patients with levodopa-induced dyskinesia. Four weeks, double-blind, placebo-controlled dose titration from 50 mg once daily up to 100 mg three times daily, at the start of week 4. Safety and tolerability assessed by adverse events enquiry, heart rate and blood pressure, 12-lead ECG, haematology and biochemistry. Efficacy assessments include Abnormal Involuntary Movement Scale (AIMS), Unified Parkinson's Disease rating Scale (UPDRS) patient PD symptom diaries, Hospital Anxiety Depression Scale (HADS), patient and clinician global impression of change in PD and dyskinesia (PGIC and CGIC).