Randomized, Double-Blind, Active Placebo-Controlled Study of Ketamine to Treat Levodopa-Induced Dyskinesia

This Phase II trial is a prospective, double-blind, randomized, parallel trial-design with two arms. Subjects will be randomized to treatment with the investigational product (ketamine) or an active control (midazolam). The active control causes mild sedation and is employed to minimize unmasking of the test article. The study is an out-patient study. However, infusion days and days involving prolonged assessments are expected to require the subject to be onsite. Subjects will return to the site for safety and efficacy evaluations. On Day 1, PK samples will be collected near the end of Infusion 1 and post-infusion to evaluate near-steady-state blood levels in all subjects. Intensive PK sampling will be conducted in all subjects prior to, during, and a few hours after Infusion 2 (Day 5 ± 2). The primary objective of the study is to evaluate the effects of low-dose intravenous infusion of ketamine on levodopa-induced dyskinesia (LID) in patients with Parkinson's disease. All patients included in the study should meet the inclusion criteria. Half of the participants will receive ketamine, while the other half will receive active placebo (Midazolam). All participants will be assigned to either the active group or the control group randomly. During the clinical trial, both investigators and patients are double-blind except serious adverse events occurred.