The purpose of this study is to determine the safety, efficacy and pharmacokinetics following administration of CVT-301 in treatment of "off" episodes in Parkinson's Disease patients.

Treatment options for patients with motor response fluctuations are limited. Most commonly, "off" episodes are managed by adjusting the dose interval of their standard oral medications or by self-administration of unscheduled doses of oral Parkinson's medication. Due to the variability in levodopa absorption following oral dosing, resumption of motor function is unreliable and may be delayed for an hour or more. CVT-301 delivers levodopa using a simple inhaler, resulting in rapid increases in levodopa blood levels and is expected to result in rapid restoration in motor function for patients experiencing "off" episodes.

Inclusion Criteria:

• Idiopathic Parkinson's Disease (PD) diagnosed between the ages of 30 and 80 years;
• Hoehn and Yahr Stage 1-3 in an "on" state;
• Require levodopa-containing medication regimen at least 4 times during the waking day;
• Experience motor fluctuations with a minimum of 2 hours of average daily "off" time per waking day (excluding early morning "off" time) and demonstrate levodopa responsiveness;
• Are on stable PD medication regimen.

Exclusion Criteria:

• Pregnant or lactating females;
• Previous surgery for PD or plan to have stereotactic surgery during the study period;
• History of psychotic symptoms requiring treatment, or suicide ideation or attempt within last year;
• Adequate lung function as measured by spirometry;
• Any significant condition, severe concurrent disease, abnormality or finding that would make patients unsuitable or may compromise patient safety.