Additional Study Information: This study is for patients with Parkinson's disease. For most patients with Parkinsons disease, doctors use levodopa as a treatment to manage their symptoms. Levodopa pills have been used for many years to treat the symptoms of Parkinsons disease patients. However, with long-term treatment, the effectiveness of levodopa pills often lessens and can lead to OFF episodes, which includes slowness, stiffness, and tremors (shaking). There are few treatment options to help combat or manage these OFF episodes. A treatment approach that permits levodopa to be more rapidly and predictably absorbed by the body is needed to help treat the OFF episodes when they occur. CVT-301, the investigational medication under evaluation in this study, is a dry powder form of levodopa. It is inhaled through an inhaler, which allows the body to absorb the medication faster than levodopa pills, which are taken orally.Doctors believe that patients may be better able to find relief from an OFF episode using the inhaled form of levodopa when OFF symptoms start to return. The results of this study will provide more information about whether inhaled levodopa could one day be used to treat OFF episodes in Parkinsons disease patients.