The trial focuses on Parkinson’s disease, a brain condition that causes shaking, stiffness and difficulty beginning movements. The investigational product is Inbrija, an inhalation powder that delivers the medication levodopa directly to the lungs for rapid absorption. It is compared with an oral liquid form called Madopar Quick, which also contains levodopa together with a helper substance that improves its effect. The purpose of the study is to see whether the inhaled form can produce a faster return to the “on” state, when symptoms improve, after the first morning dose.

Participants will take the assigned dose in the early morning after an overnight fast and will be observed for up to two hours. Their movement will be recorded with a wearable device that measures motor activity, referred to as a PKG monitor. The time from taking the dose until the first sign that the medication is working (the “on” state) will be recorded, as will the time the participants themselves notice improvement. After a short break, participants will receive the other medication and undergo the same observations. No additional invasive procedures are required.

In addition to the primary timing measure, the study will collect information on how participants feel about each treatment, their ability to start morning activities, and overall quality of life. Scores that assess daily movement difficulties and non‑motor symptoms will be gathered, and the wearable monitor will also track periods of slow movement (bradykinesia) and any involuntary movements. Sleep patterns may be evaluated through the same device, and all data are used to compare the two ways of delivering levodopa.