Testing a nasal spray for times when Parkinson’s medicine wears off

Inclusion Criteria: * Male or female patients aged 30 to 85 years (inclusive); * Diagnosed with Parkinson's disease according to the Chinese Diagnostic Criteria for Parkinson's Disease (2016), with a disease duration of at least 3 years; * Patients with a Hoehn-Yahr stage rating (during "on" periods) of 1 to 3; * Demonstrates responsiveness to levodopa (≥30% improvement/decrease in UPDRS-III score (motor examination) from "off" to "on" state following morning administration of routine levodopa dose); * Patients must have no plans for conception from 2 weeks before the first dose until 1 month after the last dose, no plans to donate sperm, and agree to use highly effective contraception methods; * Patients are capable of understanding the study requirements, voluntarily provide written informed consent, and are able to complete the study in compliance with the trial protocol. Exclusion Criteria: * Individuals with motor impairments that severely affect their ability to participate in and perform study procedures; * Those exhibiting dyskinesia that significantly impacts daily functioning; * Known hypersensitivity/allergic reaction or intolerance to any component of the investigational drug; * Previous Parkinson's disease (PD) surgery (including but not limited to deep brain stimulation or brain cell transplantation) or planned PD surgery during the trial period; * History of malignancy within the past 5 years, except for adequately treated carcinoma in situ of the cervix, basal or squamous cell skin cancer, localized prostate cancer treated with radical surgery, or ductal carcinoma in situ of the breast treated with radical surgery; * History of severe psychiatric disorders within the past year, such as major depression, mania, schizophrenia, or patients with suicidal tendencies; * Patients deemed unsuitable for intranasal administration by the investigator (e.g., severe rhinitis, nasal deformities, etc.); * Those currently receiving centrally nervous system-active medications (e.g., sedatives, hypnotics, antidepressants, anxiolytics), except for those who have maintained a stable dose for at least 30 days prior to screening and can remain stable during the study; * History of orthostatic hypotension or clinically significant hypotension or orthostatic hypotension identified during screening (orthostatic hypotension is defined as a drop in systolic blood pressure ≥20 mmHg or diastolic blood pressure ≥10 mmHg within 3 minutes of standing from a supine position) * Any laboratory test during screening meeting the following criteria: Liver function: Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>3 × upper limit of normal (ULN); or total bilirubin \>2 × ULN; Renal function: Serum creatinine \>178 μmol/L;11. Pregnant or lactating females, or those with a positive pregnancy test during screening; * History of drug or alcohol abuse within the past year; * Participation in a clinical trial and use of an investigational drug within 1 month prior to screening or within 5 drug half-lives (whichever is longer); * Any other condition considered by the investigator to make the patient unsuitable for participation in the trial.