How different dosing intervals affect WD-1603 levels when taken before meals in healthy adults

A Clinical Study to Assess the Effect of Different Dosing Intervals on the Multiple-Dose Pharmacokinetics of WD-1603 (25mg Carbidopa/150mg Levodopa) When Administered Before Meals in Healthy Participants

This study will test if spacing two daily doses of WD-1603 differently changes how healthy adults' bodies process the medication.

Quick facts

• Phase: Phase 1
• Study type: Interventional
• Enrollment: 12 (estimated)
• Ages: 18 Years to 55 Years
• Sex: All
• Sponsor: Shanghai WD Pharmaceutical Co., Ltd. (Industry-sponsored)
• Locations: 1 site (Shanghai)
• Trial ID: NCT07442591 on ClinicalTrials.gov

What this trial studies

This is an open-label, multiple-dose, sequential three-period pharmacokinetic study in healthy adults who will each take one WD-1603 tablet twice on three separate dosing days with up to a 7-day washout between periods. The two doses on each dosing day will be spaced at different intervals to compare how dosing timing affects blood levels. Safety and tolerability will also be monitored during and after dosing. Pharmacokinetic endpoints such as Cmax and AUC will be calculated and analyzed using log-transformed ANOVA to compare the second dose to the first dose.

Who should consider this trial

Good fit: Healthy adults aged 18 to 55 years with BMI between 18 and 27 kg/m², meeting normal screening exams and lab tests, are eligible to participate.

Not a fit: People who are pregnant, have significant medical conditions, fall outside the age or BMI limits, or who need levodopa/carbidopa for active Parkinson's symptoms are unlikely to receive direct clinical benefit from participating.

Why it matters

Potential benefit: If successful, the results could help define dosing intervals that produce steadier levodopa/carbidopa blood levels and reduce dosing-related fluctuations for people who use these medications.

How similar studies have performed: Pharmacokinetic studies of levodopa/carbidopa formulations are common and have informed dosing for Parkinson's medicines, but direct comparisons of dosing intervals for this WD-1603 formulation are novel.

Eligibility criteria

Inclusion Criteria:

* Healthy adult male or female participants aged 18 to 55 years (inclusive) at the time of signing the informed consent form (ICF).
* Body weight: male ≥ 50 kg, female ≥ 45 kg; body mass index (BMI) between 18 and 27 kg/m² (inclusive) (BMI = weight \[kg\] / height² \[m²\]).
* Medical history inquiry, physical examination, vital signs, laboratory tests (complete blood count, urinalysis, blood biochemistry, serological virology tests, coagulation function), 12-lead ECG, intraocular pressure measurement, abdominal ultrasound, and chest X-ray during the screening period are all within normal ranges or clinically insignificant if outside normal ranges.
* Participants (including their spouses or partners) have no plans for conception or for donating sperm/eggs from the time of signing the ICF (for females)/first dosing (for males) until 3 months after the last dose, and voluntarily agree to use effective non-pharmacological contraception during the trial period.
* Fully understand the trial content, procedures, and potential adverse reactions, voluntarily agree to participate, and sign the ICF before any trial-related procedures begin.
* Able to communicate well with the investigators and capable of understanding and complying with the requirements of this trial.

Exclusion Criteria:

* Allergy-prone constitution, history of allergic diseases, or known severe allergic reaction or allergy history to levodopa/carbidopa or related medications.
* Drug use within 3 months prior to screening, history of drug abuse, or positive urine drug abuse screening (morphine, methamphetamine, ketamine, methylenedioxymethamphetamine, tetrahydrocannabinol acid, cocaine).
* History of glaucoma, cancer, diabetes mellitus, bronchial asthma, or any clinically significant cardiovascular, respiratory, metabolic, renal, hepatic, gastrointestinal, hematological, dermatological, endocrine, neuropsychiatric diseases, or other significant conditions.
* Dysphagia or any condition that may affect drug absorption (e.g., gastrectomy, cholecystectomy, gastric bypass, duodenotomy, colectomy), or gastrointestinal diseases causing clinically significant symptoms such as nausea, vomiting, diarrhea, or malabsorption syndrome.
* History of orthostatic hypotension.
* Any relevant medical history, surgical history, or trauma within 3 months prior to the first dose that may affect trial safety or drug pharmacokinetics, or planned surgery during the trial period.
* Use of prescription drugs, over-the-counter medications, health products, Chinese herbal medicines, or dietary supplements within 4 weeks prior to the first dose, especially monoamine oxidase inhibitors (e.g., phenelzine, rasagiline, selegiline, brofaromine, toloxatone, isocarboxazid, etc.).
* Participation in any clinical trial and receipt of investigational drugs within 3 months prior to the first dose.
* Blood donation (including component blood) or significant blood loss (≥400 mL), blood transfusion, or use of blood products within 3 months prior to the first dose.
* Difficulty with venous access, unsuitability or unwillingness to use intravenous catheters, or history of needle/blood phobia.
* Heavy smokers or average daily cigarette consumption of more than 10 cigarettes within 3 months prior to screening.
* Alcohol consumption exceeding 21 standard units per week within 3 months prior to screening (1 standard unit contains 14g of alcohol, e.g., 360 mL of beer, 45 mL of 40% spirits, or 150 mL of wine), positive alcohol breath test, or unwillingness to abstain from alcohol from 48 hours before the first dose of each period until the completion of blood sampling for that period.
* Estimated glomerular filtration rate (eGFR) \< 90 mL/min·1.73m² during the screening period.
* During screening: systolic blood pressure \< 90 mmHg or ≥ 140 mmHg, diastolic blood pressure \< 60 mmHg or ≥ 90 mmHg, pulse rate \> 100 beats/min or \< 50 beats/min.
* History of prolonged QT interval or other clinically significant cardiac diseases, or QTcF ≥ 450 ms on ECG during screening.
* Symptoms of acute infection (e.g., influenza) or acute gastroenteritis within 2 weeks prior to screening, or history of vomiting or diarrhea within 1 week prior to screening.
* Positive for hepatitis B surface antigen (HBsAg), hepatitis C virus antibody (HCV-Ab), human immunodeficiency virus antibody (HIV-Ab), or Treponema pallidum antibody.
* Currently pregnant (including positive pregnancy test) or lactating female.
* Poor compliance as judged by the investigator, or other factors deemed unsuitable for participation in this trial.

Where this trial is running

Shanghai

• Shanghai Xuhui Central Hospital — Shanghai, China (Recruiting)

Study contacts

• Principal investigator: Yanmei Liu, Master — Shanghai Xuhui Central Hospital
• Study coordinator: Danyong Zhang, Master

Conditions Healhty; multiple-dose, open-label, pharmacokinetic