Parkinson's DiseasePhase 4NCT07793461
Gastrointestinal Dopamine Decarboxylase and Levodopa Pharmacokinetics
A Phase 4 study testing Levodopa (L-dopa) in people with Parkinson's Disease, run by Beth Israel Deaconess Medical Center at 1 site in United States.
Trial summary
The main treatment for Parkinson's disease is a medication called levodopa. Levodopa has to be absorbed from the gut and travel to the brain to work, but a naturally occurring enzyme in the lining of the stomach, called dopamine decarboxylase (AADC), can break some of it down before it ever reaches the brain. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Parkinson's Disease
- What is being tested?
- Levodopa (L-dopa)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- Jul 2027to Dec 2030
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Parkinson's disease
- Gastric biopsies previously obtained during clinically-indicated EGD procedure
- Taking dopamine replacement therapy currently
Who cannot join
- No history of Parkinson's disease
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
Beth Israel Deaconess Medical Center
Boston, Massachusetts, 02215
Louise Halbert, BA, 6176670698, lhalbert@bidmc.harvard.edu
Trisha Pasricha, MD, MPH, 6176670161, tpasrich@Bidmc.harvard.edu
About this study
The main treatment for Parkinson's disease is a medication called levodopa. Levodopa has to be absorbed from the gut and travel to the brain to work, but a naturally occurring enzyme in the lining of the stomach, called dopamine decarboxylase (AADC), can break some of it down before it ever reaches the brain. We do not yet know whether people whose stomachs have more of this enzyme absorb less of their levodopa dose, have worsened gastrointestinal (GI) symptoms associated with levodopa intake, and whether that affects how well the medication controls their movement symptoms. This research may help doctors understand why levodopa works better in some people with Parkinson's disease than others, which could help improve treatment in future.
Read the detailed description
Patients will be asked to fast overnight prior to the study visit, including holding any doses of dopamine replacement therapy that they may be prescribed, including levodopa or equivalents, and any promotility agents, including cholinesterase inhibitors or peripherally-restricted dopamine antagonists (ie. Domperidone), that may impact gastric transit.
At the start of the study visit, patients will undergo a neurological exam by a study investigator blinded to which study group the patient belongs. Exams will be performed according to the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III, a validated clinical score of motor impairment in Parkinson's disease (PD). They will also undergo a baseline blood draw (5.5 mLs) through an indwelling venous cannula in the antecubital vein. Immediately afterwards, a single oral dose of levodopa (100 mg) obtained through the BIDMC research pharmacy with a standard volume of water (100 mL). Repeat blood samples will be collected immediately after oral levodopa ingestion (T=0) and then repeated every ½ hour until T=4 hours for a total of 10 draws, including the baseline. The initial placement of indwelling venous cannula will mitigate the necessity for repeated venipuncture during the study visit. At each ½ hour interval, additionally, patients will undergo repeat MDS-UPDRS-III assessments. After the 4-hour study concludes, the patient will be allowed to consume any food they would like and can resume home medications as previously prescribed clinically. Blood samples will be centrifuged to separate plasma and immediately frozen at -80oC until analysis by an investigator blinded to which study group the patient belongs.
Separately, patients' prior clinically-obtained gastric biopsy blocks will be requested from BIDMC pathology (as otherwise discarded specimen) and stained for presence of AADC. This will not require any further time or visits from the patient themselves.
- Conditions
- Parkinson's Disease
- Being tested
- Levodopa (L-dopa)
- Keywords
- parkinson's disease, levodopa, AADC
- Medical subject headings
- Parkinson Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Levodopa (L-dopa)Drug
levodopa will be administered to all participants in this single arm study
| Study group | Role | What they receive |
|---|---|---|
| Elevated AADC | Experimental | Participants will be administered a single dose of levodopa at the start of the study period Receives: Drug: Levodopa (L-dopa) |
| Non-elevated AADC | Experimental | Participants will be administered a single dose of levodopa at the start of the study period Receives: Drug: Levodopa (L-dopa) |
What is being measured
The primary outcome is the main question the study is designed to answer.
levodopa pharmacodynamics
Peripheral levodopa levels will be assessed via blood draw to determine time (in minutes) to reach maximum concentration in the blood. Lower Tmax indicates quicker bioavailability.
Measured: 0-4 hours after oral levodopa ingestion.
Secondary outcomes (1)
The Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score
Neurological symptoms will be assessed during study period. A lower score indicates less severe symptoms.
Measured: 0-4 hours after oral levodopa ingestion
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Aug 2026
- Study startJul 2027 (estimated)
- Primary completionJul 2030 (estimated)
- Study completionDec 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Parkinson's DiseaseStudies of the same condition, open and under way.
- More trials run by Beth Israel Deaconess Medical CenterThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Beth Israel Deaconess Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Trisha Pasricha, Beth Israel Deaconess Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07793461
- Sponsor's protocol ID
- 2026P000721
- Other IDs
- K23DK144718
- Status last verified
- Aug 2026
- First submitted
- 26 Aug 2026
- Last updated
- 28 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 28 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Gastrointestinal Dopamine Decarboxylase and Levodopa Pharmacokinetics
- ClinicalTrials.gov ID
- NCT07793461
- Acronym / sponsor ID
- 2026P000721
- Conditions
- Parkinson's Disease
- Keywords
- parkinson's disease, levodopa, AADC
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Beth Israel Deaconess Medical CenterUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- Jul 2027 (estimated)
- Primary completion
- Jul 2030 (estimated)
- Study completion
- Dec 2030 (estimated)
- First posted
- 28 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The main treatment for Parkinson's disease is a medication called levodopa. Levodopa has to be absorbed from the gut and travel to the brain to work, but a naturally occurring enzyme in the lining of the stomach, called dopamine decarboxylase (AADC), can break some of it down before it ever reaches the brain. We do not yet know whether people whose stomachs have more of this enzyme absorb less of their levodopa dose, have worsened gastrointestinal (GI) symptoms associated with levodopa intake, and whether that affects how well the medication controls their movement symptoms. This research may help doctors understand why levodopa works better in some people with Parkinson's disease than others, which could help improve treatment in future.
Detailed description
Patients will be asked to fast overnight prior to the study visit, including holding any doses of dopamine replacement therapy that they may be prescribed, including levodopa or equivalents, and any promotility agents, including cholinesterase inhibitors or peripherally-restricted dopamine antagonists (ie. Domperidone), that may impact gastric transit.
At the start of the study visit, patients will undergo a neurological exam by a study investigator blinded to which study group the patient belongs. Exams will be performed according to the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III, a validated clinical score of motor impairment in Parkinson's disease (PD). They will also undergo a baseline blood draw (5.5 mLs) through an indwelling venous cannula in the antecubital vein. Immediately afterwards, a single oral dose of levodopa (100 mg) obtained through the BIDMC research pharmacy with a standard volume of water (100 mL). Repeat blood samples will be collected immediately after oral levodopa ingestion (T=0) and then repeated every ½ hour until T=4 hours for a total of 10 draws, including the baseline. The initial placement of indwelling venous cannula will mitigate the necessity for repeated venipuncture during the study visit. At each ½ hour interval, additionally, patients will undergo repeat MDS-UPDRS-III assessments. After the 4-hour study concludes, the patient will be allowed to consume any food they would like and can resume home medications as previously prescribed clinically. Blood samples will be centrifuged to separate plasma and immediately frozen at -80oC until analysis by an investigator blinded to which study group the patient belongs.
Separately, patients' prior clinically-obtained gastric biopsy blocks will be requested from BIDMC pathology (as otherwise discarded specimen) and stained for presence of AADC. This will not require any further time or visits from the patient themselves.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Elevated AADC | Experimental | Drug: Levodopa (L-dopa)Participants will be administered a single dose of levodopa at the start of the study period |
| Non-elevated AADC | Experimental | Drug: Levodopa (L-dopa)Participants will be administered a single dose of levodopa at the start of the study period |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (3 listed)
- Parkinson's disease
- Gastric biopsies previously obtained during clinically-indicated EGD procedure
- Taking dopamine replacement therapy currently
Key exclusion criteria (1 listed)
- No history of Parkinson's disease
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Levodopa (L-dopa)levodopa will be administered to all participants in this single arm study | Drug | Elevated AADC, Non-elevated AADC |
Primary outcome
levodopa pharmacodynamics
Time frame: 0-4 hours after oral levodopa ingestion.
Peripheral levodopa levels will be assessed via blood draw to determine time (in minutes) to reach maximum concentration in the blood. Lower Tmax indicates quicker bioavailability.
1 secondary outcome
The Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score
Time frame: 0-4 hours after oral levodopa ingestion
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Aug 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Levodopa (L-dopa) in people with Parkinson's Disease, run by Beth Israel Deaconess Medical Center at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 28 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Trisha S Pasricha, MD, MPH ((617) 754-8888, tpasrich@bidmc.harvard.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
levodopa pharmacodynamics (time frame: 0-4 hours after oral levodopa ingestion.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Aug 2026.