Gastrointestinal Dopamine Decarboxylase and Levodopa Pharmacokinetics

NCT07793461 | Not Yet Recruiting Phase 4 FDA Drug

• 2 other identifiers: 2026P000721K23DK144718
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Parkinson's Disease

Keywords

parkinson's disease; levodopa; AADC

Outcome Measures

Primary Outcomes (1)

• 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.

  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

  0-4 hours after oral levodopa ingestion

Study Arms (2)

Elevated AADC

EXPERIMENTAL

Participants will be administered a single dose of levodopa at the start of the study period

Drug: Levodopa (L-dopa)

Non-elevated AADC

EXPERIMENTAL

Participants will be administered a single dose of levodopa at the start of the study period

Drug: Levodopa (L-dopa)

Interventions

Levodopa (L-dopa) DRUG

levodopa will be administered to all participants in this single arm study

Elevated AADC; Non-elevated AADC

Eligibility Criteria

• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Parkinson's disease
• Gastric biopsies previously obtained during clinically-indicated EGD procedure
• Taking dopamine replacement therapy currently

You may not qualify if:

• No history of Parkinson's disease

Sponsors & Collaborators

• Beth Israel Deaconess Medical Center: lead
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): collaborator

Study Sites (1)

Beth Israel Deaconess Medical Center

Boston, Massachusetts, 02215, United States

Location

MeSH Terms

Conditions

Parkinson Disease

Interventions

Levodopa

Condition Hierarchy (Ancestors)

Parkinsonian Disorders; Basal Ganglia Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Movement Disorders; Synucleinopathies; Neurodegenerative Diseases

Intervention Hierarchy (Ancestors)

Dihydroxyphenylalanine; Catecholamines; Amines; Organic Chemicals; Catechols; Phenols; Benzene Derivatives; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Phenylalanine; Amino Acids, Aromatic; Amino Acids, Cyclic; Amino Acids; Amino Acids, Peptides, and Proteins; Tyrosine

Central Study Contacts

Trisha S Pasricha, MD, MPH

CONTACT

(617) 754-8888; tpasrich@bidmc.harvard.edu

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor of Medicine

Study Record Dates

• First Submitted: August 26, 2026
• First Posted: August 28, 2026
• Study Start (Estimated): July 1, 2027
• Primary Completion (Estimated): July 1, 2030
• Study Completion (Estimated): December 1, 2030
• Last Updated: August 28, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)