Microbiota Intervention to Change the Response of Parkinson's Disease

NCT03575195 | Suspended Phase 1 FDA Drug

• 1 other identifier: 17-22841
• Study Type: interventional
• Target: 86
• Locations: 1 country
• Sites: 1

Brief Summary

The clinical phenotype of Parkinson's disease (PD) is quite variable, as is the response to and side effects from medications. While many patients respond to carbidopa/levodopa early on, motor fluctuations and dyskinesias can become a problem as the condition progresses, causing significant impairment in function and quality of life. The gut microbiome is of increasing interest in PD, potentially contributing to pathophysiology and clinical phenotype. Furthermore, gut bacteria are capable of metabolizing levodopa, which may decrease its ability to reach the central nervous system and could explain the variable effect seen clinically. Altering the population of drug-metabolizing bacteria could improve the clinical symptoms of PD and the benefit seen with medications. The investigators hypothesize that the gut microbiome in people with PD correlates with their phenotypic characteristics, which can be improved with targeting the microbiome through dietary or therapeutic interventions. The investigators propose a two-part clinical trial. First, a cross-sectional analysis will correlate the microbiome profile with (a) the clinical phenotype of PD and (b) medication response. Second, a randomized, controlled trial, will evaluate the effect of microbiome manipulation on clinical phenotype and medication response. The investigators plan to reduce the level of bacteria through antibiotic use, resetting the potentially disadvantageous microbiome population. Outcomes will include changes in clinical symptoms, alterations in the the microbiome, and changes in serum markers of inflammation. This thorough characterization will broaden our understanding of the gut-brain axis significantly in PD in clinically relevant ways that have yet to be explored.

Conditions

Parkinson Disease

Outcome Measures

Primary Outcomes (2)

• MDS-UPDRS Part III

  The Movement Disorders Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) is a validated scale that quantifies many of the symptoms and signs of Parkinson's disease. Part III in particular focuses on the motor symptoms of Parkinson's disease through a neurologic exam. The exam is often performed when medications are held for 8-12 hours (the "OFF" state) and again when medications are given and providing therapeutic benefit (the "ON" state), and the difference between scores is calculated. The scale goes from a minimum of 0 to a maximum of 132. There is no specific cutoff, but a higher score indicates a higher severity of symptoms. The trial will examine the change in the MDS-UPDRS Part III both OFF and ON medication after the intervention.

  Two weeks

• Percent of OFF time according to home motor diaries

  Patients with Parkinson's disease often have times where levodopa is providing therapeutic benefit and times when it is not. "OFF" time indicates the times of day where levodopa therapy is not providing therapeutic benefit. An outcome of the trial will be the change in medication OFF time that the participant experiences at home, according to motor diaries.

  Two weeks

Study Arms (2)

Intervention

EXPERIMENTAL

Rifaximin

Drug: Rifaximin

Placebo

PLACEBO COMPARATOR

Matching placebo

Other: Placebo

Interventions

Rifaximin DRUG

Rifaximin 550mg orally

Intervention

Placebo OTHER

Placebo control

Placebo

Eligibility Criteria

• Age: 30 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Parkinson's disease
• Stable on levodopa therapy with fluctuations

You may not qualify if:

• Chronic gastrointestinal disease
• Recent antibiotic or probiotic therapy
• Pregnant
• Immunocompromised

Sponsors & Collaborators

• University of California, San Francisco: lead
• Nova Southeastern University: collaborator
• Gateway Institute for Brain Research: collaborator

Study Sites (1)

University of California San Francisco

San Francisco, California, 94115, United States

Location

MeSH Terms

Conditions

Parkinson Disease

Interventions

Rifaximin

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)

Rifamycins; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds; Lactams, Macrocyclic; Macrocyclic Compounds; Polycyclic Compounds

Study Officials

• Caroline Tanner, MD, PhD

  University of California, San Francisco

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 21, 2018
• First Posted: July 2, 2018
• Study Start: July 15, 2019
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): August 1, 2026
• Last Updated: September 4, 2025

Record last verified: 2025-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)