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Clinical Trials/2025-524778-41-00
2025-524778-41-00
Withdrawn
Phase 2

Oral rifaximin in patients with opioid use disorder (OUD): multicenter clinical trial on the microbiota–gut–brain axis

Fondazione Santa Lucia0 sites50 target enrollmentStarted: March 15, 2026Last updated:

Overview

Phase
Phase 2
Status
Withdrawn
Enrollment
50

Overview

Brief Summary

The primary objective is to determine whether 4 weeks of treatment with rifaximin, compared with placebo, results in measurable improvement in intestinal barrier integrity and gut-derived inflammatory signalling compared with placebo.

Study Design

Allocation
Randomized
Primary Purpose
Na
Masking
Double (Investigator, Subject)

Eligibility Criteria

Ages
18 years to 64 years (18-64 Years)
Accepts Healthy Volunteers
No

Inclusion Criteria

  • Diagnosis of OUD according to DSM‑5 criteria; patients in the early phase of withdrawal or in treatment with the intention to discontinue opioid use; age between 18 and 60 years; for female participants, not pregnant and not breastfeeding; ability to understand and sign informed consent. Patients with recent abstinence (e.g., within 1–4 weeks from last opioid use) will be preferentially included to capture the early adaptation phase, but not those in uncontrolled acute withdrawal. Patients receiving methadone maintenance treatment are eligible, provided they are on a stable dose and willing not to modify it for at least the first month of the study.

Exclusion Criteria

  • Presence of known organic gastrointestinal diseases (e.g., Crohn’s disease, ulcerative colitis, untreated celiac disease, advanced-stage liver cirrhosis, GI malignancies) that may significantly alter intestinal permeability or contraindicate biopsy; diagnosis of active chronic infection; severe uncontrolled medical conditions; active psychiatric disorders that impair cooperation; current use of antibiotics or probiotics that significantly alter the microbiota (requiring at least a 4‑week washout before the study); HIV/AIDS or immunocompromised status; known allergy or severe adverse reaction to rifaximin or to antibiotics of the rifamycin class; for women, confirmed or planned pregnancy during the study period. Concurrent participation in other interventional clinical trials; inability to comply with study procedures.

Investigators

Sponsor Class
Hospital/Clinic/Other health care facility
Responsible Party
Principal Investigator
Principal Investigator

Daniele Caprioli

Scientific

Fondazione Santa Lucia

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