Interaction of CYP2B6 Genotype and Efavirenz With Methadone and Tizanidine PK
Public ClinicalTrials.gov record NCT05789173. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Official title
Effect of CYP2B6 Genotype and Efavirenz on the Disposition and Pharmacodynamic of Methadone and Tizanidine in Healthy Volunteers
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
The main goal of this clinical study is to test how CYP2B6 genetic variations and efavirenz (cornerstone in HIV-1 therapy) dictate the disposition (PK) of CYP2B6 substrate (methadone) and PK and effect (PD) of CYP1A2 substrate (tizanidine). Specifically, the investigators will test whether efavirenz produces CYP2B6 genotype dependent unanticipated DDIs with CYP2B6 (methadone) and CYP1A2 (tizanidine), leading to lack of efficacy or increased toxicity. Healthy volunteers genotyped for CYP2B6\*6 and \*18 alleles will be grouped in to three genotype predicted phenotype groups: 20 normal metabolizer (NM) (CYP2B6\*1/\*1); 20 intermediate metabolizer (IM) (\*1/\*6, or \*1/\*18); and 20 poor metabolizer (PM) (\*6/\*6, \*6/\*18 or \*18/\*18). Each phenotype group will receive methadone and tizanidine (separated by a washout period) on two occasions: at baseline (control) and after treatment with efavirenz (600 mg/day for 17 days).
Study identification
- NCT ID
- NCT05789173
- Recruitment status
- Recruiting
- Study type
- Interventional
- Phase
- Early Phase 1
- Enrollment
- 60 participants
Conditions and interventions
Conditions
Eligibility (public fields only)
- Age range
- 18 Years to 65 Years
- Sex
- All
- Healthy volunteers
- Accepts healthy volunteers
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Oct 5, 2023
- Primary completion
- Apr 30, 2027
- Completion
- Apr 30, 2027
- Last update posted
- Aug 19, 2026
2023 – 2027
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| Indiana University School of Medicine | Indianapolis | Indiana | 46202 | Recruiting |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT05789173, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Aug 19, 2026 · Synced Sep 4, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT05789173 live on ClinicalTrials.gov.