Actively Recruiting
Interaction of CYP2B6 Genotype and Efavirenz With Methadone and Tizanidine PK
Led by Indiana University · Updated on 2026-02-12
60
Participants Needed
1
Research Sites
131 weeks
Total Duration
On this page
Sponsors
I
Indiana University
Lead Sponsor
N
National Institute of General Medical Sciences (NIGMS)
Collaborating Sponsor
AI-Summary
What this Trial Is About
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).
CONDITIONS
Official Title
Interaction of CYP2B6 Genotype and Efavirenz With Methadone and Tizanidine PK
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Male or female volunteers between 18 and 65 years old
- Healthy without significant medical conditions as confirmed by medical history, lab tests, vital signs, and EKG within 6 weeks before starting
- Able and willing to avoid medications and supplements that affect study drugs for 2 weeks before and throughout the study
- Non-smokers or willing to stop smoking and using tobacco or marijuana at least 2 weeks before and during the study
- Willing to commit the required time for the study
You will not qualify if you...
- Underweight (less than 50 kg) or overweight with BMI over 32
- Abnormal lab results or EKG readings
- History of allergy or intolerance to efavirenz, tizanidine, or methadone
- Low hemoglobin (below 13.4 gm/dL for males, 12 gm/dL for females)
- Positive pregnancy test or unwillingness to use effective birth control if sexually active
- Night shift workers
- Significant heart, liver, or kidney disease
- History or current seizures
- History or current mental illness, including depression, anxiety, or suicidality
- Digestive disorders that affect drug absorption
- HIV infection or high risk for HIV
- Regularly drinking more than two alcoholic drinks per day without willingness to stop
- Unable or unwilling to stop using tobacco, marijuana, or drugs of abuse
- Systolic blood pressure below 70 mm Hg
- Participation in recent research involving intensive blood sampling or recent blood donation
- Taking medications or supplements that interfere with study drug metabolism and unwilling to stop
- Employees or students supervised by study investigators
- Unable to understand study risks and requirements
- Unable to follow study rules or commit required time
AI-Screening
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Trial Site Locations
Total: 1 location
1
Indiana University School of Medicine
Indianapolis, Indiana, United States, 46202
Actively Recruiting
Research Team
Z
Zeruesenay Desta, PhD
CONTACT
A
Abi Colwell
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NON_RANDOMIZED
Model
SEQUENTIAL
Primary Purpose
BASIC_SCIENCE
Number of Arms
2
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