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Study identifier: NCT05789173 Synced from ClinicalTrials.gov · July 28, 2026
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Interaction of CYP2B6 Genotype and Efavirenz With Methadone and Tizanidine PK

Condition: Drug-Drug Interaction  ·  Sponsor: Indiana University

PhaseEARLY_Phase 1
Planned participants60
Who can joinAll sexes, 18 Years to 65 Years
Healthy volunteersYes

About this study

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).

This description comes directly from the study's public registry record.

Talk to the study team

Zeruesenay Desta, PhD  ·  3172742823  ·  zdesta@iu.edu

Abi Colwell  ·  317-274-2715  ·  abcolwel@iu.edu

Always discuss trial participation with your own doctor first.

Locations (1)

Indiana University School of MedicineIndianapolis, Indiana, United StatesRecruiting

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Source record: clinicaltrials.gov/study/NCT05789173