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A Study of Ulonivirine (MK-8507) and Methadone in Healthy Volunteers (MK-8507-019)

A Clinical Trial to Study the Effect of a Single Dose of Ulonivirine on the Pharmacokinetics of Methadone

Who can join

Ages 18 to 65 · All sexes · Healthy volunteers welcome

Inclusion Criteria

The main Inclusion Criteria include but are not limited to:

* Is in good health
* Has a body mass index (BMI) between \>18 and ≤40 kg/m\^2
* Is reliably participating in a methadone maintenance program for at least 2 months prior to Day 1 and is on a documented stable dose of methadone for at least 14 days prior to Day 1

Exclusion Criteria

The main Exclusion Criteria include but are not limited to:

* Has a history of cancer (malignancy)
* Has a history of significant multiple and/or severe allergies, or has had an anaphylactic reaction or significant intolerability to prescription or nonprescription drugs or food
* Has tested positive human immunodeficiency virus (HIV) or for a sexually transmitted infection at screening
* Is under the age of legal consent

About the study

This study is designed to determine the effect of ulonivirine (MK-8507) on methadone in the body. Participants will take methadone alone and then methadone with ulonivirine to see if ulonivirine changes how the body processes methadone.

What is being tested

• Ulonivirine (drug)
• Methadone (drug)

Sponsor: Merck Sharp & Dohme LLC · Participants: 14 · Started: Aug 17, 2026

Contact the study team

• Toll Free Number · Phone: 1-888-577-8839

Official record on ClinicalTrials.gov — NCT07595263

Locations in the U.S.

From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.