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

June 1, 2026 updated by: Merck Sharp & Dohme LLC

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

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.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

14

Phase

  • Phase 1

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Methadone + Ulonivirine
Participants receive a stable dose of methadone orally from Day -14 through Day 16. Methadone is co-administered with one dose of oral ulonivirine on Day 2.
Drug: Ulonivirine
Oral Tablet
Other Names:
  • MK-8507
Drug: Methadone
Oral (per local guidelines)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Dose-Normalized Area Under the Plasma Concentration Time Curve From 0-24 Hours Postdose (AUC0-24) of R-Methadone
Time Frame: Up to 24 hours post-dose
The AUC0-24 of R-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized AUC0-24 of S-Methadone
Time Frame: Up to 24 hours post-dose
The AUC0-24 of S-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Dose-Normalized Maximum Plasma Concentration (Cmax) of R-Methadone
Time Frame: Up to 24 hours post-dose
The Cmax of R-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized Plasma Concentration 24 Hours Postdose (C24) of R-Methadone
Time Frame: 24 hours post-dose
The C24 of R-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
24 hours post-dose
Time to Maximum Plasma Concentration (Tmax) of R-Methadone
Time Frame: Up to 24 hours post-dose
The Tmax of R-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized Cmax of S-Methadone
Time Frame: Up to 24 hours post-dose
The Cmax of S-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized C24 of S-Methadone
Time Frame: 24 hours post-dose
The C24 of S-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
24 hours post-dose
Tmax of S-Methadone
Time Frame: Up to 24 hours post-dose
The Tmax of S-methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized AUC0-24 of Total Methadone
Time Frame: Up to 24 hours post-dose
The AUC0-24 of total methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized Cmax of Total Methadone
Time Frame: Up to 24 hours post-dose
The Cmax of total methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Dose-Normalized C24 of Total Methadone
Time Frame: 24 hours post-dose
The C24 of total methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
24 hours post-dose
Tmax of Total Methadone
Time Frame: Up to 24 hours post-dose
The Tmax of total methadone will be determined on Day 1 (methadone) and Day 2 (methadone + ulonivirine).
Up to 24 hours post-dose
Number of Participants With Adverse Events (AEs) Following Methadone + Ulonivirine Coadministration
Time Frame: Up to 16 Days
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. The number of participants experiencing an AE following coadministration of methadone and ulonivirine will be presented.
Up to 16 Days
Number of Participants Discontinuing Study Therapy Due to AEs Following Coadministration of Methadone and Ulonivirine
Time Frame: Up to 16 Days
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. The number of participants discontinuing study therapy due to an AE following coadministration of methadone and ulonivirine will be presented.
Up to 16 Days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Merck Sharp & Dohme LLC

Investigators

  • Study Director: Medical Director, Merck Sharp & Dohme LLC

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

June 30, 2026

Primary Completion (Estimated)

January 15, 2027

Study Completion (Estimated)

January 15, 2027

Study Registration Dates

First Submitted

May 12, 2026

First Submitted That Met QC Criteria

May 12, 2026

First Posted (Actual)

May 19, 2026

Study Record Updates

Last Update Posted (Actual)

June 2, 2026

Last Update Submitted That Met QC Criteria

June 1, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 8507-019
  • MK-8507-019 (Other Identifier: MSD)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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