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

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
14

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Merck Sharp & Dohme LLC

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 30, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 15, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 15, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
May 12, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 12, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 19, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 2, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 1, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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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