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NCT Number: NCT07595263

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

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.

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Key information

Conditions

Healthy

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Ulonivirine

Drug

Oral Tablet

Other names: MK-8507

Methadone

Drug

Oral (per local guidelines)

Primary outcomes

  1. 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).

  2. 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).

Secondary outcomes

  1. 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).

  2. 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).

  3. 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).

  4. 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).

  5. 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).

  6. 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).

  7. 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).

  8. 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).

  9. 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).

  10. 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).

  11. 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.

  12. 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.

Sponsors and collaborators

Lead sponsor

Merck Sharp & Dohme LLC

Industry

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
May 19, 2026
Registry last updated
Jun 23, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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