A Study of [14C]Ulonivirine ([14C]MK-8507) in Healthy Adults (MK-8507-006)

A Study to Investigate the Absorption, Metabolism, and Excretion of [14C]Ulonivirine in Healthy Adults

The goal of this study is to learn how [14C]ulonivirine moves through a healthy person's body over time. Researchers will study how [14C]ulonivirine is absorbed by the body, broken down by the body, and how it leaves the body.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Drug: [14C]Ulonivirine

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Phase 1

Contacts and Locations

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53704
      • Fortea CRU Madison (Site 002)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Key Inclusion Criteria include but are not limited to:

• Is in good health
• Has a body mass index (BMI) of 18 to 32 kg/m^2

Key Exclusion Criteria include but are not limited to:

• Has a history of cancer
• Has positive tests for hepatitis B surface antigen, hepatitis C antibodies or human immunodeficiency virus antibody

Study Plan

How is the study designed?

Design Details

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

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: [14C]Ulonivirine; All participants receive a single oral dose of [14C]ulonivirine on Day 1.	Drug: [14C]Ulonivirine; Oral Solution; Other Names: [14C]ULO; [14C]MK-8507

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cumulative Percentage of Total Radioactivity Recovered (FE) from Urine and Feces	Urine and fecal samples will be collected to determine the cumulative percentage of radioactivity recovered from both urine and feces.	At designated timepoints (up to approximately 5 weeks postdose)
FE from Urine	Urine samples will be collected to determine the percent of total radioactivity recovered from urine.	At designated timepoints (up to approximately 5 weeks postdose)
FE from Feces	Fecal samples will be collected to determine the percent of total radioactivity recovered from feces.	At designated timepoints (up to approximately 5 weeks postdose)
Cumulative Amount of Radioactivity Recovered from Urine	Urine samples will be collected to determine the cumulative amount of radioactivity recovered from urine.	At designated timepoints (up to approximately 5 weeks postdose)
Percent of Total Radioactive Dose Recovered from Urine	Urine samples will be collected to determine the percent of the total radioactive dose recovered from urine.	At designated timepoints (up to approximately 5 weeks postdose)
Cumulative Amount of Radioactivity Recovered from Feces	Fecal samples will be collected to determine the cumulative amount of radioactivity recovered from feces.	At designated timepoints (up to approximately 5 weeks postdose)
Percent of Total Radioactive Dose Recovered from Feces	Fecal samples will be collected to determine the percent of the total radioactive dose recovered from feces.	At designated timepoints (up to approximately 5 weeks postdose)
Plasma Ulonivirine: Area Under the Concentration-Time Curve from Time 0 to Time of the Last Concentration (AUC0-last)	Plasma samples will be collected to determine the AUC0-last of ulonivirine.	At designated timepoints (up to approximately 2 weeks postdose)
Plasma Ulonivirine: Area Under the Concentration-Time Curve from Time 0 Extrapolated to Infinity (AUC0-inf)	Plasma samples will be collected to determine the AUC0-inf of ulonivirine.	At designated timepoints (up to approximately 2 weeks postdose)
Plasma Ulonivirine: Maximum Observed Concentration (Cmax)	Plasma samples will be collected to determine the Cmax of ulonivirine.	At designated timepoints (up to approximately 2 weeks postdose)
Plasma Ulonivirine: Concentration at 168 Hours Postdose (C168)	Plasma samples will be collected to determine the C168 of ulonivirine.	At approximately 1 week postdose
Plasma Ulonivirine: Terminal Half-life (t1/2)	Plasma samples will be collected to determine the t1/2 of ulonivirine.	At designated timepoints (up to approximately 2 weeks postdose)
Plasma Ulonivirine: Time of Maximum Observed Concentration (Tmax)	Plasma samples will be collected to determine the Tmax of ulonivirine.	At designated timepoints (up to approximately 2 weeks postdose)
Ratio of Ulonivirine to Total Plasma Radioactivity: AUC0-last (ulonivirine)/ AUC0-last (total radioactivity)	Plasma samples will be collected to determine the ratio of ulonivirine to total plasma radioactivity: AUC0-last (ulonivirine)/ AUC0-last (total radioactivity)	At designated timepoints (up to approximately 5 weeks postdose)
Plasma Total Radioactivity: AUC0-last	Plasma samples will be collected to determine the AUC0-last of total radioactivity.	At designated timepoints (up to approximately 5 weeks postdose)
Plasma Total Radioactivity: AUC0-inf	Plasma samples will be collected to determine the AUC0-inf of total radioactivity.	At designated timepoints (up to approximately 5 weeks postdose)
Plasma Total Radioactivity: Cmax	Plasma samples will be collected to determine the Cmax of total radioactivity.	At designated timepoints (up to approximately 5 weeks postdose)
Plasma Total Radioactivity: C168	Plasma samples will be collected to determine the C168 of total radioactivity.	At approximately 1 week postdose
Plasma Total Radioactivity: t1/2	Plasma samples will be collected to determine the t1/2 of total radioactivity.	At designated timepoints (up to approximately 5 weeks postdose)
Plasma Total Radioactivity: Tmax	Plasma samples will be collected to determine the Tmax of total radioactivity.	At designated timepoints (up to approximately 5 weeks postdose)
Total Number of Metabolites in Plasma that Represent at least 10% of the Dose of Radioactivity	Plasma samples will be collected at pre-specified timepoints and used to determine the total number of metabolites that represent at least 10% of the dose of radioactivity. Metabolites will be determined using liquid scintillation and high-resolution mass spectrometry.	At designated timepoints (up to approximately 5 weeks postdose)
Total Number of Metabolites in Urine that Represent at least 10% of the Dose of Radioactivity	Urine samples will be collected at pre-specified timepoints and used to determine the total number of metabolites that represent at least 10% of the dose of radioactivity. Metabolites will be determined using liquid scintillation and high-resolution mass spectrometry.	At designated timepoints (up to approximately 5 weeks postdose)
Total Number of Metabolites in Feces that Represent at least 10% of the Dose of Radioactivity	Fecal samples will be collected at pre-specified timepoints and used to determine the total number of metabolites that represent at least 10% of the dose of radioactivity. Metabolites will be determined using liquid scintillation and high-resolution mass spectrometry.	At designated timepoints (up to approximately 5 weeks postdose)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants Who Experience an Adverse Event (AE)	An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of the study intervention, whether or not considered related to the study intervention.	Up to approximately 5 weeks
Number of Participants Who Discontinue the Study Due to an AE	An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of the study intervention, whether or not considered related to the study intervention.	Up to approximately 5 weeks

Collaborators and Investigators

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

Publications and helpful links

Helpful Links

• Merck Clinical Trials Information

Study record dates

Study Major Dates

• Study Start (Actual): September 17, 2025
• Primary Completion (Actual): November 11, 2025
• Study Completion (Actual): November 11, 2025

Study Registration Dates

• First Submitted: December 31, 2025
• First Submitted That Met QC Criteria: December 31, 2025
• First Posted (Estimated): January 12, 2026

Study Record Updates

• Last Update Posted (Estimated): January 12, 2026
• Last Update Submitted That Met QC Criteria: December 31, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: 8507-006; MK-8507-006 (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