A Study of Rifabutin and MK-4646 in Healthy Participants (MK-4646-004)

NCT07199452 | Completed Phase 1 FDA Drug

• 2 other identifiers: 4646-004MK-4646-004
• Study Type: interventional
• Target: 18
• Locations: 1 country
• Sites: 1

Brief Summary

Researchers have designed a new study medicine called MK-4646 as a new way to treat human immunodeficiency virus (HIV). Rifabutin is a medication used to treat tuberculosis (TB). Researchers want to learn about MK-4646 when taken at the same time as Rifabutin. They want to: Measure a person's blood to find out if the amount of MK-4646 in the blood is the same when MK-4646 is taken alone or with Rifabutin Learn about the safety of MK-4646 when taken alone or with Rifabutin and if people tolerate it

Conditions

Healthy

Outcome Measures

Primary Outcomes (1)

• Area Under the Concentration-time Curve from Time 0 Extrapolated to Infinity (AUC0-inf) of MK-4646 in Plasma

  Blood samples will be collected to determine the AUC0-inf of MK-4646 in plasma.

  At designated timepoints (up to approximately 3 days post dose)

Secondary Outcomes (2)

• Number of Participants Who Experience an Adverse Event (AE)

  Up to approximately 5 weeks

• Number of Participants Who Discontinue Study Treatment Due to an AE

  Up to approximately 3 weeks

Study Arms (2)

MK-4646

EXPERIMENTAL

On Period 1 Day 1, a single oral dose of MK-4646 will be administered.

Drug: MK-4646

MK-4646 with Rifabutin

EXPERIMENTAL

Rifabutin will be administered orally once daily from Period 2 Day 1 through Period 2 Day 16. A single oral dose of MK-4646 will be administered on Period 2 Day 14.

Drug: MK-4646; Drug: Rifabutin

Interventions

MK-4646 DRUG

Oral Capsule

MK-4646; MK-4646 with Rifabutin

Rifabutin DRUG

Oral Capsule

MK-4646 with Rifabutin

Eligibility Criteria

• Age: 18 Years - 55 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Is in good health
• Has a body-mass index (BMI) between 18 and 32 kg/m2

You may not qualify if:

• Has a history of clinically significant endocrine, gastrointestinal, cardiovascular, hematological, hepatic, immunological, renal, respiratory, genitourinary, or major neurological (including stroke and chronic seizures) abnormalities or diseases
• Has a history of cancer (malignancy)

Sponsors & Collaborators

• Merck Sharp & Dohme LLC: lead

Study Sites (1)

Fortea CRU Madison ( Site 0001)

Madison, Wisconsin, 53704, United States

Location

Related Links

• Merck Clinical Trials Information

MeSH Terms

Interventions

Rifabutin

Intervention Hierarchy (Ancestors)

Rifamycins; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds; Lactams, Macrocyclic; Macrocyclic Compounds; Polycyclic Compounds

Study Officials

• Medical Director

  Merck Sharp and Dohme LLC

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 22, 2025
• First Posted: September 30, 2025
• Study Start: October 28, 2025
• Primary Completion: December 27, 2025
• Study Completion: January 7, 2026
• Last Updated: January 29, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will share

Locations

US (1)