Pharmacokinetic (PK) Study of Tafenoquine in Healthy Adults

The goal of this clinical trial is to learn how people's different genetic makeups affects how their bodies convert the FDA approved drug ARAKODA (tafenoquine) to its active form. Tafenoquine is a drug that is taken to prevent malaria for people traveling to areas where there is malaria. This trial will be in healthy participants age 18-65.

Study Overview

• Status: Not yet recruiting
• Conditions: Pharmacokinetic in Normal Population
• Intervention / Treatment: Drug: Tafenoquine Oral Tablet

Detailed Description

This trial will explore the how different CYP450 2D6 phenotypes metabolize a single 300mg dose of tafenoquine. Pharmacokinetic (PK) blood and urine samples, and research samples will be obtained at specific timepoints during the 2-month study.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Early Phase 1

Contacts and Locations

• Study Contact: Name: Keely Terrillion; Phone Number: 315-464-9869; Email: trials@upstate.edu

Study Locations

• United States
  • New York
    • East Syracuse, New York, United States, 13057
      • SUNY Upstate Medical University, Upstate Global Health Institute
      • Contact: Keely Terrillion; Phone Number: 315-464-9869; Email: trials@upstate.edu
      • Principal Investigator: Michele Spring, MD

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Age 18-65 at the time of consent, weighing between 132 and 250 pounds
2. Ability and willingness to sign informed consent
3. Available for the study period
4. Willing to use contraception for the duration of the study
5. Agree not to take over the counter antioxidants, vitamin C or vitamin E, 2 weeks prior to dosing and 7 days post dosing

Exclusion Criteria:

1. Women: positive urine pregnancy test at screening or day of dosing
2. Women who are lactating or intend to become pregnant during the study period.
3. Acute or chronic clinically significant hematologic, pulmonary, cardiovascular, hepatic, or renal functional abnormality as determined by medical history, physical examination or laboratory screening.
4. History of allergic reaction to tafenoquine or primaquine.
5. Scheduled receipt of any vaccine 1 week prior to or after 4 weeks tafenoquine dosing. Routine COVID and influenza vaccination will be allowed outside of this timeframe.
6. Currently taking metformin, dofeltilide or other medication with known multidrug and toxin extrusion enzyme (MATE) metabolism.
7. Known or suspected congenital or acquired immunodeficiency; or receipt of immunomodulation therapy such as anti-cancer chemotherapy or radiation therapy.
8. Diagnosis with Bipolar Disorder or Schizophrenia, hospitalization in the past year for a mental health disorder, or any other psychiatric condition, which in the opinion of the investigator prevents the participant from participating in the study.
9. Participants with hemoglobin, Creatinine, BUN, and Albumin of grade 2 or greater. Participants with eGFR <90mL/min/1.73m2; ALT >1.5x ULN, or AST >1.5x ULN. Any exclusionary lab abnormality may be repeated once. If a repeat screening blood test is performed, only the result of the second test will be reviewed and used to determine eligibility.
10. Positive HIV, hepatitis B surface antigen or hepatitis C.
11. G6PD result not normal or < 70% activity
12. Significant screening physical examination abnormalities or chronic medical condition that in the opinion of the investigator may impact participant safety, including BMI > 35kg/m2
13. Participation (active or follow-up phase) or planned participation in another vaccine, or drug, in the 4 weeks prior to or during the trial
14. Beliefs that bar the administration of blood products or transfusions
15. Clinician discretion

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Normal Metabolizers (NM); Participants with normal CYP2D6 enzyme activity receiving a single 300 milligram (mg) dose of tafenoquine.	Drug: Tafenoquine Oral Tablet; Single, 300mg dose
Experimental: Intermediate Metabolizers (IM); Participants with decreased activity of the enzyme leading to variable effects i.e., either no effect, increased adverse effects from TQ or reduced efficacy of the drug in endemic areas due to inadequate metabolism receiving a single 300mg dose of tafenoquine.	Drug: Tafenoquine Oral Tablet; Single, 300mg dose
Experimental: Poor Metabolizers (PM); Participants with no enzyme activity at all, leading to a null phenotype and no drug metabolism, receiving a single 300mg dose of tafenoquine.	Drug: Tafenoquine Oral Tablet; Single, 300mg dose
Experimental: Ultra Metabolizers (UM); Participants with increased enzyme activity, leading to accelerated metabolism, receiving 300mg dose of tafenoquine	Drug: Tafenoquine Oral Tablet; Single, 300mg dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Tafenoquine levels in blood over time	Pre-dose, 4, 8, 12, and 24 hours (Day 2) and Days, 3, 4, 5, 6, 7, 8, 15, 22, 29, and 57.
Tafenoquine levels in urine over time	Pre-dose, total volume collected between 0-4, 4-8, 8-12, 12-24 hours and then single void collections on Days 3, 4, 5, 6, 7, 8, 15, 22, 29, 57.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Methemoglobin Levels	Methemoglobin Levels at defined PK timepoints	Pre-dose, 4, 8, 12, and 24 hours (Day 2) and Days, 3, 4, 5, 6, 7, 8, 15, 22, 29, and 57
Laboratory abnormalities	Complete Blood Count and reticulocyte count	Pre-dose, Day 4 and 15
Adverse Events		From Day 1 to Day 29
Serious Adverse Events		Day 1 to Day 57

Collaborators and Investigators

• Sponsor: State University of New York - Upstate Medical University
• Investigators: Principal Investigator: Michele Spring, MD, State University of New York - Upstate Medical University

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: January 16, 2026
• First Submitted That Met QC Criteria: January 23, 2026
• First Posted (Actual): January 28, 2026

Study Record Updates

• Last Update Posted (Actual): March 20, 2026
• Last Update Submitted That Met QC Criteria: March 18, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Pharmacokinetic; CYP2D6; Tafenoquine
• Additional Relevant MeSH Terms: tafenoquine
• Other Study ID Numbers: 2026-01-UMU; PR241374 (Other Grant/Funding Number: Congressionally Directed Medical Research Programs (CDMRP))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD that underlies the primary results in a publication.
• IPD Sharing Time Frame: IPD will be shared with the primary publication
• IPD Sharing Access Criteria: Primary IPD will be published with the primary manuscript describing the study. Requests for additional information can be requested by emailing warel@upstate.edu.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No