Impact of GLP-1 Receptor Agonist Therapy on Alcohol Pharmacokinetics (TAP)

This study is to learn how the weight loss drug tirzepatide (Zepbound) changes the way a body handles alcohol. 5 participants aged 21-55 who take Zepbound will be enrolled and can expect to be on study for up to 4 weeks.

Study Overview

• Status: Not yet recruiting
• Conditions: Alcohol; GLP-1
• Intervention / Treatment: Drug: Acute Ethanol Dose

Detailed Description

Participants will:

• Arrive to study visit in a fasted state
• Provide blood, breath, and urine samples prior to intervention
• Complete baseline cognitive assessments
• Self-administer the intervention (time 0), followed by breakfast (time 30 minutes)
• Complete subjective and cognitive assessments throughout treatment visit
• Provide blood, breath, and urine samples throughout treatment visit
• Consume lunch 260 minutes after dosing
• Complete study visit at 360 minutes
• Complete a final study survey

Primary Objective: Characterize the pharmacokinetics of ethanol in participants receiving maintenance Glucagon-like peptide-1 (GLP-1) receptor agonist (RA) therapy (tirzepatide).

Secondary Objectives:

- Determine the effects of GLP-1 RA therapy on alcohol-induced impairment, as measured by

• objective performance
• subjective impairment assessments
• risk perception

Correlative Objectives

• Define the exposure-response relationship between biological alcohol concentrations (breath and blood) and functional impairment to determine if Primary Objective
• Characterize the pharmacokinetics of ethanol in participants receiving maintenance GLP-1 RA therapy (tirzepatide).

• Study Type: Interventional
• Enrollment (Estimated): 5
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Heather Barkholtz, PhD; Phone Number: 608-890-1967; Email: hbarkholtz@wisc.edu
• Study Contact Backup: Name: Michael Chen, MD; Email: michael.chen@fammed.wisc.edu

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53792
      • University of Wisconsin

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• At least 21 years of age, no older than 55 years of age
• BMI 30-45 kg/m2
• Taking stable dose of prescribed, branded tirzepatide for at least 28 days
• Self-reported regular alcohol consumption
• Good mental health as determined by self-reported responses to the Psychopathology Screener and review by Study Physician as necessary
• Absence of any major medical, cardiovascular, endocrine, and neurological condition as determined by self-reported responses to the Medical History Screener
• In possession of a valid drivers' license with at least two years of driving experience
• English-speaking (able to provide consent and complete questionnaires)
• Written Informed Consent

Exclusion Criteria:

• AUDIT score of >8 requires Study Physician review
• Use of compounded GLP-1 RA
• History of or current substance use disorder as determined by self-reported responses to the Internalizing, Externalizing, and Substance Use Disorder Screener, Drug Use Disorders Identification Test, Alcohol Use Disorder Identification Test
• Pregnancy or lactation (pregnancy test, if needed)
• Use of medications that may impact cognitive ability or potentiate alcohol (e.g., mood stabilizers, sedatives)
• Use of medications that are known to significantly delay gastric emptying as determined by Study Physician
• History of pancreatitis, severe gastroparesis, or personal or family history of medullary thyroid or multiple endocrine neoplasia syndrome type 2

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: Healthy adults on Tirzepatide; Participants will complete a screening and enrollment visit, one study visit, and a follow-up correspondence over the course of approximately 4 weeks.	Drug: Acute Ethanol Dose; Time 0, participants will self-administer an oral ethanol beverage (vodka and sugar-free cherry Kool aid) calculated to reach a peak Breath Alcohol Concentration (BrAC) of 0.08 g/dL using the Widmark formula. A total time of 30 minutes will be given for completion of beverage consumption. This will be followed by a breakfast.; Other Names: vodka

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum Ethanol Concentration (Cmax)	Cmax will be determined from visual inspection of the concentration-time plots.	prior to dosing (-25 minutes), start of dosing (0 minutes), 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 240 minutes, 300 minutes, 350 minutes
Time to Maximum Ethanol Concentration (Tmax)	Tmax will be determined from visual inspection of the concentration-time plots.	prior to dosing (-25 minutes), start of dosing (0 minutes), 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 240 minutes, 300 minutes, 350 minutes
Ethanol Elimination Rate: Blood samples	Data derived from blood samples.	prior to dosing (-25 minutes), start of dosing (0 minutes), 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 240 minutes, 300 minutes, 350 minutes
Ethanol Elimination Rate: Breath tests	Data derived from breath alcohol test.	prior to dosing (-25 minutes), 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 240 minutes, 300 minutes, 350 minutes
Ethanol Elimination Rate: Urine samples	Data derived from urine samples.	prior to dosing (-25 minutes), 60 minutes, 120 minutes, 180 minutes, 240 minutes, 300 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Biphasic Alcohol Effects Scale (BAES) Score	The BAES has 2 subscales: Stimulant scored from 0-70 and Sedative scored from 0-70. Higher scores indicate higher stimulant or sedative effects.	5 minutes, 35 minutes, 65 minutes, 95 minutes, 125 minutes, 185 minutes, 245 minutes, 290 minutes, 340 minutes
Risk Perception and Safety Appraisal (RPSA) Score	To quantify cognitive and affective dimensions of risk perception, participants will complete the RPSA questionnaire assessing cognitive and affective risk perception, behavioral risk willingness, metacognitive calibration, and consequence awareness. This RPSA has been designed by the study team to provide a low burden (12-item), repeatable measure of cognitive, affective, and behavioral dimensions of risk perception, and direct quantification of willingness to engage in safety sensitive behavior. Scores range from 0-100 where higher scores indicate increased risk perception.	5 minutes, 35 minutes, 65 minutes, 95 minutes, 125 minutes, 185 minutes, 245 minutes, 290 minutes, 340 minutes
Divided Attention Task (DAT)	Participants will be asked to complete a computer-based DAT on a laptop in their room. The DAT requires participants to track a moving stimulus on a computer screen while simultaneously monitoring numbers located in the corners of the screen. Participants must respond to target numbers as they appear, and the task quantifies the mean distance of the mouse cursor from the center of the target stimulus.	prior to dosing (-20 minutes), 10 minutes, 100 minutes, 220 minutes
Digital Symbol Substitution Task (DSST)	Participants will be asked to complete a computer-based DSST on a laptop in their room. The DSST asks participants to recreate patterns of various shapes presented on a computer screen using the keyboard. The total number of correct patterns are recorded within 90 seconds.	prior to dosing (-20 minutes), 10 minutes, 100 minutes, 220 minutes
Paced Serial Addition Task (PSAT)	Participants will be asked to complete a computer-based PSAT on a laptop in their room. The PSAT has participants view a string of single-digit numbers and calculate the sum of the two most recently presented numbers. The total number of correct trials out of 90 will be recorded.	prior to dosing (-20 minutes), 10 minutes, 100 minutes, 220 minutes

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison
• Investigators: Principal Investigator: Heather Barkholtz, PhD, UW School of Pharmacy; Principal Investigator: Michael Chen, MD, UW School of Medicine and Public Health

Study record dates

Study Major Dates

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

Study Registration Dates

• First Submitted: August 5, 2026
• First Submitted That Met QC Criteria: August 5, 2026
• First Posted (Actual): August 11, 2026

Study Record Updates

• Last Update Posted (Actual): August 11, 2026
• Last Update Submitted That Met QC Criteria: August 5, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 2026-1120; Protocol Version 7/20/26 (Other Identifier: UW Madison); Pharmacy | Pharmacy Practice (Other Identifier: UW Madison); ICTR TBCR Pilot Award (Other Identifier: UW Madison)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data, including transcriptions of audio-recordings of the driving simulator experiments and biological specimens, will be stored for future use. The original digital audio recordings will not be banked for future use, only the transcription documents containing only experiment-relevant words spoken by the participant will be kept. Only members of the study team will have access to the data and specimens. Prior to banking, identifiers (including linking codes) will be removed from the data and biological specimens. Since identifiers will be removed from the data and biological specimens, participants will not be able to withdraw their banked data and specimens from future research use. Data will be released only as anonymized aggregates after careful consideration and approval of one of the study PIs. No genetic testing will take place on any banked biological specimen.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes