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Kinetics of Yohimbine in Humans to Explore Sex and CYP2D6 Genotype Interactions

NCT06939608 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 36

Last updated 2026-01-21

No results posted yet for this study

Summary

This study investigates the pharmacokinetics of yohimbine in women and men aged 18 to 40 years to explore sex-specific differences in CYP2D6-dependent drug metabolism. Participants will be classified by their CYP2D6 genotype into extensive metabolizers (EM) and poor metabolizers (PM), forming four distinct study arms:

Arm 1) Women, Poor Metabolizers (PM) n=13 Arm 2) Women, Extensive Metabolizers (EM) n=5 Arm 3) Men, Poor Metabolizers (PM) n=13 Arm 4) Men, Extensive Metabolizers (EM) n=5

Each study arm will receive a single oral dose of 50 µg yohimbine (2 x 1 tablets, 25 µg per tablet) and 25 mg of ¹³C₃-caffeine co-administered as a drinking solution.

The purpose of this study is:

1. To characterize the pharmacokinetics of yohimbine following a single oral dose in women and men across different CYP2D6 phenotypes.
2. To evaluate yohimbine's suitability as a reliable probe for assessing CYP2D6 activity.
3. To investigate potential interactions between CYP2D6 and CYP1A2, as well as interindividual variability in CYP1A2-dependent caffeine metabolism.

Conditions

  • Pharmacokinetic Study in Healthy Volunteers

Interventions

DIETARY_SUPPLEMENT

Yohimbine

A single oral dose of 50 µg yohimbine, administered as 2 x 1 tablets of Yohimbinum hydrochloricum D4® will be co-administered with 25 mg of ¹³C₃-caffeine as drinking solution with 240mL of still water under overnight fasting conditions. A total of 19 blood samples will be collected at defined time points (baseline; 10; 20; 30; 40; 50; 60; 70; 80; 90; 100; 110 min; 2; 3; 4; 6; 8; 10; 24 h). At each time point, 4.9 mL of blood will be drawn for plasma separation to determine yohimbine, the primary metabolite 11-OH-yohimbine and ¹³C₃-caffeine with associated CYP1A2 dependent metabolites.

OTHER

¹³C₃-caffeine

A single oral dose of 25 mg of ¹³C₃-caffeine as a drinking solution will be co-administered with yohimbine with 240 mL of still water under overnight fasting conditions. ¹³C₃-caffeine is a stable isotope-labeled standard probe for phenotyping CYP1A2 activity and assessing potential interactions between CYP2D6 and CYP1A2. Plasma concentrations of ¹³C₃-caffeine with associated CYP1A2 dependent metabolites will be measured at predefined time points, following the sampling schedule outlined for yohimbine.

Sponsors & Collaborators

  • University Medicine Greifswald

    lead OTHER

Study Design

Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Model
PARALLEL

Eligibility

Min Age
18 Years
Max Age
40 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2025-04-28
Primary Completion
2025-10-10
Completion
2025-10-10

Countries

  • Germany

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT06939608 on ClinicalTrials.gov