CompletedNot Applicable

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

Germany36 participantsStarted 2025-04-28

Plain-language 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.

Who can participate

Age range

18 Years – 40 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

. individuals of both biological sexes, assigned as women or men at birth
. age: ≥ 18 and ≤ 40 years
. possesses the ability to understand the study purpose and design
. contractually capable and provides signed informed consent form
. in good general health or with mild and/or well-managed conditions such as allergies, asthma, hypertension or orthopedic diseases
. taking no more than three chronic medications
. individuals classified as either extensive metabolizers (EM) or poor metabolizers (PM) based on their CYP2D6 genotype:

Exclusion criteria

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Yohimbine plasma concentration expressed as area under the curve (AUC₀-₂₄h) - arm 1 vs. arm 3

Timeframe: 24 hours

Yohimbine plasma concentration expressed as area under the curve (AUC₀-₂₄h) - arm 1 vs. arm 2

Timeframe: 24 hours

Yohimbine plasma concentration expressed as area under the curve (AUC₀-₂₄h) - arm 3 vs. arm 4

Timeframe: 24 hours

Trial details

NCT IDNCT06939608

SponsorUniversity Medicine Greifswald

Sponsor typeOTHER

Study typeINTERVENTIONAL

Primary completion2025-10-10

View on ClinicalTrials.gov More Pharmacokinetic Study in Healthy Volunteers trials

Plain-language summary

Who can participate

Age range

18 Years – 40 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

. individuals of both biological sexes, assigned as women or men at birth
. age: ≥ 18 and ≤ 40 years
. possesses the ability to understand the study purpose and design
. contractually capable and provides signed informed consent form
. in good general health or with mild and/or well-managed conditions such as allergies, asthma, hypertension or orthopedic diseases
. taking no more than three chronic medications
. individuals classified as either extensive metabolizers (EM) or poor metabolizers (PM) based on their CYP2D6 genotype:

Exclusion criteria

What they're measuring

Yohimbine plasma concentration expressed as area under the curve (AUC₀-₂₄h) - arm 1 vs. arm 3

Timeframe: 24 hours

Yohimbine plasma concentration expressed as area under the curve (AUC₀-₂₄h) - arm 1 vs. arm 2

Timeframe: 24 hours

Yohimbine plasma concentration expressed as area under the curve (AUC₀-₂₄h) - arm 3 vs. arm 4

Timeframe: 24 hours