Study on the Effects of Rifaximin on Stress and Fear Responses in Healthy Men

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What is this study about?

This clinical trial is focused on studying the effects of a medication called rifaximin on certain mental and physical responses in healthy men. The study involves healthy volunteers who do not have any intestinal or psychological issues. The main goal is to see if rifaximin, which is taken as a film-coated tablet, can change the gut bacteria in a way that might reduce reactions to stress and fear.

Participants in the study will be randomly assigned to receive either rifaximin or a placebo, which is a tablet that looks like the medication but does not contain the active ingredient. The study will observe how the medication affects various responses, such as stress levels measured by saliva tests, skin reactions, and heart rate. Additionally, the study will look at changes in gut bacteria and other health markers.

The trial is designed to be “triple-blind,” meaning that neither the participants, the researchers, nor the people analyzing the results will know who is receiving the actual medication or the placebo. This helps ensure that the results are unbiased. The study will take place over a period of time, with participants taking the medication or placebo and undergoing various tests to measure their responses to stress and fear.

1 joining the study

Upon joining the study, you will be required to provide voluntary written informed consent. This means you agree to participate after understanding the study details.

You must be proficient in English or Dutch, be a healthy male aged 18-50 years, and have a body mass index (BMI) between 18.5 and 25 kg/m².

2 initial assessment

An initial assessment will be conducted to ensure you meet all the criteria for participation. This includes confirming your health status and ensuring you have no intestinal or psychological complaints.

3 medication administration

You will be randomly assigned to receive either the medication rifaximin or a placebo. The placebo is a tablet that looks like the medication but does not contain the active substance.

The medication or placebo will be taken orally in the form of a film-coated tablet. The dosage is 550 mg, and it will be administered as directed by the study team.

4 monitoring and assessments

Throughout the study, you will undergo various assessments to monitor your responses. These include measuring salivary cortisol levels, which is a hormone related to stress, and completing subjective stress reports.

Other assessments include measuring skin conductance levels, which indicate physiological responses to stress, and expectancy ratings, which assess your anticipation of a potentially dangerous stimulus.

5 additional evaluations

Additional evaluations will be conducted to analyze your gut microbiota profile, heart rate variability, and levels of short-chain fatty acids (SCFA).

Inflammatory markers, such as cytokine levels and C-reactive protein, will also be measured. Brain activity will be assessed using functional magnetic resonance imaging (fMRI) to observe responses to stress.

6 completion of the study

The study is expected to conclude by September 30, 2025. Upon completion, you may be asked to participate in a final assessment to gather any remaining data required for the study.

Who Can Join the Study?

The participant must provide voluntary written informed consent. This means they agree to join the study after being fully informed about it.
The participant must be able to speak and understand English or Dutch.
The participant must be healthy with no complaints related to the intestines or psychological issues.
The participant must have access to a freezer that can reach -18°C, which is a typical household freezer.
Only male participants can join the study.
The participant must be between the ages of 18 and 50 years.
The participant’s Body Mass Index (BMI) must be between 18.5 and 25 kg/m². BMI is a measure of body fat based on height and weight.

Who Cannot Join the Study?

Participants must be healthy volunteers. This means you should not have any current medical conditions.
Only men can participate in this study.
Participants should not be part of a vulnerable population. This means you should not be in a group that needs special protection, like children or people with certain disabilities.

Where you can join this trial?

Verified and Recommended Sites

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Verified Sites

Site Name	City	Country	Status
Katholieke Universiteit te Leuven	Leuven	Belgium

Other Sites

No sites found in this category

Trial status

Country	Status	Recruitment Start
Belgium	Not recruiting	01.10.2022

Trial locations

Investigated drugs:

Rifaximin

Rifaximin is a medication used in this study to see if it can change the bacteria in the gut. The researchers want to find out if these changes can help reduce stress and fear responses in healthy men. Rifaximin works by affecting the gut microbiota, which is the community of microorganisms living in the intestines. By altering these microorganisms, the study aims to see if there is a positive impact on how the body and mind react to stress and fear.

Healthy volunteers – Healthy volunteers are individuals who do not have the disease or condition being studied. They participate in clinical trials to help researchers understand how a disease progresses or how a treatment affects the body. In studies involving healthy volunteers, researchers may focus on understanding normal biological or psychological processes. These individuals provide baseline data that can be compared to data from patients with the disease. Healthy volunteers are crucial for ensuring that new treatments are safe and effective. Their participation helps in identifying potential side effects and understanding the body’s response to new interventions.

Trial ID:

2024-517808-11-00

Protocol code:

S66407

NCT ID:

NCT05587036

Trial Phase:

Therapeutic exploratory (Phase II)

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Study on the Effects of Rifaximin on Stress and Fear Responses in Healthy Men

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