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NCT Number: NCT07295314

Effect of Antifungals on the Intestinal Microbiome - a Randomized, Controlled, Proof-of-concept Trial

The goal of this clinical trial is to learn how the antifungal drug fluconazole affects the gut microbiome and immune system in healthy volunteers.

The main questions it aims to answer are:

* Does fluconazole change the gut bacteriome and mycobiome composition after 14 days of treatment? * How long do these changes last (4 weeks and 6 months after treatment)? * Does fluconazole affect the body's immune responses, such as blood cell activity and antifungal antibodies?

Researchers will compare two groups: participants who take fluconazole for 14 days and participants who receive no intervention.

Participants will:

* Either take one fluconazole tablet (200 mg) daily for 14 days, or receive no treatment * Provide stool samples and blood samples at several timepoints * Return for follow-up visits up to 6 months after treatment

This study is conducted at Amsterdam UMC, location AMC, with a planned enrollment of 50 healthy male volunteers aged 18-35 years.

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Key information

Conditions

Gut Microbiome Antifungal Therapy Healthy Adult Male

Age range

18 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Early Phase 1

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male, 18-35 years of age at the time of signing informed consent
  • Healthy, as determined by medical history and physical examination; minor clinical abnormalities allowed if not introducing additional risk or interfering with study procedures
  • Capable of giving written informed consent and able to comply with study requirements
  • Normal defecation pattern (≤3 times/day and ≥3 times/week)

Exclusion criteria

  • Major illness in the past 3 months, or significant chronic medical illness deemed unfavorable for enrollment
  • Past or current gastrointestinal disease that may influence the gut microbiota (including inflammatory bowel disease or medication-treated irritable bowel syndrome)
  • History of immunodeficiency
  • History of malignancy
  • Alcohol intake >3 units/day on average
  • Known allergy to antifungal drugs
  • Use of antibiotics (except topical) within the past 3 months
  • Use of antifungals (except topical) within the past 3 months
  • Planned prolonged travel (>4 weeks) to tropical countries during the study period
  • Receipt of an investigational product within 3 months prior to study day 0
  • Use of prescription or non-prescription drugs, herbal or dietary supplements within 3 months (unless deemed safe by investigator)
  • Difficulty with blood donation or poor venous access in either arm
  • Donation of >500 mL of blood in the past 3 months
  • Any other condition or circumstance that, in the investigator's opinion, could be harmful to the subject or compromise data interpretation

Treatment and study plan

Fluconazole 200mg tab

Drug

Oral administration of one 200 mg fluconazole tablet once daily for 14 days.

Primary outcomes

  1. Effect of fluconazole on the intestinal microbiome

    Time frame: 14 days (end of treatment)

    Difference in gut bacteriome and mycobiome composition, ⍺- and ß-diversity between adults treated with an antifungal (fluconazole) and no intervention directly after completion of antifungal treatment (t=14 days).

Secondary outcomes

  1. Gut microbiome and mycobiome composition at 6 months post-treatment

    Time frame: 6 months post-treatment

    Differences in gut bacteriome and mycobiome composition, including α- and β diversity, between fluconazole and no-intervention arms and compared to baseline, 6 months after completion of fluconazole treatment.

  2. Gut microbial functional profiles after fluconazole treatment

    Time frame: Baseline, 14 days, 4 weeks, and 6 months

    Differences in gut microbial functional profiles, including metabolic pathways and in vitro fecal microbial fermentation, between fluconazole and no-intervention arms

  3. Systemic innate immune responses after fluconazole treatment

    Time frame: Baseline, 14 days, 4 weeks, and 6 months

    Differences in host systemic innate immune response profiles between fluconazole and no-intervention arms at baseline, 14 days, 4 weeks, and 6 months. Responses will be assessed using ex vivo stimulation assays of peripheral blood mononuclear cells and neutrophils, and measurement of antifungal antibodies.

Sponsors and collaborators

Lead sponsor

Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)

Other

Collaborators

  • ZonMw: The Netherlands Organisation for Health Research and Development

Registry information

Acronym: FAME

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Dec 19, 2025
Registry last updated
Dec 19, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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