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CompletedNCT03273296Updated Aug 19, 2025

Effect of Antibiotics on Gut Microbiome and Plasma Metabolome

A Phase 4 interventional study of Amoxicillin and Azithromycin in Microbial Colonization, sponsored by Finnish Institute for Health and Welfare. Completed at 1 site in Finland. Open to participants aged 40 Years to 74 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-08-19.

Sponsored by Finnish Institute for Health and Welfare · Phase 4, Interventional, and Basic science

Phase
Phase 4
Study type
Interventional
Enrollment
39
Allocation
Randomized
Ages
40 Years to 74 Years
Sex
All
01

Study summary

In recent years it has been observed that the gut microbiome can produce metabolites into systemic circulation and thus have important health effects even outside the gastrointestinal system. These metabolites may play a role in the pathogenesis of common public health problems such as diabetes, obesity and cardiovascular disorders. Modern techniques of mass spectrometry-based metabolomics from peripheral blood and gut metagenome sequencing now enable detailed examination of these processes. Using samples from the FINRISK 2002 cohort, collected by the National Institute for Health and Welfare, we are currently determining the gut microbiome and plasma metabolome from > 7000 participants with 15 years of follow-up for various health outcomes. This is one of the largest materials of its kind world-wide. The design does not, however, allow us to draw causal conclusions on the roles of gut bacteria in the composition of plasma metabolome. To enable conclusions which go beyond statistical associations, we now propose an extension to the FINRISK 2002 study, where we alter the gut bacteriome with a short course of antibiotics and then examine whether a change in plasma metabolomics profile will follow. At the same time the trial will give important novel information about the effects of commonly used antibiotics on gut bacteriome and on general health.

02

Conditions studied

  • Microbial Colonization

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Keywords

  • microbiota
  • metabolize
03

In context

Communicable Diseases

626 studies on the registry are indexed under Communicable Diseases; 128 are open to participants now.

This study's enrollment of 39 is below the median of 89 across 380 interventional studies indexed under Communicable Diseases.

Browse Communicable Diseases studies →

Lead sponsor

Finnish Institute for Health and Welfare is the lead sponsor of 42 studies on the registry; 3 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
40 Years to 74 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Prior participation in the FINRISK 2002 survey and current residence in Helsinki metropolitan area.
  • Age range 40-74 years among men and 50-74 years among women.

Exclusion criteria

Exclusion Criteria:

  • Known allergy to any antibiotic
  • A course of antibiotic during the past year
  • Acute infection
  • Any major illness (history of myocardial infarction, stroke, diabetes, liver or kidney disease, cancer, psychiatric disease). Uncomplicated hypertension is allowed. Likewise, statin treatment and women's hormone replacement therapy are allowed.
05

Study design

Phase
Phase 4
Primary purpose
Basic science
Allocation
Randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
39 participants (actual)

Study arms

  • Active comparator
    Amoxicillin

    Drug: Amoxicillin

  • Active comparator
    Azithromycin

    Drug: Azithromycin

  • Active comparator
    Vancomycin

    Drug: Vancomycin

Interventions

  • Amoxicillin (po) 500 mg x 3 per day for 3 days.

  • Azithromycin (po) 500 mg x 1 on day 1, 250 mg x 1 on day 2, and 250 mg x 1 on day 3.

  • Vancomycin (po) 125 mg x 4 per day for 3 days.

06

What researchers measure

Primary outcomes

  1. Microbiome

    Change in gut microbiome from baseline to repeat assessments.

    Time frame: Baseline: 0 days; repeat assessments 2 days and 28 days after end of antibiotics.

  2. Metabolome

    Change in circulating metabolome from baseline to repeat assessments.

    Time frame: Baseline: 0 days; repeat assessments 2 days and 28 days after end of antibiotics.

07

Study locations

1 site
  • Finnish Institute for Health and Welfare
    Helsinki, 00271, Finland
08

References and documents

Individual participant data

Plan to share: Yes

No publications or documents are linked to this record.

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Ran from Oct 2017 to primary completion in Dec 2017, 2 months.

Of 13 phase 4 interventional studies under Communicable Diseases, half reached primary completion within 38 months of starting (the median), counting those still running; a quarter within 17 and three quarters within 65. This study's 2 months is below that.

How these figures are worked out, and which studies are left out of them.

Registered
Sep 4, 2017
First posted
Sep 6, 2017
StartActual
Oct 15, 2017
Primary completionActual
Dec 15, 2017
CompletionActual
Dec 15, 2017
Last update
Aug 19, 2025
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Aug 19, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03273296
Lead sponsor
Finnish Institute for Health and Welfare
Responsible party
Sponsor
First posted
Sep 6, 2017
Start date
Oct 15, 2017
Primary completion
Dec 15, 2017
Completion
Dec 15, 2017
Last update
Aug 19, 2025

Study contacts

Aki Havulinna, MD, PhD
principal investigator · Finnish Institute for Health and Welfare
Markus Perola, DSc (tech.)
principal investigator · Finnish Institute for Health and Welfare

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Aug 2025. You cannot join it, but the record below documents what was studied.

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Discussion

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Studies of the drugs tested here: Amoxicillin · Azithromycin · Vancomycin

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