Obesity & OverweightPhase 4NCT07850960
Effect of Omeprazole on Gut Microbiota in Adults With Obesity and GERD
A Phase 4 study testing Omeprazole and Standard Non-pharmacological Recommendations for GERD in people with Obesity & Overweight and Gastroesophageal Reflux Disease, run by Federal State Budgetary Scientific Institution at 1 site in Russia.
Trial summary
This randomized, open-label, parallel-group study will evaluate the effect of short-term omeprazole therapy on gut and oral microbiota in adults aged 50-65 years with obesity and symptomatic gastroesophageal reflux disease. Read more about this study
- Who is it for?
- Ages 50 to 65 years
- Conditions the study is for
- Obesity & Overweight, Gastroesophageal Reflux Disease
- What is being tested?
- Omeprazole and Standard Non-pharmacological Recommendations for GERD
- Type of treatment
- Pill or oral medicine, Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 26 participants
- Where
- 1 siteRussia
- Study dates
- 25 Sep 2026to 25 Dec 2026
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 50 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 50 to 65 years, inclusive.
- Obesity, defined as body mass index (BMI) ≥30 kg/m².
- Symptomatic gastroesophageal reflux disease with mild or moderate typical symptoms, including heartburn and/or regurgitation.
- For female participants, postmenopausal status, defined as absence of menstruation for at least 12 months without another apparent cause of amenorrhea.
- Written informed consent to participate in the study.
Who cannot join
- Severe or exacerbated GERD, or GERD requiring acid-suppressive therapy or additional diagnostic evaluation.
- Use of proton pump inhibitors or histamine H2-receptor antagonists within 8 weeks prior to enrollment.
- Use of systemic antibiotics within 3 months prior to enrollment.
- Use of probiotic or synbiotic supplements within 8 weeks prior to enrollment.
- Inflammatory bowel disease, celiac disease, or other severe chronic gastrointestinal disorders that may substantially affect the gut microbiota.
- History of bariatric surgery or other major gastrointestinal surgery.
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- Acute infectious or inflammatory disease at enrollment.
- History of myocardial infarction or stroke.
- Type 2 diabetes mellitus.
- Chronic heart failure, New York Heart Association functional class III-IV.
- Chronic kidney disease with estimated glomerular filtration rate <30 mL/min/1.73 m².
- Alcohol dependence or other substance use disorder.
- Severe psychiatric disorder or cognitive impairment that may interfere with providing informed consent or adherence to the study protocol.
- Known hypersensitivity or contraindications to omeprazole.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Russia1 site
Federal Research Centre of Nutrition, Biotechnology and Food Safety
Moscow, 115446
Georgy Leonov, MD, PhD, +7 9055687783, golerus@gmail.com
About this study
Official title: Effect of Proton Pump Inhibitors on Gut Microbiota Composition in Adults With Obesity and Gastroesophageal Reflux Disease
This randomized, open-label, parallel-group study will evaluate the effect of short-term omeprazole therapy on gut and oral microbiota in adults aged 50-65 years with obesity and symptomatic gastroesophageal reflux disease. Participants will be randomized 1:1 to receive omeprazole 20 mg once daily for 14 days plus standard non-pharmacological recommendations for gastroesophageal reflux disease, or standard non-pharmacological recommendations alone. Clinical and laboratory assessments will be performed at baseline and after 14 days. Stool and saliva samples will be collected to assess gut and oral microbiota, and blood samples will be collected for laboratory biomarkers.
- Being tested
- Omeprazole, Standard Non-pharmacological Recommendations for GERD
- Keywords
- Gut Microbiota, Oral Microbiota, Omeprazole, Proton Pump Inhibitors, GERD, 16S rRNA Sequencing
- Medical subject headings
- Obesity, Overweight, Gastroesophageal Reflux
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
OmeprazoleDrug
Omeprazole 20 mg administered orally once daily for 14 days.
Standard Non-pharmacological Recommendations for GERDBehavioural
Standard non-pharmacological recommendations for gastroesophageal reflux disease management.
| Study group | Role | What they receive |
|---|---|---|
| Omeprazole Plus Standard Non-pharmacological Recommendations | Experimental | Participants will receive omeprazole 20 mg orally once daily for 14 days in addition to standard non-pharmacological recommendations for gastroesophageal reflux disease. Receives: Drug: Omeprazole; Behavioral: Standard Non-pharmacological Recommendations for GERD |
| Standard Non-pharmacological Recommendations | Active comparator | Participants will receive standard non-pharmacological recommendations for gastroesophageal reflux disease for 14 days. Receives: Behavioral: Standard Non-pharmacological Recommendations for GERD |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in gut microbiota beta diversity
Gut microbiota beta diversity will be assessed using distance-based measures derived from 16S rRNA gene sequencing of stool samples, including Bray-Curtis dissimilarity and phylogenetic UniFrac distances.
Measured: Baseline and Day 14
Secondary outcomes (6)
Change in Shannon diversity index
Change in gut microbiota alpha diversity assessed using the Shannon diversity index derived from 16S rRNA gene sequencing of stool samples. Higher values indicate greater microbial diversity.
Measured: Baseline and Day 14
Change in Simpson diversity index
Change in gut microbiota alpha diversity assessed using the Simpson diversity index derived from 16S rRNA gene sequencing of stool samples. Values range from 0 to 1, with higher values indicating greater microbial diversity.
Measured: Baseline and Day 14
Change in Chao1 richness estimator
Change in gut microbiota richness assessed using the Chao1 richness estimator derived from 16S rRNA gene sequencing of stool samples. Higher values indicate greater estimated microbial richness.
Measured: Baseline and Day 14
Change in modified Frequency Scale for the Symptoms of GERD total score
Change in the total modified Frequency Scale for the Symptoms of GERD (mFSSG) score from baseline to Day 14. The questionnaire includes 14 items scored from 0 to 4. The total score ranges from 0 to 56, with higher scores indicating more frequent GERD-related symptoms.
Measured: Baseline and Day 14
Change in high-sensitivity C-reactive protein concentration
Change in serum high-sensitivity C-reactive protein (hs-CRP) concentration.
Measured: Baseline and Day 14
Change in systemic immune-inflammation index
Change in the systemic immune-inflammation index (SII), calculated as platelet count × neutrophil count / lymphocyte count.
Measured: Baseline and Day 14
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Oct 2026
- Study start25 Sep 2026 (estimated)
- Primary completion25 Dec 2026 (estimated)
- Study completion25 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity & OverweightStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 26 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Federal State Budgetary Scientific Institution
- Sponsor type
- Other government
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07850960
- Sponsor's protocol ID
- PPI-MICROBIOME-7-02-09-2026
- Other IDs
- 22-15-00252-P
- Status last verified
- Sep 2026
- First submitted
- 24 Sep 2026
- Last updated
- 1 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 1 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Proton Pump Inhibitors on Gut Microbiota Composition in Adults With Obesity and Gastroesophageal Reflux Disease
- ClinicalTrials.gov ID
- NCT07850960
- Acronym / sponsor ID
- PPI-MICROBIOME-7-02-09-2026
- Keywords
- Gut Microbiota, Oral Microbiota, Omeprazole, Proton Pump Inhibitors, GERD, 16S rRNA Sequencing
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 26 participants (estimated)
- Lead sponsor
- Federal State Budgetary Scientific InstitutionOther government
- Study start
- 25 Sep 2026 (estimated)
- Primary completion
- 25 Dec 2026 (estimated)
- Study completion
- 25 Dec 2026 (estimated)
- First posted
- 1 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This randomized, open-label, parallel-group study will evaluate the effect of short-term omeprazole therapy on gut and oral microbiota in adults aged 50-65 years with obesity and symptomatic gastroesophageal reflux disease. Participants will be randomized 1:1 to receive omeprazole 20 mg once daily for 14 days plus standard non-pharmacological recommendations for gastroesophageal reflux disease, or standard non-pharmacological recommendations alone. Clinical and laboratory assessments will be performed at baseline and after 14 days. Stool and saliva samples will be collected to assess gut and oral microbiota, and blood samples will be collected for laboratory biomarkers.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Omeprazole Plus Standard Non-pharmacological Recommendations | Experimental | Drug: Omeprazole, Behavioral: Standard Non-pharmacological Recommendations for GERDParticipants will receive omeprazole 20 mg orally once daily for 14 days in addition to standard non-pharmacological recommendations for gastroesophageal reflux disease. |
| Standard Non-pharmacological Recommendations | Active comparator | Behavioral: Standard Non-pharmacological Recommendations for GERDParticipants will receive standard non-pharmacological recommendations for gastroesophageal reflux disease for 14 days. |
Who may qualify
- Ages
- 50 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Age 50 to 65 years, inclusive.
- Obesity, defined as body mass index (BMI) ≥30 kg/m².
- Symptomatic gastroesophageal reflux disease with mild or moderate typical symptoms, including heartburn and/or regurgitation.
- For female participants, postmenopausal status, defined as absence of menstruation for at least 12 months without another apparent cause of amenorrhea.
- Written informed consent to participate in the study.
Key exclusion criteria (14 listed)
- Severe or exacerbated GERD, or GERD requiring acid-suppressive therapy or additional diagnostic evaluation.
- Use of proton pump inhibitors or histamine H2-receptor antagonists within 8 weeks prior to enrollment.
- Use of systemic antibiotics within 3 months prior to enrollment.
- Use of probiotic or synbiotic supplements within 8 weeks prior to enrollment.
- Inflammatory bowel disease, celiac disease, or other severe chronic gastrointestinal disorders that may substantially affect the gut microbiota.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| OmeprazoleOmeprazole 20 mg administered orally once daily for 14 days. | Drug | Omeprazole Plus Standard Non-pharmacological Recommendations |
| Standard Non-pharmacological Recommendations for GERDStandard non-pharmacological recommendations for gastroesophageal reflux disease management. | Behavioural | Omeprazole Plus Standard Non-pharmacological Recommendations, Standard Non-pharmacological Recommendations |
Primary outcome
Change in gut microbiota beta diversity
Time frame: Baseline and Day 14
Gut microbiota beta diversity will be assessed using distance-based measures derived from 16S rRNA gene sequencing of stool samples, including Bray-Curtis dissimilarity and phylogenetic UniFrac distances.
6 secondary outcomes
Change in Shannon diversity index
Time frame: Baseline and Day 14
Change in Simpson diversity index
Time frame: Baseline and Day 14
Change in Chao1 richness estimator
Time frame: Baseline and Day 14
Change in modified Frequency Scale for the Symptoms of GERD total score
Time frame: Baseline and Day 14
Change in high-sensitivity C-reactive protein concentration
Time frame: Baseline and Day 14
Change in systemic immune-inflammation index
Time frame: Baseline and Day 14
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Oct 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Omeprazole and Standard Non-pharmacological Recommendations for GERD in people with Obesity & Overweight and Gastroesophageal Reflux Disease, run by Federal State Budgetary Scientific Institution at 1 site in Russia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 1 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Russia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Georgy E. Leonov, MD, PhD (+7 9055687783, golerus@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in gut microbiota beta diversity (time frame: Baseline and Day 14). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Oct 2026.