A Phase 4 interventional study of Rifaximin in ACS - Acute Coronary Syndrome, Ticagrelor and Microbiota, sponsored by Collegium Medicum w Bydgoszczy. Not yet recruiting at 1 site in Poland. Open to participants aged 18 Years to 80 Years. Per ClinicalTrials.gov, last updated 2025-10-02.
Sponsored by Collegium Medicum w Bydgoszczy · Phase 4, Interventional, and Treatment
The FLORA-ACS study aims to evaluate the relationship between dysbiosis and high platelet reactivity during treatment with ticagrelor in patients with a history of acute coronary syndromes and investigate the use of rifaximin to eliminate dysbiosis and thus provide effective antiplatelet treatment.
A research hypothesis has been formulated indicating dysbiosis of the gut microbiota as a possible cause of high platelet reactivity (HPR) during treatment with an antiplatelet agent, ticagrelor, in post-acute coronary syndrome (ACS) patients. The use of rifaximin, an antibiotic exhibiting an eubiotic effect, may correct gut dysbiosis and help determine whether changes in the microbiota influence HPR.
The FLORA-ACS study will enroll 50 subjects with a history of ACS treated with ticagrelor (standard maintenance dose of 90 mg orally twice a day) and characterized by HPR. Participants will be enrolled in the study no sooner than 1 month and no later than 12 months following the ACS incident.
Platelet activity will be tested using the multiple electrode aggregometry method (Multiplate analyzer) with the HPR defined based on the consensus paper of the Working Group on On-Treatment Platelet Reactivity. Concurrently, fecal samples will be collected for microbiome profiling. The microbiota will be analyzed in terms of fecal bacterial richness and diversity using 16S ribosomal RNA sequencing.
Participants will receive a 7-day course of oral rifaximin (400 mg every 12 hours). Both platelet activity and microbiota testing will be conducted at baseline and post-treatment. Additional laboratory testing will include complete blood count and C-reactive protein. An analysis of major adverse cardiovascular events (MACE) occurrence within a 6-month follow-up period is planned.
1,488 studies on the registry are indexed under Acute Coronary Syndrome; 273 are open to participants now.
This study's planned enrollment of 50 is below the median of 200 across 865 interventional studies indexed under Acute Coronary Syndrome.
Browse Acute Coronary Syndrome studies →Collegium Medicum w Bydgoszczy is the lead sponsor of 26 studies on the registry; 4 are open to participants now.
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Exclusion criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants identified as having high platelet reactivity treated with oral rifaximine
Drug: Rifaximin
Participants receiving a 7-day course of oral rifaximin 400 mg every 12 hours
Also known as: Xifaxan
Change in platelet reactivity in Multiplate
Relative reduction in platelet reactivity from baseline to post-intervention by \>10%, assessed with Multiplate analyzer (multiple electrode aggregometry)
Time frame: 0-7 days
Achievement of platelet reactivity below HPR
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with Multiplate analyzer (multiple electrode aggregometry)
Time frame: 0-7 days
Relative reduction in platelet reactivity
Relative reduction in platelet reactivity from baseline to post-intervention by \>10%, assessed with VerifyNow P2Y12 assay
Time frame: 0-7 days
Achieving platelet reactivity below HPR in VerifyNow
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with VerifyNow P2Y12 assay
Time frame: 0-7 days
Relative reduction in platelet reactivity in thromboelastography
Relative reduction in platelet reactivity from baseline to post-intervention by \>10%, assessed with Platelet Mapping assay (thromboelastography)
Time frame: 0-7 days
Achieving platelet reactivity below HPR in thromboelastography
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with Platelet Mapping assay (thrombelastography)
Time frame: 0-7 days
Changes in microbiome profile
Changes in microbiome profile post-intervention assessed using 16S rRNA sequencing
Time frame: 0-7 days
Plan to share: No
No publications or documents are linked to this record.
Start is estimated for Jan 2026; primary completion for Dec 2026, 11 months later.
Of 85 non-industry phase 4 interventional studies under Acute Coronary Syndrome, half reached primary completion within 45 months of starting (the median), counting those still running; a quarter within 27 and three quarters within 67. This study's planned 11 months is below that.
Counting every sponsor, half of 92 studies reached it within 42 months; a quarter within 26 and three quarters within 60.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Sep 2025. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Rifaximin
Collegium Medicum w Bydgoszczy