Metronidazole, Bismuth Oxide and Tetracycline Hydrochloride Fixed‑Dose Combination vs Standard First‑line Therapy for Adults with Helicobacter pylori Infection

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What is this study about?

The trial enrolls adults who have Helicobacter pylori infection, a bacterial condition that can lead to stomach ulcers and discomfort. The purpose is to determine whether a new fixed‑dose combination treatment is not worse than the standard first‑line therapy for eliminating the infection.

The new test medication combines three ingredients: Metronidazole, Bismuth oxide and Tetracycline hydrochloride. The standard regimen used for comparison contains a proton‑pump inhibitor (Esomeprazole) together with two antibiotics, Clarithromycin and Amoxicillin, plus metronidazole.

Participants take the assigned pills for about two weeks, after which they undergo a breath test called the Urea Breath Test that checks for the presence of the bacteria. Follow‑up visits record any side effects, how well the medication was taken, and whether the infection has been cleared.

1 randomization and medication pack receipt

after joining the study, the patient is assigned by the study system to one of two treatment groups. the assignment is concealed from the patient (single‑blind).

the patient receives a sealed medication pack that contains all tablets needed for the treatment period. the pack includes written instructions that describe how and when each tablet should be taken.

2 baseline urea breath test

on the first day, the patient provides a breath sample for a urea breath test (ubt). this test uses a small amount of a harmless substance called 13c‑urea to confirm the presence of helicobacter pylori infection before treatment begins.

3 start of eradication therapy (days 1–14)

the patient begins the medication regimen immediately after the baseline ubt. the regimen depends on the assigned group:

test arm (fixed‑dose combination): take four tablets of the combination containing metronidazole, bismuth oxide and tetracycline hydrochloride twice daily (morning and evening) with water. the total duration is 14 days.

comparator arm (standard quadruple therapy): take the following tablets twice daily for 14 days:

– esomeprazole 40 mg capsule (two capsules per day, total 80 mg) to reduce stomach acid,

– clarithromycin 500 mg film‑coated tablet,

– amoxicillin 1 g dispersible tablet,

– metronidazole 500 mg hard capsule.

all tablets in the comparator arm are taken with meals unless otherwise indicated in the written instructions.

4 daily medication diary and adherence monitoring

throughout the 14‑day treatment period, the patient records each dose taken in a provided diary. the diary is used later to assess whether at least 90 % of the prescribed units were consumed.

the patient returns any unused tablets to the study site at the end of the treatment period for count verification.

5 post‑treatment follow‑up urea breath test (approximately day 28)

two weeks after completing the medication course, the patient returns for a second urea breath test. this test determines whether the helicobacter pylori infection has been cleared.

the result of this test is the primary measure of treatment success in the study.

6 final study visit and completion

during the final visit, the patient discusses any adverse events experienced during the trial, returns the completed diary, and receives a summary of study participation.

no further medication is required after the follow‑up ubt.

Who Can Join the Study?

You must be at least 18 years old.
You must have an active Helicobacter pylori (H. pylori) infection that was confirmed by a gastroscopy (a camera that looks inside the stomach) and a laboratory CLO test (a test that detects the bacteria).
You must not have received any previous treatment or medication for H. pylori infection.
You must have a clear medical reason to undergo eradication therapy (treatment aimed at removing the infection).
You must be willing and able to take the study medication exactly as prescribed, at the correct dose and schedule, for the entire study period.
You must agree to sign a voluntary written informed consent form before any study procedures begin.

Who Cannot Join the Study?

Taking any antibiotics (drugs that kill bacteria) within the last 4 weeks.
Taking proton‑pump inhibitors (PPIs) or potassium‑competitive acid blockers (PCABs) (medicines that lower stomach acid) within the last 2 weeks.
Taking bismuth compounds (a type of medicine sometimes used for stomach problems) within the last 4 weeks.
Having Zollinger‑Ellison syndrome, a rare condition that makes the stomach produce too much acid.
Having serious problems with major organs, such as severe or unstable heart, lung, or hormone diseases.
Having any of the following stomach or digestive problems: bleeding in the gastrointestinal tract, iron‑deficiency anemia (low iron causing tiredness), Barrett’s esophagus (changes in the lining of the esophagus) or high‑grade dysplasia (severe abnormal cells), difficulty swallowing (dysphagia), or idiopathic thrombocytopenic purpura (ITP) (low platelet count that can cause bleeding).
Having Cockayne syndrome, a rare genetic disorder that affects growth and development.
Having low potassium (hypokalaemia) or low magnesium (hypomagnesaemia) because these can lengthen the heart’s QT interval and increase the risk of abnormal heart rhythms.
Having diagnosed or suspected atrophic gastritis (thinning of the stomach lining) that could interfere with the urea breath test used to detect Helicobacter pylori.
Any other medical condition or laboratory result during screening that the doctor believes is important enough to prevent participation.
History of substance or alcohol abuse within the past year.
Allergy (hypersensitivity) to any of the study drugs (metronidazole, bismuth, tetracycline, amoxicillin, clarithromycin, esomeprazole, 13C‑urea) or to related drug classes, or a severe immediate allergic reaction (such as anaphylaxis) to beta‑lactam antibiotics (e.g., penicillins, cephalosporins).
History of a prolonged QT interval (congenital or acquired) or dangerous heart rhythm problems, including a type called torsades de pointes.
Being pregnant or breastfeeding (lactation).
Regular use of non‑steroidal anti‑inflammatory drugs (NSAIDs) or systemic steroids (anti‑inflammatory medicines) within the past 4 weeks.
Use of blood thinners (anticoagulants) or antiplatelet agents (medicines that prevent clotting) within the past 4 weeks, except low‑dose aspirin (100 mg per day or less).
Taking any other prohibited medication that could have serious interactions with the study treatments.
Having had previous stomach or upper gastrointestinal surgery, such as gastric surgery or gastrectomy.
Having severe additional illnesses, such as advanced kidney, liver, or heart failure, or having cancer (malignancy).

Where you can join this trial?

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Other Sites

Site Name	City	Country
Evangelismos S.A.	Athens	Greece
401 General Military Hospital Of Athens	Athens	Greece
General University Hospital Of Larissa	Larissa	Greece
Ippokratio General Hospital Of Thessaloniki	Thessaloniki	Greece
Henry Dunant Hospital Center	Athens	Greece
Tzaneion General Hospital	Athens	Greece
Attikon University Hospital	Athens	Greece
Ippokrateio General Hospital of Athens	Athens	Greece
Alexandra General Hospital	Athens	Greece
Nea Ionia General Hospital – “Konstantopouleio – Patision”	Athens	Greece
General Hospital of Nikaia–Piraeus “Agios Panteleimon”	Athens	Greece
University Hospital of Ioannina	Athens	Greece
Lngya Gbwvizt Hmbuvbgq Oq Awuhwa	Athens	Greece
Acndne Mpsxhde Csnpls Stpm	Thessaloniki	Greece

Trial status

Country	Status	Recruitment Start
Greece	Not yet recruiting	30.06.2026

Trial locations

Investigated drugs:

Esomeprazole is a medication that reduces the amount of acid made by the stomach. In this study it is given to help protect the stomach lining and create a better environment for the antibiotics to work against the infection.

Clarithromycin is an antibiotic that kills bacteria. It is part of the standard treatment regimen used in the trial to try to clear the Helicobacter pylori infection.

Amoxicillin is another antibiotic that works by stopping bacteria from building their cell walls. It is combined with other medicines in the standard therapy to increase the chance of eradicating the infection.

Metronidazole is an antibiotic that is effective against certain types of bacteria and other microorganisms. In the trial it is used as part of the standard four‑drug regimen and also appears in the experimental combination.

Metronidazole, Bismuth oxide, and Tetracycline combination is the test product being evaluated. It combines three agents in one tablet: metronidazole (an antibiotic), bismuth oxide (a compound that coats the stomach lining and has mild antibacterial effects), and tetracycline (an antibiotic that stops bacterial growth). The study tests whether this fixed‑dose combination works as well as the standard therapy for removing Helicobacter pylori.

13C‑urea breath test is a diagnostic tool used to detect Helicobacter pylori infection. Patients swallow a small amount of a special substance (13C‑urea), and the breath is analyzed to see if the bacteria are present. This test helps confirm that participants have the infection before treatment begins.

Helicobacter pylori infection – Helicobacter pylori infection is a bacterial infection of the stomach lining caused by the spiral‑shaped bacterium Helicobacter pylori. The bacteria settle in the protective mucus of the stomach, leading to irritation and inflammation. As the infection persists, the stomach lining can become thicker and develop small sores. Continued inflammation may cause changes in the lining that result in ulcer formation.

Trial ID:

2026-525291-26-00

Protocol code:

HELICA/VER

Trial Phase:

Therapeutic confirmatory (Phase III)

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Metronidazole, Bismuth Oxide and Tetracycline Hydrochloride Fixed‑Dose Combination vs Standard First‑line Therapy for Adults with Helicobacter pylori Infection

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?