The goal of this randomized, double-blind, single-center clinical trial RELEIF is to learn if medical devices work to decrease symptoms of gastroesophageal reflux disease (GERD) in adults' patients. It will also teach us about safety, tolerability and improvement of patient's quality of life during and after taking medical device. The main questions it aims to answer are:

• Does medical device relieve reflux symptoms?
• Does medical device improve the quality of life of patients with GERD symptoms? Researchers will compare medical device to a placebo (a look-alike substance that contains no drug) to see if medical device works in GERD gastroesophageal reflux disease .

Participants will:

• Take medical device or a placebo every day (4 times a day) for 14 days
• Stop taking medical device or placebo for 7 days (wash out period)
• Switch the therapy for medical device or placebo for next 14 days
• Visit the clinic 4 times during 35 days of this study for checkups and tests
• Keep a diary of their symptoms and the number of times they use a medical device
• Fill out the form to collect all necessary data.

This medical device was developed as a modern therapeutic alternative, offering rapid symptom relief and long-term protective effects on the esophageal mucosa. The introduction of medical device aims to expand the available therapeutic options for patients suffering from GERD symptoms and to support physicians in selecting optimal therapy. Thanks to its innovative formula, medical device can avoid the rising the symptoms, provide improved well-being and reduce the frequency of acute medication use.

Inclusion Criteria:

• Diagnosis of gastroesophageal reflux disease based on the presence of typical symptoms such as heartburn and or regurgitation for at least 6 months prior to the screening visit, confirmed by the investigator
• Exclusion of erosive reflux disease, Barrett esophagus, and other esophageal abnormalities by upper gastrointestinal endoscopy within the last 6 months, confirmed by the investigator based on medical documentation
• No use within 1 month prior to screening of proton pump inhibitors, H2 receptor antagonists, prokinetics such as itopride or prucalopride, GLP1 or GIP analogues, antibiotics, baclofen, tricyclic antidepressants, serotonin and or noradrenaline reuptake inhibitors, and no use within 1 week prior to screening of sucralfate, antacids, or esophageal mucosal protective agents
• Presence of gastroesophageal reflux symptoms that negatively impact quality of life, as subjectively reported by the patient and confirmed by the investigator
• Age 18 years or older at the time of screening
• Women of childbearing potential must not be pregnant confirmed by a negative urine pregnancy test and must not be breastfeeding, or must be of non childbearing potential defined as surgically sterile, physiologically incapable of becoming pregnant, or at least 12 months post menopause
• Women of childbearing potential with a male partner of reproductive potential must use a highly effective method of contraception from screening until 18 weeks after the last dose of the investigational medical device
• Sexually active men with women of childbearing potential must agree to use barrier contraception such as condoms or abstain from sexual intercourse throughout the study period and for at least 7 days after the last dose of the investigational medical device
• Ability to comply with all aspects of the clinical study
• Male patients eligible for participation in the study.

Exclusion Criteria:

• Women who are breastfeeding or have a positive urine pregnancy test at the baseline visit
• Introduction of significant changes in diet or lifestyle during the study period
• Presence of alarm symptoms at baseline including dysphagia or odynophagia, unintentional weight loss greater than 5 percent of baseline body weight, signs of gastrointestinal bleeding, anemia, palpable epigastric mass, or persistent vomiting lasting 7 to 10 days
• Planned use during the study of antibiotics, probiotics, prebiotics, synbiotics, short chain fatty acids, proton pump inhibitors, H2 receptor antagonists, prokinetics such as itopride or prucalopride, GLP1 or GIP analogues, baclofen, tricyclic antidepressants, serotonin and or noradrenaline reuptake inhibitors, and use within 1 week prior to study start of sucralfate, antacids, or esophageal mucosal protective agents
• Diagnosis of a severe disease such as malignancy
• Planned hospitalization for any reason or presence of any severe comorbidity that in the opinion of the investigator constitutes a contraindication to study participation or may compromise patient safety
• Current or recent history within 1 year prior to randomization of alcohol dependence or substance abuse
• Active psychiatric disorders that in the opinion of the investigator may interfere with compliance with study procedures
• Presence of unstable or uncontrolled cardiovascular disorders, moderate or severe heart failure classified as New York Heart Association class III or IV, or any clinically significant pulmonary, hepatic, renal, gastrointestinal, genitourinary, hematological, coagulation, immunological, endocrine or metabolic disorder, or any other medical condition that in the opinion of the investigator could affect study results or patient safety
• Individuals who are employees of the study site, investigator, contract research organization, or sponsor
• First degree relatives of employees of the study site, investigator, contract research organization, or sponsor
• Individuals unable to attend all study visits or comply with study procedures.

Individual participant data will not be made publicly available due to privacy considerations and applicable data protection regulations. Aggregated and anonymized results will be reported in scientific publications. Data may be available from the corresponding author upon reasonable request, subject to institutional approval and data sharing agreements.

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