Administration of maximum dose of mucolytic solution before upper endoscopy - a double-blind, randomized trial.

"Conflicts of interest There are no conflicts of interest."

"The authors thank Eva Hruskova Reinova, State Institute for Drug Control, Czech Republic, for her help with application for approval of the study by the State Institute for Drug Control. This work was supported by the Agel Educational and Research Institute (grant number: INT2021005). The funder played no role in the study design, analysis, decision to publish, or preparation of the manuscript. The authors thank Eva Hruskova Reinova, State Institute for Drug Control, Czech Republic, for her help with application for approval of the study by the State Institute for Drug Control. This work was supported by the Agel Educational and Research Institute (grant number: INT2021005). The funder played no role in the study design, analysis, decision to publish, or preparation of the manuscript."

"The study was conducted from May to September 2021, at the Digestive Diseases Center, Vitkovice Hospital, Ostrava, Czech Republic. The endoscopists involved in the study were experienced endoscopists who perform more than 300 gastroscopies per year. The study protocol was approved by the local ethics committee, the State Institute for Drug Control of the Czech Republic, and was registered in the Clinical Studies Registry at ClinicalTrials.gov (NCT04641455). All patients enrolled in the study signed informed consent and a General Data Protection Regulation consent form. Patients who met the inclusion criteria, that is, aged over 18 years, who were able to understand and sign the informed consent, indicated for diagnostic gastroscopy were included in the study. The exclusion criteria included planned therapeutic endoscopy, known organic gastric disease or status post gastric surgery, gastroscopy indicated for bleeding, dysphagia or impaired passage, gastroscopy under general anesthesia, allergy to mucolytic solution components and excipients, and pregnancy. All patients fasted 6 h before gastroscopy."