Esophagogastroduodensocopy (EGD) Procedure

The goal of this randomized, double-blind, placebo-controlled clinical trial is to assess whether the combination of N-acetylcysteine and simethicone improves mucosal visibility during upper gastrointestinal endoscopy in adults aged 18 to 99 years of both sexes, including both healthy individuals and those with non-bleeding gastrointestinal symptoms. The main questions this study aims to answer are: Does pre-endoscopy administration of N-acetylcysteine/simethicone improve mucosal visualization based on the Toronto Upper Gastrointestinal Cleanliness Score (TUGS)? Is this combination safe and well tolerated in this patient population? Researchers will compare patients receiving N-acetylcysteine (600 mg) and simethicone (100 mg) orally 20-60 minutes before the procedure with those receiving placebo (water) to determine if there is a significant improvement in TUGS scores. Participants will: Receive a single oral dose of either N-acetylcysteine/simethicone or placebo prior to endoscopy Undergo a routine upper GI endoscopy Have mucosal cleanliness evaluated using the TUGS scoring system Be monitored for any adverse events or intolerance

The goal of this clinical trial is to learn if administering ondansetron prior to esophagogastroduodenoscopy (EGD) can alleviate the gagging reflex, nausea and vomiting in Chinese patients undergoing unsedated diagnostic EGD. The main questions it aims to answer are: Does taking ondansetron prior to EGD reduce the discomfort of patients during the endoscopic process? Does taking ondansetron prior to EGD reduce the intensity of patient gagging and nausea, and the incidence of vomiting ? Researchers will compare premedication of oral ondasetron and topical pharyngeal anesthesia (dyclonine hydrochloride mucilage) with topical pharyngeal anesthesia only to see if ondansetron can exert the above-mentioned effects. Participants will be treated with one of the following regimens according to the randomization result: * Oral ondansetron of 8 mg 2 hours prior to endoscopic process and dyclonine hydrochloride mucilage to be gurgled 15 minutes prior to endoscopic process; * dyclonine hydrochloride mucilage to be gurgled 15 minutes prior to endoscopic process. After the endoscopic process is finished, patients will be asked to fill in a questionnaire that contains the following items, all measured by NRS 0-10: * Overall discomfort; * Intensity of gagging; * Willingness to undergo unsedated EGD again if indicated.