Aniruddha Pratap Singh

Background: Adequate gastric mucosal visibility (GMV) is essential for high quality upper gastrointestinal (GI) endoscopy. Simethicone and N‐acetylcysteine (NAC) are commonly used to improve mucosal visibility, but the optimal timing of administration remains uncertain. Objective: This double‐blinded randomized controlled trial (RCT) evaluated the optimal interval between premedication (simethicone + NAC) and endoscopy for achieving adequate GMV. Design: In this RCT, adults undergoing elective upper GI endoscopy were randomized to four groups: placebo (Group 1), premedication to endoscopy interval of 10–20 (Group 2), 21–30 (Group 3), or > 30 min (Group 4). GMV was scored in four gastric regions (antrum, distal body, proximal body, fundus) on a 4‐point scale (range 4–16). The primary outcome was adequate GMV (total score < 7). Secondary outcomes included median total GMV score, region‐wise mucosal visibility scores, lesion detection rate, and predictors of adequate GMV. Results: A total of 1200 adults were randomized to four groups. Adequate GMV was significantly more frequent in Groups 3 (64.7%) and 4 (66.7%) than in placebo (2.7%) or Group 2 (25.0%). Subgroup analysis within Group 4 demonstrated a declining trend after 50 min. ROC analysis suggested an optimal cut‐off of 25 min in predicting adequate GMV with area under the curve of 0.80. In region‐wise analysis, mean visibility scores were lowest in antrum and distal body. There was no significant difference in the detection of gastric lesions across study groups ( p = 0.913). No serious adverse events related to premedication were observed. Conclusion: Premedication with simethicone and NAC significantly improves GMV. The improvement becomes optimal at 20–30 min after ingestion and is consistently maintained up to 50 min. Trial Registration: ClinicalTrials.gov identifier: NCT06581783