Pre-medication With N-acetylcysteine and Simethicone to Improve Mucosal Visibility During Gastroduodenoscopy

AIM: In this study, we aimed to evaluate the impact of premedication with simethicone or N-acetylcysteine (NAC) for mucosal visualisation during esophagogastroduodenoscopy (EGD).

This is a single-centre, double blinded (patients and endoscopist), randomized trial at a tertiary care academic hospital and approved by institutional review board committee (AIG/IEC-BFI and R 29 /06.2022-04).

The eligibility criteria for enrollment into the study include adult patients (>18 y) undergoing esophagogastroduodenoscopy (EGD). Exclusion criteria for the study are history of upper gastrointestinal surgery, neurological disorder with impaired swallowing, active gastrointestinal bleeding, caustic ingestion, pregnancy, known history of multiple allergies, gastric outlet obstruction, esophageal motility disorders, and contraindication for EGD.

Randomization Patients will be randomly assigned to one of four categories. The randomization algorithm is generated using Random Allocation Software v2.0. Before EGD, a clinical research coordinator will deliver the sealed randomization envelopes to a trained nurse who will administer the solution to the patients after obtaining written informed consent from the study participants. In this trial, both patients and endoscopists will be unaware of the allocation.

Interventions Patients will be randomized to the following 4 groups: group A [100 mL of water (W)]; group B [150 mg simethicone (S)]; group C [600 mg NAC (NAC)]; and group D [150 mg simethicone +600 mg NAC (SPN)]. Patients, nursing staff assisting the procedure, the endoscopist performing the procedure, and the research coordinator collecting the data will be blinded. Identical bottles will be used in all the groups for the purpose of blinding.

A trained nurse not participating in the study will administer the solution 10-30 minutes before EGD. All patients will receive pharyngeal anesthesia with 4 squirts of 10% lidocaine (Xylocaine spray 10%; Neon, Thane, India) before EGD.

After EGD, all patients will be observed for two hours for any immediate adverse events. As feasible, delayed adverse events will be evaluated within 24 hours via telephone inquiry or in-person visits.

Mucosal visibility scoring A pre-defined scoring system will be used for grading mucosal visibility in four regions in stomach (fundus, proximal body, distal body and antrum) and two regions in duodenum [first (D1 and second (D2)]. The mucosal visibility scores range from 1 to 4 (1, no adherent mucus; 2, mild mucus, but not obscuring vision; 3, large amount of mucus obscuring vision, with less than 50 ml water required to clear it; 4, heavy adherent mucus, requiring more than 50 ml water to clear). Total mucosal visibility scores (TMVS) will be estimated by adding individual mucosal visibility scores in six different regions in stomach and duodenum. The TMVS ranges from 6 (best) to 24 (worst) points.

Outcome measures The primary outcome of the study is comparison of TMVS between combined pre-medication (SPN) and individual pre-medication groups (S and NAC) in patients undergoing EGD. Secondary outcomes include comparison of TMVS between different groups (A vs B vs C vs D), TMVS in early (10-20 min) versus late (>20-30 min) endoscopy groups, adequate gastric mucosal visibility, detection of lesions and adverse events related to the pre-medications. Adequate and inadequate gastric mucosal visibility is defined as a cumulative score of <7 and ≥7, respectively.

Sample size calculation In this study we aim to assess the impact of pre-medication on mucosal visibility (MVS) during EGD. We postulated that adequate MV will be at least 15% better in the combined pre-medication (WPSN) arm versus simethicone (WPS) arm.4 The sample size calculated was 346 (173 per group) to demonstrate the superiority of pre-medication with type 1 error as 0.05 and 80% power. Since, the study had four arms the estimated sample size was 692. Considering a 15% drop out rate during the follow-up, the number of cases to be enrolled was calculated to be 796 (199 in each group).

Inclusion criteria

• Adults (≥18-years) capable of giving written, informed consent will be included.
• All eligible subjects undergoing diagnostic endoscopy will be recruited in the study.

Exclusion criteria

• History of upperGI tract surgery,
• Gastric cancer
• Need for therapeutic endoscopy and emergency procedures,
• Recent upper GI bleeding
• Caustic ingestion,
• Pregnancy
• Diabetes mellitus
• Asthma
• Allergic reactions to the medications used in the study