Premedication With N-acetylcysteine and Simethicone to Improve Mucosal Visualization in Elective Upper Endoscopy (NACSIMET)

November 20, 2025 updated by: Hospital General de Mexicali

Randomized Controlled Trial to Evaluate the Effect of Premedication With N-acetylcysteine and Simethicone on Mucosal Visibility During Elective Upper Gastrointestinal Endoscopy Using the TUGS Score

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

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a randomized, double-blind, placebo-controlled, multicenter clinical trial designed to evaluate the efficacy of N-acetylcysteine (NAC) combined with simethicone in improving mucosal visibility during upper gastrointestinal endoscopy (UGIE). The evaluation will be based on the Toronto Upper Gastrointestinal Cleanliness Score (TUGS), a validated tool to assess mucosal cleanliness.

Participants will include adult patients aged 18 to 99 years who are scheduled to undergo diagnostic UGIE for various indications and who do not present with active gastrointestinal bleeding. Eligible participants will be randomized to receive either a single dose of NAC (600 mg) plus simethicone (100 mg) or a placebo (water), administered orally 20 to 60 minutes prior to the procedure. The allocation will be blinded to both participants and endoscopists.

The main objective of the study is to determine whether this premedication protocol results in better mucosal visibility, as measured by the total TUGS score. Secondary objectives include documenting the presence of significant endoscopic findings and histopathological diagnoses, and evaluating the tolerability and safety profile of the premedication.

TUGS scores will be assigned by trained endoscopists blinded to the treatment allocation. Variables such as age, sex, BMI, duration of fasting, hospital site, and endoscope model will be recorded and controlled for in statistical analyses. The study will also assess any potential adverse events associated with the administration of NAC/simethicone.

This study is categorized as Phase 2 because it evaluates the preliminary efficacy and short-term safety of pre-procedural oral N-acetylcysteine (NAC) and simethicone to improve mucosal visibility during diagnostic upper gastrointestinal endoscopy, using the Toronto Upper Gastrointestinal Cleaning Score (TUGCS) as a validated surrogate endpoint. Both agents have established safety profiles for other indications, but their combined use for this indication is not an approved or established standard of care. The trial is randomized, double-blind, placebo-controlled with a moderate sample size designed to estimate effect size and variability rather than to deliver definitive, multi-center confirmatory evidence on hard clinical outcomes.

All procedures will adhere to ethical standards, and informed consent will be obtained from all participants. Data will be collected in a coded, anonymized format and analyzed using appropriate statistical methods, including ANCOVA and non-parametric tests where assumptions of normality are not met.

Study Type

Interventional

Enrollment (Estimated)

132

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Mexico
    • Estado de Baja California
      • Mexicali, Estado de Baja California, Mexico, 21000
        • Recruiting
        • Hospital Almater
        • Contact:
      • Mexicali, Estado de Baja California, Mexico, 21100
        • Recruiting
        • Hospital General de Mexicali
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Men and women aged 18 to 70 years old.
  • Patients who agree to participate in the clinical trial.
  • Patients without active gastrointestinal bleeding.
  • Signing of informed consent form.

Exclusion Criteria:

  • Patients with a history of hypersensitivity to N-acetylcysteine
  • Patients with a history of hypersensitivity to simethicone
  • Patients with a previous endoscopic diagnosis
  • Patients with a history of gastric or bariatric surgery
  • Patients with a history of motor disorders (e.g., scleroderma, diabetic gastroparesis)
  • Patients taking medications that delay gastric emptying (GLP-1 analogues)
  • Pregnant or breastfeeding patients
  • Patients who do not agree to participate in the clinical trial

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Patients receiving n-acetylcysteine/simethicone
Drug: Premedication with n-acetylcysteine
Once the sample size has been calculated, patients who meet the inclusion criteria will be recruited. who will be randomized using the "Randomized for Clinical Trial" program for assignment to treatment groups A and B. Group A will receive 600 mg of N-acetylcysteine and 100 mg of simethicone orally 20 to 60 minutes before the procedure, while the control group will receive an equivalent placebo infusion (composed of drinking water). Premedication and placebo will be labeled in containers as medication or placebo by external personnel not involved in the study, and the identification of each bag will be noted on a sheet and kept in an envelope that will be opened at the end of the study. Tolerance will be evaluated. If any adverse events are identified, the principal investigator will be notified for action regarding the management of the adverse event and its reporting.
Drug: Premedication with simethicone
Once the sample size has been calculated, patients who meet the inclusion criteria will be recruited. who will be randomized using the "Randomized for Clinical Trial" program for assignment to treatment groups A and B. Group A will receive 600 mg of N-acetylcysteine and 100 mg of simethicone orally 20 to 60 minutes before the procedure, while the control group will receive an equivalent placebo infusion (composed of drinking water). Premedication and placebo will be labeled in containers as medication or placebo by external personnel not involved in the study, and the identification of each bag will be noted on a sheet and kept in an envelope that will be opened at the end of the study. Tolerance will be evaluated. If any adverse events are identified, the principal investigator will be notified for action regarding the management of the adverse event and its reporting
Placebo Comparator: Patients receiving placebo
Drug: Placebo (drinking water)
The control group will receive an equivalent placebo infusion (composed of drinking water)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Total score on the Toronto Upper Gastrointestinal Cleaning Score (TUGCS)
Time Frame: During the index upper endoscopy (Day 0), scored intra-procedure (≈20-60 minutes after premedication).
The Toronto Upper Gastrointestinal Cleaning Score (TUGCS) is a validated scale that assesses mucosal cleanliness/visualization across four upper GI areas (fundus, body, antrum, and duodenum). Each area is scored from 0 to 3 (0 = poorest visualization; 3 = entire mucosa visible without suctioning/washing). The total score is the sum of all four areas (range 0-12). Higher scores indicate better mucosal cleanliness/visibility. Scoring is performed by blinded assessors during the procedure using standardized criteria.
During the index upper endoscopy (Day 0), scored intra-procedure (≈20-60 minutes after premedication).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Detection of Mucosal Lesions
Time Frame: During endoscopy procedure
Number of patients in whom mucosal lesions are detected during the procedure.
During endoscopy procedure
Complete Esophageal Visualization
Time Frame: During endoscopy.
Binary assessment (Yes/No) of whether complete esophageal visualization was achieved.
During endoscopy.
Histological gastritis according to the Updated Sydney System (0-3 per item) and OLGA/OLGIM staging (0-IV)
Time Frame: Biopsies obtained during the index endoscopy (Day 0); histopathological report within 14 days

Measurement tool: Updated Sydney System (sum of domains not mandatory).

Sites and technique: 5 gastric biopsies according to the Sydney protocol (2 antrum, 2 body, 1 incisura angularis), fixed in formalin; H&E and Giemsa staining (or IHC if necessary for H. pylori).

Domains and ranges (each 0-3):

H. pylori density: 0 = absent, 1 = mild, 2 = moderate, 3 = marked.

Chronic inflammation (mononuclear): 0-3.

Activity (neutrophils): 0-3.

Glandular atrophy: 0-3.

Intestinal metaplasia: 0-3. Minimum-maximum range per domain: 0-3; higher scores = worse histological severity.

Risk staging:

OLGA (0-IV) for atrophy, OLGIM (0-IV) for intestinal metaplasia; higher stages = worse stage/higher risk.

Reported measure: distribution of scores per domain (0-3) and proportion per OLGA/OLGIM stage (0-IV), comparing arms.
Biopsies obtained during the index endoscopy (Day 0); histopathological report within 14 days
Presence and density of Helicobacter pylori by histology (Updated Sydney System 0-3)
Time Frame: Biopsies obtained during the index endoscopy (Day 0); report within 14 days

Measurement tool: Updated Sydney System for H. pylori.

Range and direction: 0-3 (0 = not detected; 1 = mild; 2 = moderate; 3 = marked). Higher scores = higher bacterial density.

Technique: H&E + Giemsa staining (or IHC if indeterminate).

Reported measure:

Proportion of patients positive for H. pylori (≥1 on the scale), and

Distribution of categories 0-3 per arm.
Biopsies obtained during the index endoscopy (Day 0); report within 14 days
Number of histologically confirmed neoplasic lesions per patient
Time Frame: During the index endoscopy (Day 0) and histological confirmation up to 14 days
Higher values reflect higher detection performance; this should be interpreted in conjunction with the detection rate (NDR)
During the index endoscopy (Day 0) and histological confirmation up to 14 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hospital General de Mexicali

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 12, 2025

Primary Completion (Estimated)

November 30, 2026

Study Completion (Estimated)

December 31, 2026

Study Registration Dates

First Submitted

September 10, 2025

First Submitted That Met QC Criteria

November 20, 2025

First Posted (Actual)

November 24, 2025

Study Record Updates

Last Update Posted (Actual)

November 24, 2025

Last Update Submitted That Met QC Criteria

November 20, 2025

Last Verified

September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • NACSIMET-ETDA-MEX2025

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data related to baseline demographics, Toronto Upper Gastrointestinal Cleaning Score (TUGS), endoscopic findings, and histopathological results.

IPD Sharing Time Frame

IPD will be available beginning 6 months after publication of the main results and for up to 3 years thereafter.

IPD Sharing Access Criteria

Researchers whose proposed use of the data has been approved by the study's principal investigator.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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