Premedication with N-acetylcysteine and simethicone improves mucosal visualization during gastroscopy: a randomized, controlled, endoscopist-blinded study

Eur J Gastroenterol Hepatol. 2013 Jul;25(7):778-83. doi: 10.1097/MEG.0b013e32836076b2.


Objectives: Diagnostic gastroscopy provides a unique opportunity to diagnose early oesophagogastric neoplasia; however, intraluminal mucus and bile can obscure mucosal visualization. The aim of this study was to determine whether the use of a premedication solution containing the mucolytic agent N-acetylcysteine and the surfactant simethicone improves mucosal visualization within a UK diagnostic gastroscopy service.

Materials and methods: A total of 75 consecutive patients were recruited from a single (S.J.) endoscopist's diagnostic gastroscopy list. They were randomized into three treatment groups: (a) standard control=clear fluids only for 6 h, nil by mouth for 2 h; (b) water control=standard control+100 ml sterile water (given 20 min before gastroscopy); and (c) solution=standard control+100 ml investigated solution (20 min before gastroscopy). The endoscopist was blinded to patient preparation. Inadequate mucosal visualization was defined as fluid/mucus during gastroscopy that could not be suctioned and required flushing with water. The volume of flush, the site at which it was used and the total procedure times were recorded.

Results: All three groups showed no statistical difference for age, sex ratio, procedure priority or indication. The mean volume of flush required to obtain clear mucosa was significantly less in the solution group compared with the other groups. The mean overall procedure time was also less in the solution group compared with the other groups.

Discussion: Premedication with N-acetylcysteine and simethicone markedly improves mucosal visibility during gastroscopy. It also reduces the time taken for the procedure. This low-cost and well-tolerated intervention may improve detection of early neoplasia.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Acetylcysteine / administration & dosage*
  • Acetylcysteine / adverse effects
  • Adult
  • Aged
  • Chi-Square Distribution
  • Duodenum / metabolism
  • Duodenum / pathology*
  • Endoscopy, Digestive System*
  • England
  • Esophagogastric Junction / metabolism
  • Esophagogastric Junction / pathology*
  • Expectorants / administration & dosage*
  • Expectorants / adverse effects
  • Female
  • Gastric Mucosa / metabolism
  • Gastric Mucosa / pathology*
  • Humans
  • Intestinal Mucosa / metabolism
  • Intestinal Mucosa / pathology*
  • Male
  • Middle Aged
  • Mucus / metabolism
  • Predictive Value of Tests
  • Premedication* / adverse effects
  • Simethicone / administration & dosage*
  • Simethicone / adverse effects
  • Surface-Active Agents / administration & dosage*
  • Surface-Active Agents / adverse effects
  • Therapeutic Irrigation
  • Time Factors
  • Young Adult


  • Expectorants
  • Surface-Active Agents
  • Simethicone
  • Acetylcysteine