title: Premedication with pronase or N-acetylcysteine improves visibility during gastroendoscopy: an endoscopist-blinded, prospective, randomized study.
abstract: OBJECTIVE
  To assess the efficacy of premedicaton with pronase or N-acetylcysteine (NAC) at 20 min before upper gastrointestinal (UGI) endoscopy and to determine whether pronase or NAC pretreatment influences the reliability of the rapid urease test.
  
  
  METHODS
  A total of 146 patients were prospectively and randomly assigned into the study groups according to different premedications before endoscopy. One endoscopist assessed mucosal visibility (MV) with scores ranged from 1 to 4 at four sites in the stomach. The sum of the MV scores from these four locations was defined as the total mucosal visibility (TMV) score. Identification of H pylori was performed using CLO test, histology, and serology.
  
  
  RESULTS
  The Group with pronase premedication had a significantly lower TMV score than did the groups with gascon and gascon water (P < 0.001 and P < 0.01, respectively). The group with NAC had a significantly lower TMV score than the group with gascon (P < 0.01) and a trend of a lower MV score than the group with gascon water (P = 0.06). The TMV score did not significantly differ between the group with pronase and the group with NAC (P = 0.39 and P = 0.14, respectively). The sensitivity and specificity of the CLO test were 92.5% and 93.9%, respectively, in groups premedicated with pronase and NAC together.
  
  
  CONCLUSIONS
  Premedication with pronase or NAC at 20 min before UGI endoscopy improves the mucosal visibility of the stomach. Neither pronase nor NAC produces any obvious interference with the CLO test for the identification of H pylori infection.
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Taipei Medical University Hospital, 252 Wu-Hsing Street, Taipei 110, Taiwan, China. chunchao@tmu.edu.tw
authors.forename: Chun-Chao
authors.initials: CC
authors.lastname: Chang
authors.forename: Sheng-Hsuan
authors.initials: SH
authors.lastname: Chen
authors.forename: Chih-Ping
authors.initials: CP
authors.lastname: Lin
authors.forename: Ching-Ruey
authors.initials: CR
authors.lastname: Hsieh
authors.forename: Horng-Yuan
authors.initials: HY
authors.lastname: Lou
authors.forename: Fat-Moon
authors.initials: FM
authors.lastname: Suk
authors.forename: Shiann
authors.initials: S
authors.lastname: Pan
authors.forename: Ming-Shun
authors.initials: MS
authors.lastname: Wu
authors.forename: Jun-Nan
authors.initials: JN
authors.lastname: Chen
authors.forename: Yung-Fa
authors.initials: YF
authors.lastname: Chen
mesh_terms: D000111:Acetylcysteine; D000328:Adult; D000368:Aged; D004129:Dimethylpolysiloxanes; D005100:Expectorants; D005260:Female; D005773:Gastroscopy / Q000379:methods*; D016481:Helicobacter Infections / Q000175:diagnosis; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008875:Middle Aged; D011292:Premedication; D011402:Pronase; D011446:Prospective Studies; D016037:Single-Blind Method; D014510:Urease
chemical_list: D004129:Dimethylpolysiloxanes; D005100:Expectorants; D011402:Pronase; D014510:Urease; D000111:Acetylcysteine