Background/AimsIrsogladine maleate, an enhancer of gastric mucosal protective factors, has demonstrated its efficacy for various gastric mucosal injuries. The aim of this study was to evaluate the efficacy and safety of irsogladine for prevention of nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin-induced peptic ulcer and gastritis.MethodsIn this multicenter, randomized, double-blind, exploratory clinical trial, 100 patients over 50 years of age who needed continuous NSAIDs or aspirin for more than 8 weeks were randomly assigned to either test group (irsogladine maleate 2 mg, twice daily, 39 patients for full analysis) or placebo group (37 patients for full analysis). Primary outcomes were incidence of peptic ulcer and ratio of modified Lanza score (MLS) 2 to 4. Secondary outcome was the number of acute erosions confirmed by endoscopy at 8 weeks. Adverse effects were also compared.ResultsThere were no significant differences in gastric protective effects between test and placebo groups. However, two cases of peptic ulcer in the placebo group but none in the test group were observed. These two cases of peptic ulcer were Helicobacter pylori-negative. In addition, H. pylori-negative group showed significant changes in MLS score (p = 0.0247) and edema score (p = 0.0154) after the treatment compared to those before treatment in the test group. There was no significant difference in adverse events between the two groups.ConclusionsThe efficacy of irsogladine maleate was found in H. pylori-negative group, suggesting its potential as a protective agent against NSAIDs or aspirin-induced peptic ulcer and gastritis.