Background and aims: The results of a phase III, placebo-controlled study demonstrated that endoscopic direct spraying of l-menthol onto the gastric mucosa effectively suppressed gastric peristalsis in the study patients. The aim of the study reported here was to determine whether the anti-peristaltic effect of an l-menthol preparation facilitates endoscopic examinations in a clinical setting. Methods: This was a multicenter, open-label, single-arm trial in which the study cohort comprised patients in whom l-menthol was likely to be used to facilitate endoscopic examination in clinical settings. The primary outcome was the proportion of subjects with no peristalsis (Grade 1) after treatment and at the end of endoscopy (defined as the complete suppression of gastric peristalsis). This variable was assessed according to the level of anti-Helicobacter pylori immunoglobulin G (IgG) antibody, pepsinogen test results, whether sedation was performed, and whether subjects were considered unsuitable for the use of conventional antispasmodics. Results: Of the 119 enrolled subjects, data from 112 were included in the primary efficacy analysis. Gastric peristalsis was completely suppressed in 37.5% of the patients [42/112 patients; 95% confidence interval (CI) 28.5-47.1]. Subgroup analyses revealed that the rate of peristalsis suppression was significantly higher in patients with elevated levels of anti-H. pylori IgG antibody (26/44, 59.1%; 95% CI 43.2-73.7); P < 0.001] and positive pepsinogen test results (21/35, 65.6%; 95% CI 46.8-81.4; P < 0.001]. There was no significant difference according to sedation (17/52, 32.7%; 95% CI 20.3-47.1; P = 0.434) or whether subjects were considered unsuitable for use of conventional antispasmodic agents (14/28, 50.0%; 95% CI 30.6-69.4; P = 0.12]. Conclusion: These findings are comparable to those of the phase III placebo-controlled study and provide further evidence that endoscopic direct spraying of l-menthol effectively suppresses gastric peristalsis during upper gastrointestinal endoscopy.
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