Background: GI peristalsis during GI endoscopy commonly requires intravenous or intramuscular injection of antispasmodic agents, which sometimes cause unexpected adverse reactions. Objective: Our ultimate goal was to evaluate whether the antiperistaltic effect of L-menthol-based preparations facilitates endoscopic examinations in a clinical setting. Design: Multicenter, randomized, double-blind, placebo-controlled study. Setting: Six Japanese referral centers. Patients and Intervention: A total of 87 patients scheduled to undergo upper GI endoscopy were randomly assigned to receive 160 mg of L-menthol (n = 45) or placebo (n = 42). Both treatments were sprayed endoscopically on the gastric mucosa. The degree of gastric peristalsis was assessed by an independent committee. Main Outcome Measurements: The proportion of subjects with no peristalsis 90 to 135 seconds after administration and at the end of the endoscopic examination (complete suppression of gastric peristalsis). Other outcomes were the proportion of subjects with no or mild peristalsis (adequate suppression of gastric peristalsis) and the ease of intragastric observation as evaluated by the endoscopist who performed the procedure. Results: Gastric peristalsis was completely suppressed in 35.6% (21.9, 51.2) of the L-menthol group compared with only 7.1% (1.5, 19.5) of the placebo group (P < .001). In the L-menthol group, 77.8% (62.9, 88.8) (35/45 subjects) of the subjects had no or mild peristalsis at the completion of endoscopy. Minor peristalsis interfered with intragastric examination in only 1 of these 35 patients (2.9%). The incidence of adverse events did not differ significantly between the groups (P = .512). Limitation: Small sample size. Conclusions: During upper GI endoscopy, L-menthol sprayed on the gastric mucosa significantly suppresses peristalsis with minimal adverse drug reactions compared with placebo.
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