Peppermint oil reduces gastric spasm during upper endoscopy: a randomized, double-blind, double-dummy controlled trial

Background: GI endoscopy without general anesthesia causes a hyperperistaltic state in the stomach, which frequently necessitates the use of antispasmodic agents, such as hyoscine-N-butylbromide, but these drugs have side effects. Peppermint oil is harmless and acts locally to inhibit GI smooth muscle contraction. Methods: A randomized double-blind, double-dummy, controlled trial was conducted in 100 patients to compare the antispasmodic effects of hyoscine-N-butylbromide administered intra-muscularly and a placebo solution administered intraluminally by means of the endoscope, and also the effects of a placebo solution administered intramuscularly with those of a peppermint oil solution administered intraluminally. The percent change in diameter of the pyloric ring before and after the administrations was defined as the opening ratio, and the percent change in diameter between the maximally and minimally opened pyloric ring states was defined as the contraction ratio. Time until disappearance of the contraction ring(s) in the gastric antrum and side effects of the drugs were also determined. Results: The opening ratio was significantly higher in the peppermint oil administration group than in the hyoscine-N-butylbromide injection group. The contraction ratio after peppermint oil administration was significantly lower than that after hyoscine-N-butylbromide injection. The time required for disappearance of the antral contraction ring(s) was shorter in the peppermint oil group (97.1 +/- 11.4) than in the hyoscine-N-butylbromide group (185.9 +/- 10.1 s; p < 0.0001). No significant side effects were associated with peppermint oil, whereas hyoscine-N-butylbromide injection produced side effects such as dry mouth, blurred vision, and urinary retention. Conclusions: Peppermint oil solution administered intraluminally can be used as an antispasmodic agent with superior efficacy and fewer side effects than hyoscine-N-butylbromide administered by intramuscular injection during upper endoscopy.