An open-label, single-arm study assessing the efficacy and safety of L: -menthol sprayed onto the gastric mucosa during upper gastrointestinal endoscopy

Menthol: An underestimated anticancer agent

Menthol, a widely used natural, active compound, has recently been shown to have anticancer activity. Moreover, it has been found to have a promising future in the treatment of various solid tumors. Therefore, using literature from PubMed, EMBASE, Web of Science, Ovid, ScienceDirect, and China National Knowledge Infrastructure databases, the present study reviewed the anticancer activity of menthol and the underlying mechanism. Menthol has a good safety profile and exerts its anticancer activity via multiple pathways and targets. As a result, it has gained popularity for significantly inhibiting different types of cancer cells by various mechanisms such as induction of apoptosis, cell cycle arrest, disruption of tubulin polymerization, and inhibition of tumor angiogenesis. Owing to the excellent anticancer activity menthol has demonstrated, further research is warranted for developing it as a novel anticancer agent. However, there are limitations and gaps in the current research on menthol, and its antitumor mechanism has not been completely elucidated. It is expected that more basic experimental and clinical studies focusing on menthol and its derivatives will eventually help in its clinical application as a novel anticancer agent.

Antiperistaltic effect and safety of L-menthol for esophagogastroduodenoscopy in the elderly with contraindication to hyoscine-N-butylbromide

Hyoscine-N-butylbromide (HBB) is the most used antiperistaltic agent during esophagogastroduodenoscopy (EGD). However, almost half of the elderly have a contraindication to HBB. We aimed to evaluate l-menthol’s antiperistaltic effect and safety for EGD in the elderly with contraindication to HBB. This prospective, randomized, double-blind, placebo-controlled study screened 86 elderly patients (≥ 65 years old) scheduled to undergo EGD, and 52 of them with contraindication to HBB were enrolled. The participants were randomized to receive l-menthol (n = 26) or a placebo (n = 26), which was locally sprayed on the gastric antrum endoscopically. The proportion of patients with no or mild peristalsis after medication and at the end of EGD was significantly higher in the l-menthol group (76.9%) than in the placebo group (11.5%, p < 0.001). l-Menthol administration significantly reduced peristaltic grade, improved contraction parameters, and eased intragastric examination relative to the placebo (p < 0.001, respectively). Hemodynamic changes, adverse events, and discomfort levels of patients were similar between the two groups. l-Menthol is an effective and safe alternative antiperistaltic medication for EGD in elderly patients with contraindication to HBB. Further large, randomized trials are required to clarify whether l-menthol can lead to better detection yield in the elderly.

Clinical trial registration: The study was registered at ClinicalTrials.gov (NCT04593836).

L-Menthol for Gastrointestinal Endoscopy: A Systematic Review and Meta-Analysis

In randomized controlled trials, L-menthol inhibits gastrointestinal peristalsis during endoscopy. Our goal was to quantitatively synthesize the available evidence to evaluate the efficacy and safety of L-menthol for gastrointestinal endoscopy.

Effect of spraying l-menthol on peristalsis resumption during endoscopic submucosal dissection of gastric tumors

Background and Aim

l‐Menthol has smooth muscle‐relaxing and antiperistaltic effects. We examined its effectiveness against peristalsis resumption during endoscopic submucosal dissection (ESD) of gastric tumors.

Methods

We retrospectively examined clinical data of 485 patients (501 lesions) who underwent ESD for upper gastrointestinal tumors in 2017. We included 119 patients (127 lesions) in whom peristaltic movement resumed during ESD and l‐menthol was applied; 366 patients (374 lesions) without l‐menthol application were used as controls. Video recordings were reviewed to determine whether l‐menthol suppressed peristalsis resumption.

Results

In cases with l‐menthol application, 2 (2.9%), 36 (14.3%), and 89 (71.2%) lesions were found in the upper (U), middle (M), and lower (L) regions, respectively. In the control group, the corresponding values were 66 (17.6%), 215 (57.5%), and 93 (24.9%), respectively. l‐Menthol efficacy was observed in 116 of the 127 treated lesions (91.3%), over 90% of which were in the posterior wall of the U region, anterior wall and greater curvature of the M region, and anterior wall and lesser curvature of the L region. The most and least effective areas for l‐menthol application were the anterior wall of gastric antrum and posterior wall of the M region, respectively. The mean time from application to peristalsis inhibition was 8.7 s. No adverse effects were observed; perforation and secondary hemorrhage were not significantly different between the groups.

Conclusion

Direct l‐menthol application to the submucosal layer during mucosal resection affects smooth muscles and rapidly inhibits peristalsis resumption. Clinically, l‐Menthol can be used to suppress peristalsis recurrence during ESD, without adverse effects.

Peppermint Oil to Improve Visualization in Screening Colonoscopy: A Randomized Controlled Clinical Trial

Background

Screening colonoscopy has been associated with reduced mortality from colorectal cancer by means of early detection and timely treatment. However, visualization during colonoscopy is often impaired since the colon is naturally prone to peristalsis and spasm. There is evidence to suggest benefit of topical peppermint oil in causing smooth muscle relaxation, thereby decreasing peristalsis. The aim of our study was to determine if peppermint oil helps reduce colonic spasticity so as to allow for better visualization during screening colonoscopy.

Methods

We performed a randomized controlled, double-blinded, clinical trial where patients undergoing screening colonoscopy were assigned to receive either peppermint oil or placebo. Once cecum was reached, 50 mL of either solution was directly injected via the working channel of the colonoscope. Colonic peristalsis, spasticity and bowel visibility were documented. Bowel preparation quality, withdrawal time and adenoma detection rate (ADR) were also assessed. Continuous variables were analyzed using t-test or Wilcoxon rank-sum test while categorical variables were compared using the two-way Chi-square test.

Results

Forty-eight patients were included, of whom 24 patients received peppermint oil and 24 received placebo. Mean Boston bowel preparation score (BBPS) was excellent for both groups (8 points vs. 7.9 points; P = 0.98). Both mean total colonoscopy time (17.8 min vs. 21.9 min; P = 0.07) and mean cecal intubation time (7.2 min vs. 10.3 min; P = 0.04) were shorter with peppermint oil as compared to placebo. Complete absence of bowel spasticity was observed among 58.3% patients in the peppermint oil group as compared to 45.8% patients in the placebo group (P = 0.05). More than 75% of bowel was visualized in 83% of patients in both groups (P = 0.56). Mean ADR was higher in the peppermint group as compared to the placebo group (45.8% vs. 37.5%; P = 0.56).

Conclusion

Our study suggests that topical peppermint oil reduces bowel wall spasticity, which could lead to better visualization of the bowel during screening colonoscopy. Although use of peppermint oil was associated with better ADRs, these results did not achieve statistical significance. Larger sample size and use of alternative methods of peppermint oil administration allowing for more absorption time may establish stronger results.

CLINICAL APPLICATION OF L-MENTHOL IN THE UPPER GASTROINTESTINAL ENDOSCOPIC PROCEDURE

AIM

Peppermint oil, which suppresses gastric peristalsis during esophagogastroduodenoscopy (EGD), is effective for determining the margin of a gastric tumor. This study was conducted to evaluate the utility of an L-menthol preparation for suppressing gastric peristalsis and for diagnosing gastric tumors.

METHODS

The study examined 124 patients who underwent EGD between January and April 2012. After 20 mL of 0.8% L-menthol was sprayed directly onto the mucosal surface of the gastric antrum, the degree of peristalsis suppression in the antrum was evaluated. The effectiveness of L-menthol for identifying new gastric tumors and determining tumor margins was also evaluated.

RESULTS

Gastric peristalsis was suppressed in 88.5% (69/78) of patients, with complete suppression of peristalsis achieved in 78.2%. L-menthol exerted a higher peristalsis-suppressive effect in patients with endoscopic gastric mucosal atrophy (93.3%, 56/60) than in patients without atrophy (72.2%, 13/18) (p = .014). L-menthol application caused the detection of new gastric tumors in 1.6% (2/124) of patients and clarification of the margin of three lesions (in 3 patients) identified as having an unclear margin before L-menthol application.

CONCLUSION

These results suggest that L-menthol is effective for suppressing gastric peristalsis during EGD and suggest that it is useful for identifying gastric tumors and for determining tumor margins.

l-Menthol sprayed on gastric mucosa causes edematous change

BACKGROUND AND STUDY AIMS

l-Menthol (LM), sprayed on the distal gastric mucosa, is a safe antispasmodic agent used during esophagogastroduodenoscopy (EGD). However, it seems to affect gastric mucosal endoscopic findings. Therefore, we evaluated whether LM causes specific changes and impacts the endoscopic morphology of gastric lesions.

PATIENTS AND METHODS

A total of 98 patients scheduled to undergo EGD were randomly assigned to receive LM solution (160 mg of 0.8 % LM added to 2.5 mL of indigo carmine [IC]; n = 49; LM group) or decuple-diluted IC solution without LM (n = 49; placebo group). We compared the incidence of specific mucosal changes and the difference in the endoscopic findings of several gastric lesions between these groups.

RESULTS

Annular-reticular - like mucosal changes appeared immediately after the administration of LM solution. This change was observed in 71.4 % of the LM group compared with 12.2 % of the placebo group (P < 0.01). In the placebo group, this change was observed in 14.7 % of subjects with atrophic gastritis compared with 6.7 % of those without atrophic gastritis (P = 0.39), whereas in the LM group, this change was observed in 84.8 % of subjects with atrophic gastritis compared with 43.8 % of those without atrophic gastritis (P < 0.01). Most early gastric cancers, erosions, and ulcers observed in this study became well demarcated after LM administration, although the incidence of gastric lesions did not differ significantly between the two groups.

CONCLUSION

LM changes the gastric mucosa into edematous mucosa, and this occurs more frequently in atrophic gastric mucosa than in pathologic lesions. LM may facilitate the demarcation of pathologic gastric lesions without intestinal metaplasia.

Efficacy of spraying l-menthol solution during endoscopic treatment of early gastric cancer: a phase III, multicenter, randomized, double-blind, placebo-controlled study

BACKGROUND

The topical antispasmodic agent l-menthol is useful for inhibiting gastric peristalsis during diagnostic upper gastrointestinal endoscopy. However, it remains unclear whether l-menthol is similarly effective during therapeutic endoscopy, thereby improving treatment outcomes in a clinical setting.

METHODS

A total of 83 patients scheduled to undergo endoscopic treatment at 8 Japanese referral centers were randomly assigned to receive l-menthol or placebo. The degree of gastric peristalsis (peristaltic score: grade 1-5) was assessed by an independent committee. The primary outcome was the proportion of subjects in whom no or mild peristalsis (grade 1 or 2) was maintained throughout endoscopic treatment. Secondary outcomes were the duration of sustained response and the incidence of adverse drug reactions.

RESULTS

The proportion of patients with no or mild peristalsis was significantly higher in the l-menthol group (85.4 %, 95 % confidence intervals 70.8-94.4: 35/41 subjects) than in the placebo group (39.0 %, 24.2-55: 16/41; P < 0.001). The sustained response rates in the l-menthol and the placebo were, respectively, 90.0 and 39.6 % 30 min post-dose, and 79.9 and 35.7 % at the completion of the resection. The sustained response rates were significantly higher in the l-menthol group than in the placebo group (P < 0.001, log-rank test). The incidence of adverse drug reactions did not differ significantly between the two groups (P = 1.000).

CONCLUSIONS

During gastric endoscopic submucosal dissection, spraying l-menthol on the gastric mucosa significantly suppressed peristalsis, with minimal adverse drug reactions as compared with placebo. l-menthol solution might be useful for therapeutic endoscopy.