Effect of Intraluminal Administration of Menthol Solution During Colonoscopy on Colonic Spasm and Adenoma Detection Rate

Effect of Intraluminal Administration of Menthol Solution During Colonoscopy on Colonic Spasm and Adenoma Detection Rate: An Efficacy and Safety Study

In recent years, with increasing research into antispasmodic agents, topical antispasmodics have attracted considerable attention due to their direct action on the gastrointestinal mucosa and relatively low incidence of adverse reactions. Menthol, a natural terpenoid compound found in peppermint oil, has been confirmed by numerous studies to possess spasmolytic properties. Existing evidence indicates that menthol relaxes intestinal smooth muscle and alleviates spasm symptoms by antagonizing L-type calcium channels on the smooth muscle cell membrane, thereby reducing calcium influx. Furthermore, it exhibits local analgesic effects and can attenuate visceral hypersensitivity. Some studies suggest that oral or topical administration of peppermint oil preparations may improve intestinal spasm during colonoscopy, highlighting its potential utility in digestive endoscopy procedures. Nevertheless, current research on the spasmolytic efficacy and safety of menthol solution when administered via endoscopic irrigation during colonoscopy remains limited, and high-quality clinical trials are urgently needed for validation. This study aims to investigate the effectiveness and safety of menthol solution in relieving intestinal spasm, thereby providing scientific evidence for optimizing colonoscopy procedures.

Study Overview

• Status: Not yet recruiting
• Conditions: Colonoscopy
• Intervention / Treatment: Drug: Endoscopic irrigation was performed using a 0.1% menthol solution combined with simethicone.; Drug: Endoscopic irrigation was performed using an aqueous suspension prepared with simethicone and normal saline.

• Study Type: Interventional
• Enrollment (Estimated): 440
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jianning Yao; Phone Number: 13733183434; Email: rjyy@zzu.edu.cn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Age between 18 and 75 years, regardless of gender;
2. Scheduled to undergo colonoscopy (for screening, diagnostic, or follow-up purposes);
3. Adequate bowel preparation quality (Boston Bowel Preparation Scale score ≥ 6);
4. Voluntarily signed informed consent and able to cooperate with completing study-related assessments.

Exclusion Criteria:

1. Allergy to menthol, cyclodextrin, or related substances;
2. History of severe intestinal diseases (such as ulcerative colitis, Crohn's disease, intestinal perforation, intestinal obstruction, intestinal tumors, etc.);
3. Presence of severe dysfunction of vital organs such as the heart, liver, kidneys, or lungs, or coagulation disorders;
4. Pregnant or lactating women;
5. Use of anticholinergic drugs, calcium channel blockers, or other spasmolytic agents within one week prior to the examination;
6. Psychiatric disorders or cognitive impairment that prevent cooperation with the study;
7. History of contraindications to colonoscopy or serious adverse reactions during previous procedures.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Menthol group; Endoscopic irrigation was performed using a 0.1% menthol solution combined with simethicone. Preparation method: Normal saline was used as the solvent. Menthol cyclodextrin inclusion complex (containing 7.3% menthol) was accurately weighed at 6.85 g and dissolved in 500 ml of normal saline to prepare a 0.1% menthol solution. After complete dissolution, 5 g of simethicone was added to form an aqueous suspension.	Drug: Endoscopic irrigation was performed using a 0.1% menthol solution combined with simethicone.; Preparation method: Normal saline was used as the solvent. Menthol cyclodextrin inclusion complex (containing 7.3% menthol) was accurately weighed at 6.85 g and dissolved in 500 ml of normal saline to prepare a 0.1% menthol solution. After complete dissolution, 5 g of simethicone was added to form an aqueous suspension.
Placebo Comparator: placebo group; Endoscopic irrigation was performed using an aqueous suspension prepared with simethicone and normal saline. Preparation method: 5 g of simethicone was added to 500 ml of normal saline to form the aqueous suspension.	Drug: Endoscopic irrigation was performed using an aqueous suspension prepared with simethicone and normal saline.; Preparation method: 5 g of simethicone was added to 500 ml of normal saline to form the aqueous suspension.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of intestinal spasm	Intestinal spasm score: Score 1 (Excellent): No spasm; the lumen opening is greater than or equal to two-thirds of the maximum diameter. Score 2 (Moderate): Moderate spasm; the lumen opening is less than two-thirds of the maximum diameter. Score 3 (Poor): Severe spasm; the oral-side lumen cannot be visualized. The maximum diameter is defined as the diameter of the intestinal lumen when fully distended. Spasm incidence: The percentage of patients with an intestinal spasm score of 2 or 3 out of the total number of patients in the group.	Day 0
adenoma detection rate (ADR)	ADR = (Number of patients with at least one adenomatous polyp detected / Total number of patients in the group) × 100%. Pathological diagnosis was used as the gold standard.	Day 0

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Spasm inhibition rate	The percentage of patients whose lumen opening exceeded two-thirds of the maximum diameter within 30 seconds after water injection irrigation, relative to the total number of patients in the group.	Day 0
Polyp detection rate (PDR)	PDR = (Number of patients with at least one polyp detected / Total number of patients in the group) × 100%.	Day 0

Collaborators and Investigators

• Sponsor: The First Affiliated Hospital of Zhengzhou University

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: March 18, 2026
• First Submitted That Met QC Criteria: March 24, 2026
• First Posted (Actual): March 30, 2026

Study Record Updates

• Last Update Posted (Actual): March 30, 2026
• Last Update Submitted That Met QC Criteria: March 24, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Organic Chemicals; Pharmaceutical Preparations; Crystalloid Solutions; Isotonic Solutions; Solutions; Polymers; Macromolecular Substances; Biomedical and Dental Materials; Manufactured Materials; Technology, Industry, and Agriculture; Siloxanes; Organosilicon Compounds; Dimethylpolysiloxanes; Silicones; Simethicone; Saline Solution
• Other Study ID Numbers: 2026-KY-0394-001

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No