This study will investigate the safety, efficacy and dose-response of NPO-13 in subjects with moderate to severe colonic spasm during colonoscopy. An intraluminal spraying of NPO-13 dosed up to twice into ascending or sigmoid colon. The colonic spasm will be assessed by an independent committee using recorded video images. The study consists of a screening visit window, 1-day treatment phase and 1-week follow-up phase.

Inclusion Criteria:

1. Patients who are between 20 and 85 years at the time of consent
2. Patients who need colonoscopy

Exclusion Criteria:

1. Patients with a history of abdominal surgical treatment (including the laparoscopic surgery) including the gynecology operation
2. Patients with contraindication to colonoscopy including the paralytic ileus
3. Patients with a history of shock or hypersensitivity to l-menthol or peppermint oil (mint oil)
4. Patient with contraindication to bowel cleansing preparation
5. Patient with contraindication to pain medicine and sedative medicine
6. Patient with contraindication to butylscopolamine bromide and glucagon
7. Patients on cancer treatment (chemotherapy or radiotherapy)
8. Patient with active inflammatory bowel disease or infectious enteritis
9. Patients who need sedative in colonoscopy
10. Patients who receives a therapeutic colonoscopy
11. Pregnant or lactating women, women of childbearing potential, or women who plan to become pregnant during the study
12. Patients who have received other investigational drugs within four months before consent or who are participating in other clinical studies
13. Patients otherwise ineligible for participation in the study in the investigator's or coinvestigator's opinion