Chinese patients who require gastrointestinal endoscopy will receive an intra-gastric single dose of NPO-11 20ml. The superiority of NPO-11 compared to placebo as a premedication for endoscopy will be verified in a randomized, double-blind, parallel-assignment design based on the proportion of patients having no gastric peristalsis.

The safety of NPO-11 will be evaluated based on adverse events and adverse drug reactions observed between informed consent and 7 days after administration in comparison with the placebo group.

Inclusion Criteria:

1. Patients who are capable of understanding and complying with protocol requirements in the opinion of the investigator or the sub-investigator.
2. Patients who are able to fill in the informed consent form.
3. Patients who require gastrointestinal endoscopy using a scope of 9mm or greater diameter for follow-up of confirmed or investigation of a suspected upper gastrointestinal disease. (except for transnasal endoscopy and emergency endoscopy)
4. Male or female chinese patients aged _18_ to _80
5. Patients who agree to use routinely adequate contraception from signing of informed consent to follow-up.

Exclusion Criteria:

1. Patients have received any investigational drug of other study within 120 days prior to providing their informed consent.
2. Patients had been administered NPO-11 in the past.
3. Patients who are the study site investigator or sub-investigator, an immediate family member (eg, spouse,parent, child, sibling), or may consent under duress.
4. Patients have a history of upper gastrointestinal tract surgery.
5. Patients have gastric stenosis or deformity that would make observation of peristaltic movement difficult.
6. Patients have bleeding in the upper gastrointestinal tract and require hemostatic intervention.
7. Patients have reflux esophagitis (defined as Los Angeles Class: B, C or D)
8. Patients have an active gastric or duodenal ulcer (defined as Sakita-Miwa class: A1 or A2)
9. Patients are on treatment (radiotherapy or chemotherapy) for cancer.
10. Patient have decreased heart function (NYHA heart function class: III or more)
11. Patients have a history of shock, hypersensitivity or allergies to l-menthol or peppermint oil.
12. Patients have a history of drug abuse (defined as any illicit drug use) or a history of alcohol abuse within 12 months prior to the screening visit.
13. Patients are required to take excluded medications.
14. If female, patients are pregnant or lactating or intending to become pregnant from signing of informed consent to follow-up.
15. Any subject who, in the opinion of the investigator or the sub-investigator, is unable to comply with the requirements of the study or is unsuitable for any reason.