Evaluate the Analgesic Efficacy and Safety of VVZ-149 Injection for Post-operative Pain Following Gastrectomy

Inclusion Criteria: 1. Patient between the ages of 25 and 70 years old 2. Male patient, in the case of female patient, postmenopausal women, or women physically incapable of childbearing 3. Subject who underwent surgery specially for the clinical study 4. Ability to provide written informed consent prior to any study procedures. 5. Ability to understand study procedures and communicate clearly with the investigator and staff. 6. Subjects with body weight under 100kg and body mass index (BMI) level lower than 35 kg/m2, inclusive Exclusion Criteria: \< Surgical Factors \> 1. Emergency or unplanned surgery. 2. Repeat operation (e.g., previous surgery within 30 days for same condition). 3. Cancer-related condition causing preoperative pain in site of surgery. \< Subject Characteristics \> 4. Women with childbearing potential, Women who are pregnant or breastfeeding. 5. Chronic pain diagnosis (e.g., ongoing pain at baseline with NRS ≥ 4/10). 6. Unstable or poorly controlled psychiatric condition (e.g., untreated PTSD, anxiety, or depression). Subjects who take stable doses (same dose \>30 days) of antidepressants and anti-anxiety drugs may be included. 7. Unstable or acute medical condition (e.g., unstable angina, congestive heart failure, renal failure, hepatic failure, AIDS). 8. Subjects who have long PR (\>200msec) or prolonged QTc (\> 450msec in male, \>470msec in female) at Screening \< Drug, Alcohol, and Pharmacological Considerations \> 9. History of alcohol, opiate or other drug abuse or dependence within 12 months prior to Screening . 10. Ongoing or recent (within 30 days prior to surgery) use of steroids, opioids, or antipsychotics. 11. Alcohol consumption within 24 hours of surgery. 12. Use of nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen within 24 hours of surgery. 13. Use of herbal agents or nutraceuticals (i.e., chaparral, comfrey, germander, jin bu huan, kava, pennyroyal, skullcap, St. John's wort, or valerian) within 7 days prior to surgery. \< Anesthetic and Other Exclusion Considerations \> 14. Use of neuraxial or regional anesthesia related to the surgery. 15. Use of ketamine, gabapentin, pregabalin, or lidocaine (\>1 mg/kg) intra or peri-operatively, or within 24 hours of surgery. 16. Subject with known allergies to hydromorphone. 17. Subjects who received another investigational drug within 30 days of scheduled surgery