Efficacy and Safety of Intravenous Meloxicam in Subjects With Moderate-to-severe Pain Following Abdominal Surgery

1. Male or female between 18 and 75 years of age, inclusive.
2. Be scheduled to undergo abdominal surgery under general anesthesia with anticipated moderate to severe postoperative pain.
3. Be American Society of Anesthesiology (ASA) physical class 1 or 2.
4. Be able to understand the pain intensity evaluation methods.
5. 18kg/m\^2\<body mass index ≤30 kg/m\^2.
6. Female Participants must not be pregnant or lactating. Participants(including their partners)must agree to use appropriate contraception from the time of signing the informed consent form until 3 months after the last dose.No plans for sperm or egg donation during the study period.
7. Be able to understand the study purpose and procedures, agree to participate in the study program, Voluntarily provide written informed consent.

Exclusion Criteria:

1. Have a known allergy to meloxicam or any excipient of meloxicam, aspirin, other non-steroidal anti-inflammatory drugs (NSAIDs) or to any peri- or postoperative medications used in this study.
2. Have a history or clinical manifestations of significant cerebrovascular, respiratory, renal, hepatic, endocrine, neurological, psychiatric systemic diseases, or advanced malignant tumors, and judged by the investigator as unsuitable for participation in this study.
3. Have a history of migraine, anxiety,seizures, cognitive dysfunction, or other psychiatric or neurological disorders that the investigator believes may interfere with the study evaluation.

4. Participants with the following cardiovascular diseases or history:

   1. Severe cardiovascular diseases, NYHA heart function class II or above, myocardial infarction, angina, or coronary artery bypass grafting (CABG) within the preceding 12 months, severe arrhythmias, or abnormal ECG during the screening period judged by the investigator as unsuitable for participation in this study.
   2. Resting systolic blood pressure ≥160mmHg in a sitting or lying position, and/or diastolic blood pressure ≥100mmHg during the screening period, from the signing of the informed consent to before anesthesia induction.
   3. Clinically significant respiratory insufficiency, hypotension, bradycardia occurring intraoperatively or postoperatively before randomization, judged by the investigator as unsuitable for participation in this study.
5. Have another painful physical condition judged by the investigator that may confound the assessments of post operative pain.
6. Have (within 12 months) gastrointestinal ulceration, erforation, gastrointestinal bleeding, or abdominal surgery before the screening period judged by the investigator as unsuitable for participation in this study.
7. Have a known bleeding disorder or be taking agents affecting coagulation judged by the investigator as unsuitable for participation in this study.
8. Participants at high risk of bleeding, including those with congenital bleeding disorders (e.g., hemophilia), thrombocytopenia (platelet count below 0.75× the lower limit of normal), or abnormal platelet function (e.g., idiopathic thrombocytopenic purpura, disseminated intravascular coagulation, congenital platelet dysfunction).
9. ALT or AST >2 ULN, TBIL >1.5 ULN, PT >ULN+3s, APTT ≥ULN+10s, Cr ≥1.5×ULN during the screening period, or any laboratory abnormalities judged by the investigator at screening and/or before surgery that may increase the risk of participation.
10. Blood glucose ≥11.1mmol/L from the screening period to before anesthesia induction.
11. Use of the following drugs (not exceeding 5 half-lives of the drug) before randomization, except for anesthetics and sedative/analgesic drugs used preoperatively for invasive examinations as allowed by the protocol: NSAIDs (including compound preparations containing NSAIDs), opioids, anesthetics, sedatives, hypnotics, anticonvulsants, antipsychotics, other central nervous system inhibitors with analgesic effects, and glucocorticoids (excluding topical and inhaled medications).
12. Use traditional Chinese medicines or proprietary Chinese medicines that could interfere with the evaluation of efficacy or safety judged by the investigator.
13. Have been receiving or have received opioid therapy defined Long-term use (continuous use ≥3 days) of opioid analgesics within 14 days before the screening period.
14. Have a history of alcohol abuse (regularly drinks > 14 units of alcohol per day: 1 unit = 360mL beer or 45mL of 40 % spirits or 150mL wine) within the past 2 years or a history of acute alcohol intoxication, alcohol dependence, drug abuse.
15. Have received any drug/device clinical trials within 3 months before dosing with study medication.
16. Have other conditions that make the subject unsuitable for participation in the clinical study in the opinion of the investigator.