HSK16149 for Perioperative Analgesia in Orthopedic Surgery

Inclusion Criteria: 1. Male or female between the ages of 18 and 75 years (included); 2. Elective orthopedic surgery under general anesthesia, expected operation time ≤4 hours and postoperative morphine analgesia time ≥24 hours; 3. 18kg/m\^2≤BMI≤30 kg/m\^2; 4. American Society of Anesthesiologists (ASA) grade I and II; Exclusion Criteria: 1. Any of the following medical histories or conditions prior to screening: * Long history of chronic pain; * history of severe cardiovascular or respiratory disease; * history of neurological or psychiatric disorders; * history of acute poisoning with alcohol, hypnotics, analgesics or other drugs acting on the central nervous system; * major surgery within 3 months; * patients with high bleeding risk; * history of renal disease treated with dialysis within 28 days before surgery; * have active infection within the past 2 weeks; 2. Use of any of the following medications or treatments: * opioid analgesics for more than 10 consecutive days within 3 months prior to screening; * other analgesics before randomization if the last dose was taken less than 5 half-lives of the drug (according to the label); 3. Abnormal laboratory tests during screening: 4. Hypertension that is not adequately controlled by antihypertensive drugs (systolic blood pressure ≥160 mmHg and/or diastolic blood pressure ≥100 mmHg), or systolic blood pressure ≤90 mmHg during screening; 5. A history of drug abuse, and/or alcohol abuse in the 3 months prior to screening; 6. Participated in another clinical trial and received IMP within 30 days prior to screening; 7. Pregnant or lactating women; 8. Unwillingness to use reliable contraceptive methods from the time of screening until 28 days after the last dose of IMP;