A Study of YZJ-4729 Tartrate Injection for the Treatment of Pain After Orthopedic Surgery

Inclusion Criteria: 1. Be able to understand the study purpose and cooperate with the study procedures of this trial, voluntarily provide written informed consent 2. BMI≥18.0 kg/m2 and ≤28.0 kg/m2 3. ASA I to II 4. Experiences a pain intensity rating of moderate to severe acute pain following orthopedic surgery, with a pain intensity score of ≥4 on a Numeric Rating Scale (NRS) within 4 hours post-surgery Exclusion Criteria: 1. Opioid allergy 2. Nervous system diseases (e.g. epilepsy) 3. Psychiatric disorders (e.g. depression) 4. History of difficult airways 5. Random blood glucose ≥11.1 mmol/L 6. Subjects with systolic blood pressure \>160 mmHg and/or diastolic blood pressure \>100 mmHg or systolic blood pressure \< 90 mmHg 7. Abnormal pulse oxygen saturation (SpO2 \<92 %) 8. Abnormal liver function or renal function 9. Used agents that could affect the analgesic response 10. Used agents that could affect drug metabolism 11. Has previously participated in another YZJ-4729 clinical study