Inclusion Criteria:
1. Voluntarily sign the informed consent form prior to the start of any trial-related activities, fully understand the purpose and significance of the study, and voluntarily comply with the trial procedures;
2. 2、Scheduled to undergo elective surgery under general anesthesia with an expected surgical duration of ≥ 2 hours (surgery types include gynecological surgery, hepatobiliary surgery, intestinal surgery, urological surgery, etc.);
3. Aged ≥ 18 years;
4. Body Mass Index (BMI) between 18 kg/m² and 28 kg/m² (inclusive);
5. American Society of Anesthesiologists (ASA) Physical Status Classification I or II;
6. Expected postoperative hospital stay ≥ 72 hours;
7. Presence of ≥ 3 risk factors for PONV (female, history of PONV or motion sickness, non-smoker, postoperative opioid use);
8. Female participants of childbearing potential must have a negative serum pregnancy test within 7 days prior to randomization and must not be breastfeeding; female participants of childbearing potential must use highly effective contraceptive measures (see Appendix 13.1.2) from 30 days prior to the screening period until 6 months after the last dose, and have no plans for egg donation or pregnancy; male participants with a female partner of childbearing potential must use highly effective contraceptive measures from the time of signing the informed consent form until 6 months after the last dose.
Exclusion Criteria:
1. Patients with a history of vestibular disorders (including but not limited to: peripheral vestibular syndrome, central vestibular syndrome, etc.) or dizziness (excluding history of motion sickness), or a history of central nervous system disorders that may cause nausea and vomiting;
2. History of chronic nausea or vomiting/retching;
3. History of new-onset myocardial infarction or unstable angina pectoris within 6 months prior to screening, or history of severe cardiac arrhythmias such as second-degree or higher atrioventricular block, or history of New York Heart Association (NYHA) Functional Classification Class II or higher;
4. Any other medical condition that, in the investigator's judgment, may confound the assessment of postoperative nausea and/or vomiting.
5. Random blood glucose \> 11.1 mmol/L during the screening period;
6. Prolonged QTc interval during the screening period: \> 450 ms in males, \> 470 ms in females;
7. Systolic blood pressure ≥ 160 mmHg or \< 90 mmHg, and/or diastolic blood pressure ≥ 100 mmHg or \< 60 mmHg from the time of signing the ICF to before entering the operating room, which is considered clinically significant by the investigator;
8. Abnormal liver function during the screening period: aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) and/or gamma-glutamyl transferase (GGT) ≥ 3.0 × ULN and/or total bilirubin (TBIL) ≥ 1.5 × ULN;
9. Abnormal renal function during the screening period: serum creatinine (Cr) ≥ 1.5 × ULN and/or participants undergoing dialysis;
10. Positive test for hepatitis B surface antigen (HBsAg), hepatitis C antibody (HCVAb), syphilis antibody, or human immunodeficiency virus (HIV) antibody during the screening period;
11. Known allergy or contraindication to NK-1 receptor antagonists and/or 5-HT3 receptor antagonists and other medications that may be used during the trial;
12. Receipt of any treatment with potential antiemetic effects, including pharmacological and non-pharmacological treatments, within 48 hours prior to the start of investigational product administration (refer to the Prohibited Concomitant Treatments table);
13. Participants whose last use of an opioid occurred less than 5 half-lives before the start of investigational product administration;
14. Use of strong CYP3A4 inducers, strong inhibitors, or specific CYP2D6 substrates within 28 days prior to randomization.
15. Participants who have received chemotherapy within 4 weeks prior to surgery;
16. Use of other medications that may affect antiemetic efficacy as determined by the investigator, with the last use occurring less than 5 half-lives before the start of investigational product administration (based on the actual drug label; if the half-life is unknown, a 48-hour washout period should be applied).
17. Participants scheduled to receive anesthetic methods not specified in the protocol, including local anesthesia, regional anesthesia \[e.g., nerve block, neuraxial block (including subarachnoid block, epidural anesthesia, or combined spinal-epidural anesthesia)\], and total intravenous anesthesia;
18. Participants expected to require an in-place nasogastric tube or orogastric tube after surgery completion;
19. Participants expected to be transferred to the ICU for sedation with endotracheal intubation after surgery or those unable to undergo nausea and vomiting record assessments;
20. Participation in another clinical study of a drug or device within 3 months prior to screening (having signed informed consent and received investigational product/device treatment);
21. Daily excessive consumption of tea, coffee, grapefruit/grapefruit juice, pomelo juice, or caffeinated beverages (average \> 8 cups per day, 200 mL per cup) within 14 days prior to randomization;
22. Any other condition that, in the investigator's opinion, makes the participant unsuitable for participation in this trial.
