This clinical trial is a multiple-center, randomized, double-blind, placebo- and active-controlled parallel-group Phase II/III clinical trial, to evaluate the efficacy and safety of HL-1186 Tablets for Postoperative Analgesia in Abdominal Surgery.

Inclusion Criteria:

1. 18 years old ≤ age ≤ 75 years old, gender is not limited.
2. 18 kg/m2 ≤ Body Mass Index (BMI) ≤ 30kg/m2.
3. Scheduled to undergo abdominal surgery under general anesthesia, with expected moderate-to-severe postoperative pain intensity.
4. Able to understand the research process and the use of pain scales, and communicate effectively with researchers.
5. After surgery completion, the participant is judged by the investigator to be awake and has a resting NRS score ≥ 4.

Exclusion Criteria:

1. Previous surgery on the same site that may affect pain perception at the surgical site.
2. Paresthesia or other pain that may affect postoperative pain evaluation or scale assessment.
3. Neuropsychological disorders that may affect postoperative pain evaluation or scale assessment.
4. Unstable angina, myocardial infarction, severe arrhythmia, NYHA cardiac function class ≥ III, or recurrent asthma attacks, etc., deemed unsuitable for inclusion by the investigator.
5. Poorly controlled hypertension.
6. Sleep apnea syndrome, or the presence of a difficult airway as assessed by the investigator.
7. Known allergy to any component of the investigational drug(s), to perioperative (from induction of anesthesia to completion of surgery) anesthetic/analgesic/antiemetic drugs, or a history of allergy to ≥ 3 substances.
8. Positive for human immunodeficiency virus (HIV) antibody; positive for Treponema pallidum antibody and positive toluidine red unheated serum test (TRUST); positive for hepatitis B surface antigen (HBsAg) with detectable HBV-DNA; or positive for hepatitis C virus (HCV) antibody.
9. Women who are pregnant or breastfeeding (within 1 year after delivery).
10. Participation in another drug or medical device trial within 1 month before screening, or currently participating in another clinical trial receiving investigational intervention.
11. Any other condition considered unsuitable for participation by the investigator.