The Efficacy and Safety of Liposomal Bupivacaine in Relieving Postoperative Pain After Hemorrhoid Surgery

Inclusion Criteria: 1. Patients scheduled for elective Hemorrhoid Surgery under general anesthesia; 2. Ages 18 to 64 years old； 3. American Society of Anesthesiologists (ASA) physical status of I-III； 4. Glasgow Coma Scale (GCS) score of 15； 5. Patients must be able to understand the nature and potential personal consequences of the clinical trial, signing of the informed consent form. Exclusion Criteria: 1. History of chronic pain syndrome of any cause. 2. Patients with heart conduction block (sinus block or atrioventricular block). 3. Patients with unstable coronary artery disease. 4. Patients with gastric ulcer or gastric bleeding. 5. Patients with diabetes and are being treated with insulin. 6. Subjects with coagulation dysfunction (prothrombin time or activated partial thromboplastin time is higher than the normal threshold) or patients who are taking oral anticoagulants for other medical reasons and have not stopped it before surgery, such as warfarin or new anticoagulants rivaroxaban or dabigatran. 7. Patients with abnormal liver function: alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) \> 2× the upper limit of normal (ULN) or total bilirubin (TBIL) ≥ 1.5×ULN. 8. Patients with renal impairment (serum creatinine \> 176 µmol/L) or receiving dialysis treatment within 28 days before surgery. 9. Patients with a history of diagnosed mental illness or currently taking psychotropic medication. 10. Excessive alcohol or drug abuse, chronic opioid use (more than 2 weeks or 3 days per week for more than 1 month), use of drugs with confirmed or suspected sedative or analgesic effects, or use of any painkiller within 24 h before surgery. 11. Pregnancy or breastfeeding. 12. Extreme body mass index (BMI) (\< 15 or \> 35). 13. Participation in another interventional trial that interferes with the intervention or outcome of this trial. 14. Patients with a history of allergy to local anaesthetics or one of the study drugs.