A Trial of HR18034 for Postoperative Analgesia in Subjects Undergoing Hemorrhoidectomy.

Inclusion Criteria: 1. Able and willing to provide a written informed consent 2. Subjects requiring hemorrhoidectomy under subarachnoid anesthesia 3. 18 kg/m2 ≤ BMI ≤ 28 kg/m2 4. Conform to the ASA Physical Status Classification 5. Women of childbearing age have a negative pregnancy test and are not nursing Exclusion Criteria: 1. Subjects with a history of myocardial infarction or unstable angina pectoris 2. Subjects with atrioventricular block or cardiac insufficiency 3. Subjects with a history of ischemic stroke or transient ischemic attack 4. Subjects with a history of mental illness and a history of cognitive impairment epilepsy 5. Subjects with concurrent painful physical condition that may affect postoperative pain assessment 6. Subjects with myelopathy or spinal disease 7. Subjects with a history of hemorrhoidectomy 8. Abnormal values in the laboratory 9. Subject with a history of substance abuse and drug abuse 10. Subject with refractory hypertension 11. History of hypersensitivity or idiosyncratic reactions to amide-type local anesthetics, opioids, or other drugs that may used in study 12. History of substance abuse, drug use and/or alcohol abuse 13. HBsAg, HCVAb, HIV antibody and syphilis antibody tested positive during screening period; 14. Participated in clinical trials of other drugs (received experimental drugs) 15. The inestigators determined that other conditions were inappropriate for participation in this clinical trial