The study is being conducted to evaluate the efficacy, and safety of HR18034 for postoperative analgesia in subjects undergoing hemorrhoidectomy. To explore the reasonable dosage 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