The study is being conducted to evaluate the efficacy, and safety 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 ≤ 30 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. Spinal or spinal lesions that were determined by the investigator to be unable to tolerate subarachnoid anesthesia
7. Subjects with a history of hemorrhoidectomy
8. Subjects with a history of constipation
9. Subjects with a history of perianal disease
10. Abnormal values in the laboratory
11. Subject with heart rate <50 or >100 beats per minute.
12. Subject with refractory hypertension
13. History of hypersensitivity or idiosyncratic reactions to amide-type local anesthetics, opioids, or other drugs that may used in study
14. History of prohibited drug use
15. Participants who may be affected by alcohol, or drug abstinence during the study period;
16. Participated in clinical trials of other drugs (received experimental drugs)
17. The inestigators determined that other conditions were inappropriate for participation in this clinical trial