Inclusion Criteria:
1. The subjects can understand the procedures and methods of this clinical trial, have given full informed consent, and voluntarily participate and sign the informed consent form.
2. Male or female individuals aged 18 to 65 years old; with a body mass index (BMI) within the range of \[18.0 - 30.0\] kg/m2 (including the critical value).
3. Those who plan to undergo external dissection and internal ligation under general anesthesia.
4. American Society of Anesthesiologists (ASA) classification levels I-II.
5. The subjects must agree to take effective contraceptive measures from after signing the informed consent to 30 days after medication administration.
Exclusion Criteria:
1. The subjects had pain unrelated to hemorrhoid diseases, and the researchers judged that it might confuse the postoperative assessors.
2. Those who planned to undergo surgeries in other parts at the same time.
3. Those with any of the following clinical severe disease histories or current severe diseases: ① respiratory system diseases ② neurological and mental disorders ③ circulatory system diseases ④ blood system diseases ⑤ tumors ⑥ digestive system diseases ⑥ having other diseases that might significantly affect the efficacy evaluation or in vivo metabolism of the test drug.
4. Those who have undergone hemorrhoid resection surgery before.
5. Those with fecal incontinence, perianal abscess, etc.
6. Those with a history of constipation and the researchers judged that it might affect the postoperative pain assessment.
7. Those who had vomiting during the screening period or had a history of severe, refractory postoperative nausea and vomiting.
8. Those who have obvious contraindications to the prescribed medication.
9. Those with clinically significant laboratory test results during the screening period.
10. Those with prolonged QTcF interval during the screening period: male ≥ 450 ms, female ≥ 470 ms.
11. Those who are allergic to any component of the test drug, general anesthesia medication, rescue analgesic medication, antiemetic medication, or have a history of specific reactions.
12. Those who used or were expected to use opioids, NSAIDs, sedative anesthetics, local anesthetics, glucocorticoids, anti-epileptic drugs, anti-anxiety drugs, anti-depressants, drugs with analgesic effect of traditional Chinese medicine/herbs, class III anti-arrhythmic drugs, strong CYP1A2 inhibitors, CYP1A2 highly sensitive substrates, strong CYP3A4 inhibitors, CYP3A4 highly sensitive substrates, strong CYP3A4 inducers within the first 5 half-lives of screening.
13. Those who frequently drink alcohol within 3 months before screening (90 days), that is, those who consume more than 14 units of alcohol per week (1 unit = 360 mL of beer or 45 mL of 40% alcohol liquor or 150 mL of wine).
14. Those who participated in clinical trials of drugs or devices within 3 months before screening and received treatment with the test drug or device.
15. Those who have a history of drug abuse or drug use within the past 1 year.
16. Those whose blood or urine pregnancy test is positive during the screening period, or are in lactation.
17. Those who, in the researcher's opinion, cannot evaluate the efficacy or are unlikely to complete the trial.
