Investigate the Efficacy and Safety of HSK16149 capsules in Chinese Postherpetic Neuralgia Following 12 Weeks Treatment in Comparison to Placebo

Inclusion Criteria:

1. Signed informed consent;
2. Males or females aged 18-75 years of age inclusive;
3. Outpatient, Patients can not stay in the hospital overnight;
4. Patients must have pain present for more than 1 months after the healing of the herpes zoster skin rash;
5. At Screening, pain scale (VAS) of ≥40 mm;

Exclusion Criteria:

1. Peripheral neuropathy or pain unrelated to PHN that may confuse the assessment of PHN;
2. Skin conditions in the area affected by neurupathy that could alter sensation;
3. Chronic systemic diseases that may affect subjects' participation in the study;
4. Severe hematologic, hepatic or renal dysfunction, the subject will be excluded if:1)Neutrophils < 1.5 × 109/L, or platelet < 90 × 109/L, or hemoglobin < 100 g/L, or 2)AST/ALT > 2.5 × upper limit of normal (ULN), or TBIL > 1.5 × ULN, or 3)Estimation of glomerular filtration rate (eGFR) < 60 mL/min / 1.73 m2, or 4)Creatine kinase > 2.0 × ULN.
5. Uncontrolled diabetes(HbA1c≥11.0% at screening) ;
6. History of substance abuse or alcohol abuse;
7. Any active infections at screening;
8. HBsAg or HCV Ab positive, or HIV Ab positive, or serum TP Ab positive;
9. Inability or unwillingness to discontinue any other prohibited concomitant medications (see Section 6.3);
10. Patients who have undergone neurolytic or neurosurgical therapy 1 week before screening for postherpetic neuralgia;
11. Failure to response to previous treatment with pregabalin at doses ≥ 300 mg/d or gabapentin at doses ≥ 1200 mg/d for treatment of PHN;
12. History of allergic or medically significant adverse reaction to investigational products or their excipients, acetaminophen or related compounds;
13. History of suicidal behavior or attempted suicide;
14. Pregnant or preparing for pregnancy or breastfeeding during the study period, or subjects were not willing to use reliable contraceptives methods from the date of ICF signature until 28 days after the last trial drug administration, or planning to use progesterone contraceptives during this period;
15. Mechanical operators who are engaged in high-altitude operations, motor vehicle driving and other dangerous machinery operators;
16. Participated in another clinical study within 30 days prior to screening;
17. Other conditions unlikely to participate in this trial.