Esketamine Combined Pregabalin and Duloxetine for Postherpetic Neuralgia

Inclusion Criteria:

1. Ages more than 18 years;

2. Pain present for more than 3 months after healing of a herpes zoster skin rash;

3. Has an average pain score of at least 4 on a Numeric Rating Scale (NRS, 0= no pain, 10= worst possible pain)；

4. Failed to respond to or tolerate the effective dose of pregabalin monotherapy.

Exclusion Criteria:

1. Obstructive sleep apnoea syndrome;

2. Those who receive interventional treatments;

3. A history of systemic immune diseases, organ transplantation, or cancers;

4. A history of severe cardiopulmonary, hepatic or renal dysfunction;

5. A history of schizophrenia, epilepsy, or myasthenia gravis, delirium;

6. Currently using monoamine oxidase inhibitors (MAOIs);

7. Having untreated angle-closure glaucoma;

8. Those suffering from increased intracranial pressure；

9. Comorbid hyperthyroidism or phaeochromocytoma;

10. Suspected or confirmed history of drug abuse;

11. Having contraindications to esketamine, pregabaline or duloxetine;

12. Communication difficulties;

13. Women who are preparing for pregnancy, in the pregnancy or lactation period.