Esketamine Combined Pregabalin and Duloxetine for Postherpetic Neuralgia

The investigators aim to investigate whether or not esketamine combined with pregabalin and duloxetine to relieve pain in patients with PHN, and seek a rapid, effective and safe treatment for refractory patients with PHN

Inclusion criteria

• Ages more than 18 years;
• Pain present for more than 3 months after healing of a herpes zoster skin rash;
• Has an average pain score of at least 4 on a Numeric Rating Scale (NRS, 0= no pain, 10= worst possible pain)；
• Failed to respond to or tolerate the effective dose of pregabalin monotherapy.

Exclusion criteria

• Obstructive sleep apnoea syndrome;
• Those who receive interventional treatments;
• A history of systemic immune diseases, organ transplantation, or cancers;
• A history of severe cardiopulmonary, hepatic or renal dysfunction;
• A history of schizophrenia, epilepsy, or myasthenia gravis, delirium;
• Currently using monoamine oxidase inhibitors (MAOIs);
• Having untreated angle-closure glaucoma;
• Those suffering from increased intracranial pressure；
• Comorbid hyperthyroidism or phaeochromocytoma;
• Suspected or confirmed history of drug abuse;
• Having contraindications to esketamine, pregabaline or duloxetine;
• Communication difficulties;
• Women who are preparing for pregnancy, in the pregnancy or lactation period.