Intranasal Esketamine-dexmedetomidine Combination in Patients With Postherpetic Neuralgia

实验性的：DEX-ESK group

For each administration: dexmedetomidine (1 spray = 0.05 ml = 25 μg) is administered as one spray into each nostril; after 1 minute, esketamine (1 spray = 0.05 ml = 1.25 mg) is administered alternately into each nostril, 4 sprays per nostril. Esketamine administration is repeated every 5 minutes until a total dose of 0.3 mg/kg is reached (using the number of sprays closest to the predetermined dose). If a dose is not tolerated, one administration may be omitted.

Administer once daily for 4 consecutive days, with the same administration method as above.

药品：Intranasal DEX-ESK combination

For each administration: dexmedetomidine (1 spray = 0.05 ml = 25 μg) is administered as one spray into each nostril; after 1 minute, esketamine (1 spray = 0.05 ml = 1.25 mg) is administered alternately into each nostril, 4 sprays per nostril. Esketamine administration is repeated every 5 minutes until a total dose of 0.3 mg/kg is reached (using the number of sprays closest to the predetermined dose). If a dose is not tolerated, one administration may be omitted.

Administer once daily for 4 consecutive days, with the same administration method as above.

其他名称：

• Intranasal dexmedetomidine and esketamine

有源比较器：ESK group

For each administration: placebo (0.9% saline; 1 spray = 0.05 ml) is administered as one spray into each nostril; after 1 minute, esketamine (1 spray = 0.05 ml = 1.25 mg) is administered alternately into each nostril, 4 sprays per nostril. Esketamine administration is repeated every 5 minutes until a total dose of 0.3 mg/kg is reached (using the number of sprays closest to the predetermined dose). If a dose is not tolerated, one administration may be omitted.

Administer once daily for 4 consecutive days, with the same administration method as above.

药品：Intranasal ESK alone

For each administration: placebo (0.9% saline; 1 spray = 0.05 ml) is administered as one spray into each nostril; after 1 minute, esketamine (1 spray = 0.05 ml = 1.25 mg) is administered alternately into each nostril, 4 sprays per nostril. Esketamine administration is repeated every 5 minutes until a total dose of 0.3 mg/kg is reached (using the number of sprays closest to the predetermined dose). If a dose is not tolerated, one administration may be omitted.

Administer once daily for 4 consecutive days, with the same administration method as above.

其他名称：

• Intranasal placebo (normal saline) and esketamine

Sum of pain intensity difference (SPID) within 7 days after the first administration

Follow-up time points: before each administration (Days 1, 2, 3, and 4 of enrollment; face-to-face follow-up); on Days 1, 2, and 3 after the last administration (Days 5, 6, and 7 of enrollment; telephone follow-up at the same time of day as drug administration).

Pain intensity: the patient's NRS pain score over the past 24 hours is recorded (0-10; 0 = no pain at all, 10 = the worst pain imaginable).

Sum of pain intensity difference (SPID): calculated as the sum of (baseline NRS score - NRS score at each scheduled daily follow-up) within 7 days after the first administration (i.e., 3 days after the last treatment).

Sum of pain intensity difference (SPID) during Weeks 2 to 12 after the first administration

Follow-up time points: once weekly after the last administration until Week 12 of enrollment (Days 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 of enrollment; telephone follow-up).

Pain intensity: the patient's NRS pain score over the past 24 hours is recorded (0-10; 0 = no pain at all, 10 = the worst pain imaginable).

Sum of pain intensity difference (SPID): calculated as the sum of (baseline NRS score - NRS score at each scheduled weekly follow-up) during Weeks 2 to 12 after the first administration.

Change from baseline in ZBPI chronic pain and impact scores within 3 months after treatment

Follow-up time points: Days 7 and 14 after the first administration (telephone follow-up); Months 1, 2, and 3 after the first administration (Days 28, 56, and 84 of enrollment; telephone follow-up).

Severity of chronic pain and its impact on patients: assessed using the Zoster Brief Pain Inventory (ZBPI, Appendix 7). Pain severity is rated from 0 to 10, with higher scores indicating greater pain severity; pain interference is rated from 0 to 10 across 7 domains, with higher scores indicating greater interference with daily functioning.

Within 3 months after the first dose