A phase Ib randomized, double-blind, positive-parallel controlled trial to evaluate the efficacy, safety, and pharmacokinetic characteristics of HYR-PB21 paravertebral nerve block for injection for analgesia in patients with postherpetic neuralgia (PHN)

INTERVENTION: Arm A:HYR‐PB21 for injection 200mg; 20ml;Arm B:Bupivacaine hydrochloride injection 50mg; 20ml; CONDITION: Peripheral nerve block PRIMARY OUTCOME: NRS was used to evaluate pain intensity scores within 72 hours after treatment; INCLUSION CRITERIA: 1. The subjects who can understand the procedures and methods of this clinical trial (including pain intensity assessment method) voluntarily participate in the trial after full informed consent, and the informed consent form is signed by the subjects themselves or their legal guardian; 2. The informed consent of patients aged 18 ‐ 75 years, regardless of gender; 3. In patients with clinical diagnosis of postherpetic neuralgia, the distribution area of herpes zoster was in the innervation area of one thoracic spinal ganglion segment, and the number of involved ganglion segments was less than or equal to 3; 4. Patients with pain intensity score (NRS) >= 4 at screening stage and before enrollment; 5. Female or male subjects of childbearing age should agree to take effective contraceptive measures by themselves and their partners within 30 days after signing the informed consent.