Efficacy and Safety of SIKD1977 in Combination with Standard Treatment for Postherpetic Neuralgia: Study Protocol for a Double Blind, Placebo-Controlled, Randomized, Multicenter, Phase 2 Clinical Trial.

Purpose: Postherpetic neuralgia (PHN) is the most common chronic complication of herpes zoster, associated with poor quality of life and increased patient and healthcare resource expenditure. This randomized controlled trial aims to evaluate the efficacy and safety of SIKD1977 (Sogeonjungtang) in combination with standard treatment and estimate an effective dose for treating PHN. Patients and Methods: This is a protocol for a randomized, placebo-controlled, double-blind, multicenter trial. A total of 90 eligible participants with PHN will be recruited from three hospitals and randomly allocated to high-dose group, low-dose group, or placebo group in a 1:1:1 ratio. The trial will involve a 6-week oral administration of SIKD1977/placebo, and a 1-week follow-up period. The primary outcome will be the weekly average change in average daily pain score (ADPS) from baseline to the end of treatment. The secondary outcomes will include the weekly average changes in ADPS from baseline to week 2, 4, and 7, differences in Short-Form McGill Pain Questionnaire, Visual analogue scale, 5-level EuroQol-5 dimensions, Patient Global Impression of Change, and consumption of rescue drugs. All adverse events will be assessed during the trial. Conclusion: This study will provide evidence for the efficacy and safety of SIKD1977, and an effective dose for PHN. Trial Registration: This protocol has been registered in the Clinical Research Information Service with the identification code KCT0007939.