Supplementary Material for: Efficacy of Gabapentin Combined with Standard-dose Antihistamines versus Antihistamine Monotherapy in Prurigo Nodularis: A Prospective Monocentric Real-world Observational Study

Introduction: Prurigo nodularis (PN), the most common subtype of Chronic prurigo, is a chronic pruritic dermatosis. Although gabapentin has been proposed as a second-line treatment for PN, clinical studies assessing its efficacy and safety for PN remain limited. This study evaluated the efficacy and safety of gabapentin in the management of PN and to explore an effective and well-tolerated dosing regimen.
Methods: In the 12-week prospective real-world observational study, 26 patients with PN were allocated to receive either gabapentin (initial dose 300 mg/day) combined with standard-dose antihistamines (combination group) or standard-dose antihistamine monotherapy (monotherapy group). Dose adjustments of gabapentin were made depending on therapeutic response biweekly, with a maximum of 900 mg daily. Efficacy was assessed using the Peak Pruritus Numerical Rating Scale (PP-NRS), Sleep Disturbance-Numerical Rating Scale (SD-NRS), Dermatology Life Quality Index (DLQI), and Hospital Anxiety and Depression Scale (HADS), and Investigator's Global Assessment (IGA) scores. Itching response was defined as a reduction of the PP-NRS scores that is greater than 50% or 4 points compared with baseline.
Results: Compared to monotherapy group (n=14), the combination group (n=12) exhibited significantly lower PP-NRS and HADS scores as early as week 2, and a higher proportion of patients showing itching response (75.0% vs. 35.7%). The majority (77.8%) of patients in the combination group reached the itching response at week 12 under 600 mg of gabapentin daily. Adverse effects were mild and resolved following dose reduction.
Conclusion: Gabapentin provides faster and superior efficacy in reducing pruritus and anxiety and depression for patients with PN, with a favorable safety profile.