Gastroretentive Gabapentin (G-GR) Formulation Reduces Intensity of Pain Associated With Postherpetic Neuralgia (PHN)

OBJECTIVE:To evaluate the safety and efficacy of a once-daily gastroretentive formulation of gabapentin (G-GR; 1800 mg). METHODS:This was an 11-week, double-blind, randomized, placebo-controlled Phase 3 clinical trial in patients with postherpetic neuralgia. Patients underwent a 2-week dose titration, 8 weeks of stable dosing, and 1 week of dose tapering. The primary endpoint was the change in average daily pain intensity score from Baseline to Week 10 using Baseline Observation Carried Forward (BOCF) imputation. RESULTS:Four-hundred and fifty-two patients (mean age 65.6 y, BMI 29 Kg/m) were randomized. Baseline average daily pain intensity score during the week prior to randomization was 6.6 and 6.5 for the G-GR and placebo treatment groups, respectively. Three hundred and seventy-seven patients completed the study (84% G-GR, 83% placebo). G-GR significantly reduced BOCF change in average daily pain intensity compared with placebo (−2.1 vs. −1.6; G-GR vs. placebo, P=0.013). Compared with placebo, more G-GR-treated patients reported “much” or “very much” improvement (patient global impression of change, 43% vs. 34%; P