Safety and efficacy of gastroretentive gabapentin in real-world clinical practice for treatment of elderly patients with postherpetic neuralgia (PHN)

This Phase 4 open-label study evaluated the safety and effectiveness of once-daily gastroretentive gabapentin (G-GR) for treatment of PHN in real-world clinical practice settings. Patients aged ≥18 years were divided into 2 cohorts: patients ≤70 years and patients >70 years. All patients were titrated to 1800 mg G-GR/day over 2 weeks and maintained at that dosage for 6 weeks, for 8 weeks of total treatment. To reflect clinical practice, exclusion criteria were limited to those in the product label. Efficacy was assessed using a visual analog scale (VAS) and the Brief Pain Inventory (BPI). Patient Global Impression of Change (PGIC) and Clinician Global Impression of Change (CGIC) scales were completed at Week 8. Treatment-emergent adverse events (TEAEs) were assessed. The efficacy population included 190 patients, 110 in the ≤70 years group and 80 in the >70 years group. The mean percent change in VAS score at Week 8 from Baseline was -21.3%/-20.4% (≤70 years/>70 years). The proportion of responders by VAS score (≥30% reduction from Baseline) was 51.8%/55.0% (≤70 years/>70 years). Patients with ≥50% reduction in VAS score from Baseline were 42.7%/37.5% (≤70 years/>70 years). BPI subscores, including interference scores, were all significantly reduced by Week 8 in both age groups. At Week 8, using the PGIC instrument, 59.0%/40.3% (≤70 years/>70 years) of patients considered their symptoms “Very much” or “Much” improved relative to Baseline. G-GR was generally well tolerated. Thirty-seven (18.8%) patients experienced TEAEs that led to study discontinuation. No patients died and 5 (2.5%) patients experienced serious TEAEs; none was considered to be related to treatment with G-GR by investigators. The most common G-GR-related TEAEs (≤70 years/>70 years) were dizziness (11.7%/16.3%) and somnolence (3.6%/8.1%). Thus, in real-world clinical practice, G-GR appears to be an effective, well tolerated treatment option for patients with PHN, regardless of patient age.