Tolerability and safety of gastroretentive once-daily gabapentin tablets for the treatment of postherpetic neuralgia

Abstract

Objective

An immediate-release formulation of gabapentin is approved for treatment of postherpetic neuralgia (PHN). This formulation, however, requires multiple daily dosing, usually three times per day, and is associated with a high incidence of somnolence and dizziness. We assessed the tolerability and safety of a once-daily gastroretentive formulation of gabapentin (G-GR) in phase 3 clinical trials in patients with PHN.

Research design and methods

Data were pooled from two placebo-controlled studies involving 723 patients (G-GR 1800 mg, n = 359; placebo, n = 364). Patients (43% male, mean age 66 years) with PHN pain >4 (0–10 scale) for ≥3 months were enrolled. Summary statistics for the incidence of treatment-emergent adverse events (AEs) were performed. Laboratory parameters and vital signs were assessed.

Results

Treatment-emergent AEs were reported in 48% of patients (G-GR, 54%; placebo, 42%) and led to discontinuation in 8% of patients (G-GR, 10%; placebo, 7%). The most frequent (≥3% in any group) AEs were dizziness (G-GR, 11%; placebo, 2%), somnolence (G-GR, 5%; placebo, 3%), headache (G-GR, 4%; placebo, 4%), peripheral edema (G-GR, 4%; placebo, <1%), and diarrhea (G-GR, 3%; placebo, 3%). Serious AEs were reported in seven patients in the G-GR group (2%) and ten patients in the placebo group (3%). There were two deaths, both in the placebo group. No serious AEs were considered related to treatment. Mean values for laboratory parameters and vital signs at the end of each study were similar between groups.

Conclusion

G-GR was safe and well tolerated for the treatment of PHN.

Keywords:

• gabapentin
• postherpetic neuralgia
• adverse events
• dizziness
• somnolence
• gastroretentive

Acknowledgments

Editorial support was provided by Ed Parr, PhD, CMPP, of Envision Scientific Solutions, Southport, CT, and funded by Abbott. Medical writing support was provided by Stephanie Kareht, PhD, at Depomed. The authors thank Eric Sondag, PhD, formerly of Abbott, and Geertrui Vanhove, MD, PhD, from Depomed for their suggestions and advice during development of the manuscript, and Stephanie Kareht, PhD for assistance with the production of figures.

Disclosure

These analyses were sponsored by Depomed. Gordon Irving has previously received an honorarium from Depomed for participation on an advisory board. Michael Sweeney is an employee of Depomed.