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<0.0434), and G-GR reduced sleep interference (-2.3 vs. -1.59; P<0.0001), although neither endpoint was considered statistically significant based on a stringent hierarchical statistical paradigm. Other secondary endpoints showed similar trends. The most common adverse events were dizziness (G-GR, 11.3% vs. placebo, 1.7 %) and somnolence (G-GR, 5.4% vs. placebo, 3.0%).


CONCLUSIONS
Once-daily G-GR 1800 mg was effective and well tolerated for the relief of pain in patients with postherpetic neuralgia.
Translational Pain Research, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. csang@partners.org
Christine N
CN
Sang
Rekha
R
Sathyanarayana
Michael
M
Sweeney
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000588:Amines / Q000008:administration & dosage / Q000627:therapeutic use*; D000700:Analgesics / Q000008:administration & dosage / Q000627:therapeutic use*; D003509:Cyclohexanecarboxylic Acids / Q000008:administration & dosage / Q000627:therapeutic use*; D003692:Delayed-Action Preparations; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D000077206:Gabapentin; D006801:Humans; D008297:Male; D008875:Middle Aged; D051474:Neuralgia, Postherpetic / Q000188:drug therapy*; D010147:Pain Measurement; D012720:Severity of Illness Index; D016896:Treatment Outcome; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000627:therapeutic use*
D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D003692:Delayed-Action Preparations; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin