title: Once-daily gastroretentive gabapentin for postherpetic neuralgia: integrated efficacy, time to onset of pain relief and safety analyses of data from two phase 3, multicenter, randomized, double-blind, placebo-controlled studies.
abstract: BACKGROUND
  Treatment options for postherpetic neuralgia (PHN), a complication of herpes zoster, are commonly unsatisfactory and associated with adverse events.
  
  
  OBJECTIVE
  To evaluate the efficacy, onset of pain relief, and safety of gastroretentive gabapentin (G-GR) in patients with PHN.
  
  
  METHODS
  In two placebo-controlled studies, 357 patients with PHN were randomized to 1800mg G-GR and 364 patients were randomized to placebo taken with the evening meal. Patients underwent a two week titration, eight weeks of stable dosing, and one week of tapering. Efficacy assessments included change in average daily pain (ADP) score from baseline to Week 10, time to onset of pain relief, the proportion of patients feeling improved using the Patient Global Impression of Change, and the proportion of responders (≥30% pain reduction).
  
  
  RESULTS
  At Week 10, patients randomized to G-GR reported greater reductions in ADP score compared with placebo (-37.0% vs. -29.1; P=0.0025). More G-GR patients felt improved compared with placebo (44% vs. 33%; P=0.003) and responded to treatment (54% vs. 41%; P=0.001). As early as Day 2, greater pain reductions were observed for the G-GR group compared with the placebo group (-6.6% vs. -1.6%; P=0.0017). The median time to a one point or greater reduction in ADP score was four days for G-GR and six days for placebo (P<0.0001). The most frequently reported adverse events were dizziness (G-GR, 11%; placebo, 2%) and somnolence (G-GR, 5%; placebo, 3%).
  
  
  CONCLUSIONS
  PHN pain reduction after G-GR treatment can be observed as early as the second day of dosing and continues for at least 10 weeks.
authors.affiliation: Center for Clinical Research, Winston-Salem, North Carolina, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Rauck
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Irving
authors.forename: Mark S
authors.initials: MS
authors.lastname: Wallace
authors.forename: Geertrui F
authors.initials: GF
authors.lastname: Vanhove
authors.forename: Michael
authors.initials: M
authors.lastname: Sweeney
mesh_terms: D000588:Amines / Q000008:administration & dosage*; D000700:Analgesics / Q000008:administration & dosage*; D015984:Causality; D015897:Comorbidity; D003509:Cyclohexanecarboxylic Acids / Q000008:administration & dosage*; D006970:Disorders of Excessive Somnolence / Q000453:epidemiology*; D004244:Dizziness / Q000453:epidemiology*; D004304:Dosage Forms; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004339:Drug Compounding; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D000077206:Gabapentin; D006801:Humans; D008297:Male; D051474:Neuralgia, Postherpetic / Q000188:drug therapy*; D010147:Pain Measurement / Q000187:drug effects* / Q000706:statistics & numerical data*; D015990:Placebo Effect; D015995:Prevalence; D012307:Risk Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage*
chemical_list: D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D004304:Dosage Forms; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin