Divalproex sodium in the management of post-herpetic neuralgia: a randomized double-blind placebo-controlled study

QJM. 2005 Jan;98(1):29-34. doi: 10.1093/qjmed/hci005.

Abstract

Background: Post-herpetic neuralgia is difficult to treat. Divalproex sodium (valproic acid and sodium valproate in molar ratio 1:1) has been used successfully in the management of various painful neuropathies.

Aim: To study the effectiveness and safety of divalproex sodium in the management of post-herpetic neuralgia.

Design: Randomized double-blind placebo-controlled trial.

Methods: We enrolled 48 consecutively attending out-patients with post-herpetic neuralgia, out of whom three were excluded (two had insufficient pain, one withdrew consent). Quantification of pain was by Short Form-McGill pain questionnaire (SF-MPQ), visual analogue scale (VAS), present pain intensity score (PPI) and 11 point Likert scale (11 PLS) at the beginning of the study, after 2 weeks, 4 weeks and at the end of the study (8 weeks). We also assessed patients' global impression of change by questionnaire at the end of the study.

Results: After 8 weeks treatment with 1000 mg/day divalproex sodium, there was significant reduction in pain: SF-MPQ, 20.47 +/- 2.29 to 11.90 +/- 6.52 (p < 0.0001); PPI 4.0 +/- 0.52 to 1.95 +/- 1.29 (p < 0.0001); VAS 70.17 +/- 9.21 to 31.27 +/- 29.74 (p < 0.0001) and 11 PLS 6.97 +/- 0.73 to 3.63 +/- 2.34 (p < 0.0001) in comparison to placebo (means +/- SEM). The 'global impression of change' questionnaire showed much or moderate improvement in pain in 58.2% of patients receiving divalproex vs. 14.8% of those receiving placebo. The drug was well tolerated by all patients, except one who developed severe vertigo after 10 days of treatment.

Discussion: Divalproex sodium provides significant pain relief in patients of post-herpetic neuralgia, with very little incidence of adverse reactions. These data provide a basis for longer trials in a larger group of patients.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Double-Blind Method
  • Female
  • GABA Agents / adverse effects
  • GABA Agents / therapeutic use*
  • Herpes Zoster / complications*
  • Humans
  • Male
  • Middle Aged
  • Neuralgia / drug therapy*
  • Neuralgia / virology
  • Pain Measurement / methods
  • Patient Satisfaction
  • Treatment Outcome
  • Valproic Acid / adverse effects
  • Valproic Acid / therapeutic use*

Substances

  • GABA Agents
  • Valproic Acid