ABSTRACT
A double-blind, randomized, placebo-controlled trial was conducted to study the analgesic efficacy of the NMDA (N-methyl-D-aspartate) receptor antagonist memantine (1-amino-3,5-dimethyladamantane hydrochloride) in relieving postherpetic neuralgia (PHN). Memantine (or an identical-looking placebon=12/group) was administered at a dose of 10 mg/day for one week, and 20 mg/day for an additional 4 weeks. All patients were required to record their pain level twice daily during the entire study period, with the use of a 0-10 numerical pain scale (NPS). The McGill Pain Questionnaire (MPQ), spontaneous pain, and a series of mechanical and thermal stimuli-induced pain were measured with the use of a 0-100 visual analogue scale (VAS), on six office visits. Quantitative thermal testing (QTT) and routine blood tests were performed at the beginning and at the end of the study. Although reduction in spontaneous pain, mechanical and cold allodynia, mechanical hyperalgesia, and <