EFFICACY OF OXYCODONE IN NEUROPATHIC PAIN - A RANDOMIZED TRIAL IN POSTHERPETIC NEURALGIA

Objective: Although opioid analgesics are used in the management of ne uropathic pain syndromes, evidence of their efficacy remains to be est ablished. We evaluated the clinical efficacy and safety of oxycodone i n neuropathic pain using postherpetic neuralgia as a model. Methods: P atients with postherpetic neuralgia of at least moderate intensity wer e randomized to controlled-release oxycodone 10 mg or placebo every 12 hours, each for 4 weeks, using a double-blind, crossover design. The dose was increased weekly up to a possible maximum of 30 mg every 12 h ours. Pain intensity and pain relief were assessed daily, and steady ( ongoing) pain, brief (paroxysmal) pain, skin pain (allodynia), and pai n relief were recorded at weekly visits. Clinical effectiveness, disab ility, and treatment preference were also assessed. Results: Fifty pat ients were enrolled and 38 completed the study (16 men, 22 women, age 70 +/-11 years, onset of postherpetic neuralgia 31 +/- 29 months, dura tion of pain 18 +/- 5 hours per day). The oxycodone dose during the fi nal week was 45 +/- 17 mg per day. Compared with placebo, oxycodone re sulted in pain relief (2.9 +/- 1.2 versus 1.8 +/- 1.1, p = 0.0001) and reductions in steady pain (34 +/- 26 versus 55 +/- 27 mm, p = 0.0001) , allodynia (32 +/- 26 versus 50 +/- 30 mm, p = 0.0004), and paroxysma l spontaneous pain (22 +/- 24 versus 42 +/- 32 mm, p = 0.0001). Global effectiveness, disability, and masked patient preference all showed s uperior scores with oxycodone relative to placebo (1.8 +/- 1.1 versus 0.7 +/- 1.0, p = 0.0001; 0.3 +/- 0.8 versus 0.7 +/- 1.0, p = 0.041; 67 % versus 11%, p = 0.001, respectively). Conclusions: Controlled-releas e oxycodone is an effective analgesic for the management of steady pai n, paroxysmal spontaneous pain, and allodynia, which frequently charac terize postherpetic neuralgia.