Controlled-release oxycodone relieves neuropathic pain: a randomized controlled trial in painful diabetic neuropathy

Background: Painful neuropathy is one of the most common long-term complications of diabetes mellitus and often proves difficult to relieve. Methods: Patients with diabetic neuropathy with moderate or greater pain for at least 3 months, were evaluated for efficacy. safety and health-related quality of life (QOL) while receiving controlled-release (CR) oxycodone (OxyContin(R)) or active placebo. Patients underwent washout from all opioids 2-7 days before randomization to 10 mg CR oxycodone or active placebo (0.25 mg benztropine) q12h. The dose was increased, approximately weekly, to a maximum of 40 mg q12h CR oxycodone or I mg q12h benztropine, with crossover to the alternate treatment after a maximum of 4 weeks. Acetaminophen, 325-650 mg q4-6h prn was provided as rescue. Results: Thirty-six patients were evaluable for efficacy (21 men, 15 women, mean age 63.0 +/- 9.4 years). CR oxycodone resulted in significantly lower (P = 0.0001) mean daily pain (21.8 +/- 20.7 vs. 48.6 +/- 26.6 mm VAS), steady pain (23.5 +/- 23.0 vs. 47.6 +/- 30.7 mm VAS), brief pain (21.8 +/- 23.5 vs. 46.7 +/- 30.8 mm VAS), skin pain (14.3 +/- 20.4 vs. 43.2 +/- 31.3 mm VAS), and total pain and disability (16.8 +/- 15.6 vs. 25.2 +/- 16.7; P = 0.004). Scores from 6 of the 8 SF-36 domains and both summary scales, Standardized Physical Component (P = 0.0002) and Standardized Mental Component (P = 0.0338) were significantly better during CR oxycodone treatment. The number needed to treat to obtain one patient with at least 50% pain relief is 2.6 and clinical effectiveness scores favoured treatment with CR oxycodone over placebo (P = 0.0001). Conclusion: CR oxycodone is effective and safe for the management of painful diabetic neuropathy and improves QOL. (C) 2003 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.