To compare oxymorphone extended release (ER) and placebo on indices of pain, function, and safety in patients with chronic osteoarthritis (OA) pain.
In this multicenter, double-blind, placebo- and active-controlled, parallel-group, dose-ranging study, patients were randomized to oxymorphone ER 20 mg (N = 121), oxymorphone ER 40 mg (N = 121), oxycodone controlled release 20 mg (N = 125), or placebo (N = 124) every 12 hours. The primary efficacy end point was change in arthritis pain intensity (visual analog scale, 0-100) from baseline to week 3 for the oxymorphone ER 40 mg group versus placebo.
The primary end point was achieved: the week 3 oxymorphone ER least squares mean difference (LSMD) from placebo was -9.0 (95% confidence interval [CI]: -16.2 to -1.8; P = 0.015). Secondary efficacy analysis showed similar improvements at week 4 (LSMD from placebo, -10.3 [95% CI: -17.7 to -2.8]; P = 0.007) and with oxymorphone ER 20 mg at week 3 (LSMD from placebo, -7.7 [95% CI: -15.0 to -0.4]; P = 0.039) and week 4 (LSMD from placebo, -7.5 [95% CI: -15.0 to 0.0]; P = 0.050). Weeks 3 and 4 pain intensity decreased by approximately 30-40%. Oxymorphone ER 20 and 40 mg improved from baseline on the Western Ontario and McMaster Universities Osteoarthritis Composite Index and pain and physical function subscales at week 4. Adverse events in all opioid groups included mild to moderate nausea, constipation, and somnolence.
In this short-term study, oxymorphone ER was superior to placebo for relieving pain and improving function in patients with moderate to severe chronic OA pain, and is an alternative to other sustained-release opioids.