LAS VEGAS, NV — A study comparing tapentadol immediate-release and oxycodone immediate-release in moderate-to-severe, acute low back pain with radicular leg pain demonstrated comparable efficacy, with reduced gastrointestinal side effects seen with the tapentadol immediate-release arm, investigators reported during PAINWeek 2012.

The Phase 3 trial included patients aged ≥18 years, with acute lower back pain and radicular leg pain (intensity rated ≥5 on an 11-point numerical rating scale). Subjects were randomized to treatment with tapentadol immediate-release (50mg, 75mg, or 100mg) or oxycodone immediate-release (5mg, 10mg, or 15mg), administered every 4–6 hours as needed for 10 days. Pain intensity was noted twice daily.

The primary outcome was the sum of pain intensity differences over 120 hours, beginning at first dose of study agent. Tapentadol immediate-release was deemed non-inferior to oxycodone immediate-release when the upper limit of the 95% confidence interval for the least-squares mean difference was <120. Investigators assessed the sum of pain intensity differences over two, three, and ten days, in addition to 30% and 50% responder rates. Also, treatment-emergent adverse events were noted.

The least-squares mean of the sum of pain intensity differences over 120 hours was 264.6 for the tapentadol immediate-release group (287 patients) and 264.0 for the oxycodone immediate release group (298 subjects; 95% confidence interval -32.1, 30.9). Researchers found the sum of pain intensity differences at two, three, and ten days, as well as 30% and 50% responder rates at three, five, and ten days to be similar between treatment groups. Treatment-emergent adverse events of ≥10% frequency for tapentadol immediate-release (321 subjects) included: vomiting (15.9%), nausea (15.9%), and dizziness (11.8%); for oxycodone immediate-release (324 subjects), these included vomiting (24.7%), nausea (20.7%), and dizziness (10.5%). Tapentadol immediate-release also showed a better overall and GI tolerability profile than oxycodone immediate-release, particularly for vomiting and constipation.

Jim Xiang, MD, of Janssen Research & Development, Raritan, NJ, and colleagues concluded that tapentadol immediate-release was non-inferior to oxycodone-immediate release for relief of acute low back pain, with less gastrointestinal toxicity.