Tapentadol IR Noninferior to Oxycodone IR with More Favorable GI Profile

PALM SPRINGS, CA — In a Phase 3 study of tapentadol immediate-release (IR) versus oxycodone IR for moderate-to-severe, acute low-back pain with radicular leg pain, tapentadol IR was noninferior to oxycodone IR, with a more favorable gastrointestinal-tolerability profile. Results of the study were presented at the 2012 American Academy of Pain Medicine Annual Meeting by Charles Oh, MD, and colleagues from Janssen Scientific Affairs, Raritan, NJ.

Dr. Oh et al. sought to evaluate the efficacy and tolerability of tapentadol IR vs. oxycodone IR in adult patients ≥18 years old with acute low-back pain (intensity ≥5; 11-point numerical rating scale[NRS]) with radicular leg pain (on more than one side), with onset ≤30 days before screening. Clinical presentation was consistent with Category 3, Category 4, or Category 6 of the Quebec Task Force Classification for Spinal Disorders (QTFC) algorithm.

This multicenter, parallel-group study was comprised of a 1-day screening/randomization phase and a ≤10-day, double-blind treatment phase. Patients were divided into two groups: those meeting criteria for QTFC Category 3 into Group 1 and those meeting criteria for QTFC Category 4 and 6 into Group 2. Within each group, patients were randomized 1:1 to receive tapentadol IR 50mg, 75mg, or 100mg or oxycodone HCl IR 5mg, 10mg, or 15mg. Dosing was flexible, and treatment could be administered every 4–6 hours as needed for up to 10 days. No more than six doses of tapentadol IR 100mg or oxycodone HCl IR 15mg could be administered per day. Pain intensity was recorded in the morning and evening daily using the 11-point NRS.

The primary efficacy endpoint was the sum of pain-intensity differences (SPID) over 120 hours (SPID120; starting at first study dose). Tapentadol IR was considered noninferior to oxycodone IR when the upper bound of the 95% CI for the least-squares mean difference was <120. Researchers evaluated SPID over two, three, and ten days as well as the 30% and 50% responder rates. Investigators also documented treatment-emergent adverse events (TEAEs).

The efficacy (modified intent-to-treat [mITT]) population (Group 1 [n=290], Group 2 [n=295]) included all randomized patients who received ≥1 dose of medication and had a baseline pain intensity score ≥5. Patient demographic and baseline characteristics were similar between groups.

At the study's conclusion, least-squares mean of SPID120 was 264.6 for tapentadol IR (n=287) and 264.0 for oxycodone IR (n=298; 95% CI −32.1, 30.9). SPID at two, three, and ten days, and 30% and 50% responder rates at three, five, and ten days, were similar between treatment groups. TEAEs (≥10%) with tapentadol IR (n=321) vs. oxycodone IR (n=324) included vomiting (15.9% vs. 24.7%), nausea (15.9% vs. 20.7%), and dizziness (11.8% vs. 10.5%). Treatment discontinuation was primarily due to adverse events for both tapentadol IR and oxycodone IR groups (6.5% vs. 7.1%, respectively). Additionally, time to treatment discontinuation for any reason was significantly longer with tapentadol IR (mean treatment duration was 9.4 days vs. 9.1 days; P=0.0454).