Study Drug Proves Effective in Relieving Diabetic Peripheral Neuropathy

Phase III study results show that patients suffering from diabetic peripheral neuropathy treated with tapentadol ER reported significant improvement in their pain.

With the recent news from the US Centers for Disease Control and Prevention (CDC) that an estimated 26 million Americans have diabetes (including 8.3% of Americans of all ages, and 11.3% of adults aged 20 and older), there has also been increased scrutiny on the complications and comorbidities associated with diabetes, including diabetic peripheral neuropathy (DPN).

According to this news release, which summarizes the results of a study that investigated the use of tapentadol ER for the relief of moderate to severe chronic pain associated with DPN, 60-70% of people with diabetes have some form of neuropathy, with DPN the most common, affecting up to 20% of patients with diabetes. The study, “Safety and Efficacy of Tapentadol ER in Patients with Painful Diabetic Peripheral Neuropathy,” was published in the January 2011 issue of Current Medical Research and Opinion.

The study enrolled nearly 600 patients who at had at least a three-month history of opioid and/or non-opioid analgesic use for DPN, were dissatisfied with their current treatment, and who reported an average pain intensity score of at least 5 on an 11-point numerical rating scale (NRS). The study included a three-week, open-label phase, during which “all patients were titrated to their individually optimal tapentadol ER dose (100-250 mg two times per day),” followed by a 12-week, double-blind maintenance phase, during which the 395 patients who reported at least a one-point reduction in pain intensity “were randomized either to continue taking tapentadol ER (at their optimal dose) or to receive placebo.”

The primary endpoint for the study was the change in average pain intensity from randomization, determined by twice-daily NRS measurements. At baseline, nearly 80% of patients (79.4%) reported severe pain (greater than or equal to 6 on the 11-point NRS) with a mean pain intensity of 7.3. Mean pain intensity was reduced to 3.5 by the end of the open-label phase. Among patients who qualified for the maintenance phase of the study, patients receiving placebo reported an average change in pain intensity of 1.4, while the tapentadol ER group reported maintenance of their pain relief (average change in pain intensity of 0.0 on the NRS).

A total of 60.5% (356/588) of patients reported at least a 30% improvement in pain intensity from baseline to the end of the open-label titration phase; 53.6% of the patients who were randomized to tapentadol ER in the maintenance phase reported at least a 30% improvement in pain intensity. Analyzing the effect of treatment using patient's global impression of change revealed that 64.4% of patients receiving tapentadol ER and 38.4% of patients receiving placebo reported that their overall status was “very much improved” or “much improved” at the end of the maintenance phase.

Investigators reported that the most common treatment-emergent adverse events (TEAEs) during the open-label phase were nausea (21.4%), dizziness (15.8%), somnolence (15.1%), constipation (10.7%), vomiting (8.0%), headache (7.8%), fatigue (7.0%) and pruritus (6.6%). The most common TEAEs experienced by patients who receievd tapentadol ER during the maintenance phase included nausea (13.8%), anxiety (9.2%), diarrhea (8.2%), and dizziness (7.7%).

The authors of the study concluded that compared with placebo, “tapentadol ER 100—250 mg bid provided a statistically significant difference in the maintenance of a clinically important improvement in pain, and was well-tolerated by patients with painful DPN.”