Background and objective: Data from two similarly designed studies of tapentadol extended release (ER) for managing neuropathic pain associated with diabetic peripheral neuropathy (DPN; NCT00455520, NCT01041859) in adults were pooled for this analysis, allowing a detailed evaluation of efficacy in patient subgroups and secondary endpoints.
Methods: In each study, patients were titrated to their optimal dose of open-label tapentadol ER [100-250 mg twice daily (bid)] over 3 weeks. Patients with ≥1-point improvement in average pain intensity [11-point numerical rating scale (NRS)] were randomized (1:1) to receive placebo or tapentadol ER during a 12-week, double-blind maintenance period.
Results: Mean (standard deviation [SD]) changes in pain intensity from baseline to week 12 of maintenance in the placebo (n = 343) and tapentadol ER (n = 360) groups, respectively, were 1.28 (2.41) and 0.08 (1.87) [least squares mean difference (LSMD): -1.14 (95 % confidence interval [CI]: -1.435, -0.838); P < 0.001, in favour of tapentadol ER]. Significant between-group differences were also observed in changes from the start of the double-blind treatment period to the double-blind endpoint for the Short Form-36 physical functioning, role-physical, bodily pain, social functioning and role-emotional subscale and physical component summary scores, and the EuroQol 5-Dimension health status index (all P < 0.05, in favour of tapentadol ER). No clinically relevant differences were observed in the efficacy of tapentadol ER across patient subgroups divided by age, sex, race, opioid experience and pain intensity. Incidences of treatment-emergent adverse events were 56.0 % (192/343) with placebo and 74.7 % (269/360) with tapentadol ER during maintenance.
Conclusion: Results of this pooled analysis indicate that tapentadol ER was effective for managing DPN-related pain, and provided consistent analgesic efficacy across different patient subgroups.