BALTIMORE, Md.—Tapentadol extended-release (ER), an investigational drug, was associated with better gastrointestinal tolerability in elderly patients with moderate-to-severe chronic pain, with fewer discontinuing the study due to treatment-emergent adverse events (TEAEs) than oxycodone controlled-release (CR), investigators concluded in a presentation during the 29th Annual Scientific Meeting of the American Pain Society.

David M. Biondi, DO, of Ortho-McNeil Janssen Scientific Affairs, Raritan, N.J., and colleagues conducted a post-hoc analysis of a phase III randomized, open-label, parallel-group, active-controlled, flexible-dose, one-year safety study, in tapentadol ER 100 to 250 mg bid demonstrated similar pain relief to oxycodone HCl CR 20 to 50 mg bid to evaluate incidences of and study discontinuations due to overall and gastrointestinal TEAEs in patients 65 years of age and older.

Kaplan-Meier plots estimated times to onset of and discontinuations due to constipation, nausea, or vomiting, and percentages of treatment days with these TEAEs were calculated. Of the 1117 patients in the safely analysis, 312 were elderly; 245 were treated with tapentadol ER and 67 with oxycodone CR.

Of those in the tapentadol ER group, 87.8% reported at least one TEAE compared with 94% in the oxycodone CR group; in addition, gastrointestinal TEAEs—mostly mild or moderate—were reported by 57.6% in the tapentadol ER group and 76.1% in the oxycodone group. Those receiving tapentadol ER had significantly lower percentages of treatment days with gastrointestinal TEAEs vs oxycodone CR: nausea (5.4% vs 14.0%), vomiting (2.4% vs 7.2%), or constipation (14.9% vs 31.6%) vs oxycodone CR; all P≤0.0021.

Any TEAE leading to study discontinuation occurred in 33.1% of those in the tapentadol ER group and 49.3% in the oxycodone CR group (P=0.0215); similarly, gastrointestinal TEAEs led to discontinuation in 14.3% in the tapentadol ER group and 31.3% of the oxycodone CR group (P=0.0021). Study withdrawal times for nausea, vomiting, or constipation were all significantly longer in those receiving tapentadol ER vs oxycodone (all P≤0.0099).