Tapentadol extended release: in adults with chronic pain.

The extended release (ER; as ascribed in the US) or prolonged release (PR; as ascribed in Europe) formulation (hereafter referred to as ER) of the oral analgesic tapentadol is believed to exert its analgesic effects via μ-opioid receptor agonistic and norepinephrine reuptake inhibitory activity. Direct conversion between tapentadol immediate release and tapentadol ER is permissible utilizing approximately equivalent total daily doses. For the most part, shorter-term (15 weeks) therapy with tapentadol ER 100-250 mg twice daily provided more effective pain relief and significantly improved functional and health status outcomes compared with placebo in four well designed studies in adult patients with moderate to severe chronic pain associated with knee osteoarthritis, the lower back or diabetic neuropathy. Moreover, longer-term (≤24 months) therapy with tapentadol ER provided sustained analgesic effects in two multinational tolerability studies in patients with moderate to severe chronic pain associated with knee or hip osteoarthritis or the lower back. The development of tolerance was not observed in clinical studies of tapentadol ER, with the mean total daily dose and the analgesic (mean pain intensity) scores remaining relatively stable over ≤24 months' therapy. Oral tapentadol ER therapy for up to 24 months was generally well tolerated, with the nature of treatment-emergent adverse events generally similar across the clinical studies.