It was previously reported the safety and efficacy of oral tapentadol ER switched from other opioids for 8 weeks in subjects with moderate to severe cancer pain, who received opioid analgesics prior to study participation. All treatment emergent adverse events were evaluated in previous safety analysis. In this report, the incidence and timing of opioid specific adverse events related to tapentadol administration were analyzed and compared with those of morphine SR as a reference. Fifty subjects each was randomized to the tapentadol ER group and the morphine SR group. The incidences of major adverse events that are considered related to treatment in the tapentadol ER group and the morphine SR group were nausea (8.0%, 14.0%), vomiting (2.0%, 24.0%), constipation (8.0%, 20.0%), and somnolence (8.0%, 18.0%), the incidences of these events were lower in the tapentadol ER group. These results suggest that tapentadol ER is a orally opioid which has well safety profiles, and is a new option of cancer pain therapy.

The present multicenter, open-label study evaluated the efficacy and safety of tapentadol ER administered at 50 mg/day to 500 mg/day in opioid-naive and opioid-switching subjects with moderate to severe cancer pain. For opioid-naive subjects, the initial dose was tapentadol ER 50 mg/day. For opioid-switching subjects, the initial dose was determined depending on previously used opioid and was dose-adjusted for each subject. The study design consists of two parts of titration period and maintenance period to which a patient who achieves dose adjustment can proceed. The percentage of subjects achieving dose adjustment in the titration period was 93.3% for opioid-naive subjects and 80.6% for opioid-switching subjects. The percentage of subjects who maintained adequate analgesia throughout the maintenance period (primary endpoint) was 89.7% for opioid-naive subjects and 92.9% for opioid-switching subjects. The most frequent adverse events were were nausea, vomiting, somnolence, and constipation, all of which were commonly reported with the use of opioids. These findings showed that tapentadol ER was well tolerated in the dose range of 50 mg/day to 500 mg/day.