Tapentadol at medium to high doses in patients previously receiving strong opioids for the management of cancer pain.

OBJECTIVE: The aim of this study was to assess the efficacy and tolerability of tapentadol (TP) for a period of 4 weeks in patients who were already treated by opioids.
METHODS: A convenience sample of 30 patients was selected for a prospective observational cohort study. Cancer patients who were receiving at least 60 mg of oral morphine equivalents were selected. Patients discontinued their previous opioid analgesics before starting TP, in doses calculated according the previous opioid consumption (1:3.3 ratio with oral morphine equivalents). The subsequent doses were changed according to the patients' needs for a period of 4 weeks. Oral morphine was offered as a breakthrough pain medication. Pain and symptom intensity were recorded at weekly intervals. Distress score (DS) was calculated from the sum of symptom intensities. TP opioid escalation indexes (TPEI) for the study period were calculated.
RESULTS: Nineteen patients were male, and the mean age was 63.5 years (±11.5). The mean Karnofsky status was 62.9 (±10). The mean dose of oral morphine equivalents before switching to TP was 112 mg (±57) and the initial mean dose of TP was 343 mg (±150). Pain intensity significantly decreased. Tapentadol escalation index in percentage was 1.26 (TPEI% ± 2.6) and Tapentadol escalation index in mg was 2.76 (TPEImg ± 4.96). No significant relationships were found with primary tumor (TPEI%, p = 0.204; TPEImg, p = 0.180), pain mechanism (TPEI%, p = 0.863; TPEImg, p = 0.846), age (TPEI%, p = 0.882; TPEImg, p = 0.884), or gender (TPEI%, p = 0.287; TPEImg, p = 0.325). DS decreased, but non-significantly (p = 0.1). Ten patients did not complete the study period: five patients discontinued TP for uncontrolled pain, despite increasing doses of TP over 600 mg/day. Two patients discontinued TP for adverse effects and three patients dropped out, one patient for poor compliance and two patients for unrecorded reasons.
CONCLUSION: In our sample, TP used in doses of 350-450 mg/day was well tolerated and effective in opioid tolerant patients with cancer pain and could be considered as a flexible drug to be used for the management of moderate to severe cancer pain. Like most studies in patients with cancer pain, it was limited by its open-label, uncontrolled design, the number of patients lost in follow-up, and discontinuation of the treatment for several reasons. Further studies in a large number of patients should confirm these preliminary results.