[Clinical Effects of Opioid Switching to Tapentadol - Retrospective Analysis of Efficacy and Adverse Effects].

: The objective of our study was to evaluate the efficacy and adverse effects of opioid switching to tapentadol(TP). It was a retrospective survey carried out at the Kitasato University Hospital outpatient clinic between September 2014 and May 2016. We evaluated pain intensity using the visual analogue scale and the occurrence of adverse effects before switching, at the first evaluation after switching, and during the steady state of TP administration. We included 10 patients; of these, 3 patients discontinued TP owing to uncontrolled pain. The conversion ratio of the previously administered opioids to TP was 1.17 at the time of the first evaluation after switching and 1.42 during the steady state. The mean(±SD)pain intensity was 4.2±2.2 before opioid switching and 4.6±2.2 at the time of the first evaluation after switching. The mean(±SD)pain intensity in the 7 patients excluding the 3 patients who discontinued TP was 4.3±2.0 before opioid switching and 2.7±1.9 during the steady state. Somnolence improved in 5 patients and constipation improved in 2 patients when a stable dose was achieved. Opioid switching to TP was appropriately accomplished using the conversion ratio. Furthermore, pain, sleepiness, and constipation improved following successful titration. These data suggest that TP can be useful in the treatment of cancer pain, in addition to the currently used opioid preparations.