使用済みフェンタニルパッチの残存薬物量測定：4症例における残存量に影響を及ぼす臨床因子の検討

抄録

  Although fentanyl patches (FP) designed to sustain plasma fentanyl concentrations for 3 days are used in many patients for continuous relief of moderate to severe cancer pain, there are some cases in which effective pain relief is sustained less than for 3 days, and in which plasma fentanyl concentrations rapidly decrease at the third day after the application. In this study, we measured the amount of fentanyl remaining in FP after continuous 3-days use to clarify some clinical factors that can influence the remaining amounts in 4 patients. Average estimated fentanyl-dermal transfer rates of the collected 41 patches calculated from their remaining amounts were less than nominal rates (21.2±3.4 cf. 25 μg/h (2.5 mg FP); 44.9±5.1 cf. 50 μg/h (5 mg FP)). Intra-individual variability was also observed (CV: 6.6-14.3% (2.5 mg FP), 3.9-13.3% (5 mg FP)). The present study suggests that the estimated fentanyl-dermal transfer rates are affected by fever, patients' body mass index and application sites. Although further study is necessary to elucidate factors that can influence the variability in transdermal fentanyl absorption, the approach in this study would contribute to improving appropriate usage of FP.