[Measurement of amount of fentanyl remaining in used patches: investigation of clinical factors affecting the remaining amounts in 4 patients].
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 microg/h (2.5 mg FP); 44.9+/-5.1 cf. 50 microg/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.
Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda City, Japan. k.ymmt70@mc.pref.chiba.lg.jp
Kayo
K
Yamamoto
Masanori
M
Kojima
Hirofumi
H
Iguchi
Takafumi
T
Ohta
D000279:Administration, Cutaneous; D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000032:analysis* / Q000493:pharmacokinetics; D015992:Body Mass Index; D004304:Dosage Forms; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage* / Q000032:analysis* / Q000493:pharmacokinetics; D005334:Fever; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D012189:Retrospective Studies; D012869:Skin Absorption
D000701:Analgesics, Opioid; D004304:Dosage Forms; D005283:Fentanyl