title: Serum concentration of fentanyl during conversion from intravenous to transdermal administration to patients with chronic cancer pain.
abstract: BACKGROUND
  To the best of our knowledge, there have been no reports on the pharmacokinetics and pharmacodynamics during the conversion from continuous intravenous infusion (CII) to transdermal fentanyl administration. The primary objective of the present study was to clarify the pharmacokinetic characteristics during this conversion. A secondary objective was to identify an association between serum albumin and the absorption of fentanyl from the transdermal patch.
  
  
  METHODS
  A prospective study was conducted from February 2010 to August 2011 that enrolled 19 patients with chronic cancer pain. Patients were classified into 2 study groups according to body mass index and albumin level. All patients received the conversion from CII to transdermal fentanyl using a 2-step taper of CII over 6 hours. Comparisons of efficacy, toxicity, and serum fentanyl concentrations between study groups were analyzed at baseline, 3, 6, 9, 12, 15, 18, and 24 hours after initiation of the conversion.
  
  
  RESULTS
  The dose-adjusted serum fentanyl concentrations for all patients were significantly decreased at 15 to 24 hours after conversion compared with baseline, although pain intensity and the number of rescue events remained stable during the conversion. The dose-adjusted serum fentanyl concentrations at 9 to 24 hours were significantly reduced in the low albumin group compared with the normal albumin group (P<0.05).
  
  
  CONCLUSIONS
  Our study demonstrated that the dose-adjusted serum fentanyl concentrations remained relatively stable, and pain intensity and the number of rescue events remained stable during conversion. Hypoalbuminemia was strongly associated with poor absorption of transdermally administered fentanyl.
authors: Department of Clinical Oncology, Aichi Cancer Center Hospital, Aichi, Japan. excell@hkg.odn.ne.jp
authors: Motoo
authors: M
authors: Nomura
authors: Koichi
authors: K
authors: Inoue
authors: Shoko
authors: S
authors: Matsushita
authors: Daisuke
authors: D
authors: Takahari
authors: Chihiro
authors: C
authors: Kondoh
authors: Kohei
authors: K
authors: Shitara
authors: Takashi
authors: T
authors: Ura
authors: Kenji
authors: K
authors: Hayashi
authors: Hiroyuki
authors: H
authors: Kojima
authors: Minoru
authors: M
authors: Kamata
authors: Michiko
authors: M
authors: Tatematsu
authors: Renko
authors: R
authors: Hosoda
authors: Satoshi
authors: S
authors: Sawada
authors: Hisao
authors: H
authors: Oka
authors: Kei
authors: K
authors: Muro
mesh_terms: D000279:Administration, Cutaneous; D061605:Administration, Intravenous; D000328:Adult; D000368:Aged; D000418:Albumins / Q000378:metabolism; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000097:blood*; D015992:Body Mass Index; D059350:Chronic Pain / Q000097:blood* / Q000188:drug therapy*; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage* / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D000418:Albumins; D000701:Analgesics, Opioid; D005283:Fentanyl