title: Pharmacokinetics of fentanyl, alfentanil, and sufentanil in isoflurane-anesthetized cats.
abstract: The aim of this study was to compare the pharmacokinetics of fentanyl, alfentanil, and sufentanil in isoflurane-anesthetized cats. Six adult cats were used. Anesthesia was induced and maintained with isoflurane in oxygen. End-tidal isoflurane concentration was set at 2% and adjusted as required due to spontaneous movement. Fentanyl (10 μg/kg), alfentanil (100 μg/kg), or sufentanil (1 μg/kg) was administered intravenously as a bolus, on separate days. Blood samples were collected immediately before and for 8 h following drug administration. Plasma drug concentration was determined using liquid chromatography/mass spectrometry. Compartment models were fitted to concentration-time data. A 3-compartment model best fitted the concentration-time data for all drugs, except for 1 cat in the sufentanil group (excluded from analysis). The volume of the central compartment and the volume of distribution at steady-state (L/kg) [mean ± SEM (range)], the clearance (mL/min/kg) [harmonic mean ± pseudo-SD (range)], and the terminal half-life (min) [median (range)] were 0.25 ± 0.04 (0.09-0.34), 2.18 ± 0.16 (1.79-2.83), 18.6 ± 5.0 (15-29.8), and 151 (115-211) for fentanyl; 0.10 ± 0.01 (0.07-0.14), 0.89 ± 0.16 (0.68-1.83), 11.6 ± 2.6 (9.2-15.8), and 144 (118-501) for alfentanil; and 0.06 ± 0.01 (0.04-0.10), 0.77 ± 0.07 (0.63-0.99), 17.6 ± 4.3 (13.9-24.3), and 54 (46-76) for sufentanil. Differences in clearance and volume of distribution result in similar terminal half-lives for fentanyl and alfentanil, longer than for sufentanil.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Pypendop
authors.forename: R J
authors.initials: RJ
authors.lastname: Brosnan
authors.forename: C R
authors.initials: CR
authors.lastname: Majewski-Tiedeken
authors.forename: S D
authors.initials: SD
authors.lastname: Stanley
authors.forename: J E
authors.initials: JE
authors.lastname: Ilkiw
mesh_terms: D015760:Alfentanil / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000818:Animals; D019540:Area Under Curve; D002415:Cats / Q000097:blood* / Q000378:metabolism; D004347:Drug Interactions; D005283:Fentanyl / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D006207:Half-Life; D007530:Isoflurane; D017409:Sufentanil / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D015760:Alfentanil; D017409:Sufentanil; D007530:Isoflurane; D005283:Fentanyl