Pharmacokinetics of fentanyl, alfentanil, and sufentanil in isoflurane-anesthetized cats.

摘要

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 micro g/kg), alfentanil (100 micro g/kg), or sufentanil (1 micro g/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+or-SEM (range)], the clearance (mL/min/kg) [harmonic mean+or-pseudo-SD (range)], and the terminal half-life (min) [median (range)] were 0.25+or-0.04 (0.09-0.34), 2.18+or-0.16 (1.79-2.83), 18.6+or-5.0 (15-29.8), and 151 (115-211) for fentanyl; 0.10+or-0.01 (0.07-0.14), 0.89+or-0.16 (0.68-1.83), 11.6+or-2.6 (9.2-15.8), and 144 (118-501) for alfentanil; and 0.06+or-0.01 (0.04-0.10), 0.77+or-0.07 (0.63-0.99), 17.6+or-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.