Cats are deficient in the metabolism of propofol and the data on the pharmacokinetics in this species are scarce. The aim of this study was to determine the pharmacokinetic profile of continuous infusion of propofol in lipid emulsion and compare with the nanoemulsion formulation, in cats. Domestic cats, short hair, adults, male, castrated, weighting 4.2±0.8kg in a randomized and self control trial were used. The animals received 10mg kg-1 of 1% propofol in lipid emulsion or nanoemulsion for 30 seconds and immediately after that, a continuous rate infusion of 0.3mg kg-1 min-1 of the same formulation was administered for 60 minutes. After 15 days the cats received the same treatment with the opposite formulation. Samples of 3mL of venous blood were collected by a central venous catheter inserted in the jugular vein at 0 (baseline), 2, 5, 10, 15, 30, and 60 minutes of infusion and at 5, 10, 15, 30, 60, 90, 120, 180, 240, 360, 600 and 1440 minutes after the end of the infusion. The pharmacokinetic parameters were determined from the decay curve of plasma concentration versus time at the end of the infusion. Statistical analysis was performed using RM-ANOVA with subsequent paired t-test between groups. There was no difference between the formulations with respect to all parameters. The volumes of distribution were high with Vdss of 23.23±12.30 liters kg-1 for the nanoemulsion and 18.12±8.54 liters kg-1 for lipid emulsion. The Cls were low with a Cl central to 22.20±10.83mL kg-1 min-1 for the nanoemulsion and 23.42±13.50mL kg-1 min-1 for lipid emulsion. The conclusion is that the pharmacokinetics of propofol in cats after infusion is characterized by a broad tissue distribution and a slow elimination, with possible cumulative effect. The formulation nanoemulsion has pharmacokinetic properties similar to the lipid emulsion.
total intravenous anesthesia; formulation; nanotechnology; continuous infusion; lipid emulsion
