In our previous study, enrofloxacin-loaded docosanoic acid solid lipid nanoparticles (SLNs) could be effectively delivered to cells in vitro. In this study, its properties and exploitation as possible oral and intramuscular sustained release formulations for pigs were studied after being made into suspension. The re-dispersed time and sedimentation rate of the nanosuspension were 55 s and 1, respectively. It showed good stability when stored away from light and sustained release in pH = 7.4 PBS buffer. The suspension exhibited no irritation at the injection site and good palatability. Compared with commercial injection and soluble powder, the nanosuspension increased the bioavailability of enrofloxacin by 1.63 and 2.38 folds, and extended the mean residence time (MRT) of the drug from 11.27 and 12.33 to 37.76 and 35.15 h after intragastric and intramuscular administration, respectively. These results suggest that docosanoic acid SLN suspension (DAS) might be a promising oral and intramuscular sustained release formulation to enhance the pharmacological activity of enrofloxacin.
Keywords: Enrofloxacin; docosanoic acid-solid lipid nanoparticles; intramuscular formulation; oral formulation; suspension.