Preparation and Pharmacokinetics of an Injectable Thermosensitive Hydrogel of Diminazene Aceturate

An injectable thermosensitive hydrogel of diminazene aceturate was prepared and its release properties were evaluated. Chitosan, glycerol 2-phosphate disodium salt hydrate (β-GP) and PEG-600 consisted of blank hydrogel which showed a sol-gel phase transition at 37 °C. However, while diminazene aceturate aqueous solution was added into blank hydrogel, suspension was formed due to plus-to-minus charge interactions. The addition of PEG-600 can decrease transition time of hydrogel suspension. The mean particle size was 2.762 ± 1.058 μm and ζ potential was 5.407 ± 1.280 mV. The in vitro release experiments demonstrated drug release from hydrogel was mainly controlled by Fickian diffusion with first-order kinetics, and skeleton erosion should also play a partial role owing to the biodegradability of chitosan. Pharmacokinetics of drug-suspended hydrogel and its aqueous solution indicated hydrogel can significantly reduce drug elimination, increase mean residence time and improve bioavailability of diminazene aceturate after subcutaneous administration in rabbits. Therefore, it would be an alternative sustained-release preparation for the prevention or treatment of chronic hemozoon diseases in veterinary practice.