Preparation and <i>In Vitro</i> Activity Study of Grapiprant Nano-Particles by Intravenous Injection

Grapiprant (Gra), a specific antagonist of prostaglandin E2 receptors, is clinically utilized for the treatment of canine osteoarthritis (OA). As a hydrophobic small molecule drug, it is rapidly cleared from synovial fluid following intra-articular injection, which limits its anti-inflammatory therapeutic effect over extended periods. In this study, poly(lactic-co-glycolic acid) (PLGA), chitosan (CS) and hyaluronic acid (HA) were employed to formulate Gra-loaded HA/CS/PLGA@Gra nanoparticles (NPs). The HA/CS/PLGA@Gra NPs exhibited a hydrodynamic particle size of approximately 274.2[Formula: see text]nm, a narrow size distribution, a negative zeta potential of −21.5[Formula: see text]mV, and a smooth surface morphology. In vitro drug release experiments demonstrated that HA/CS/PLGA@Gra displayed sustained-release properties under both pH 7.4 and pH 5.0 conditions. In RAW264.7 macrophages, the cellular uptake of HA/CS/PLGA NPs was significantly enhanced, and they exhibited high targeting efficiency for M1-type RAW264.7 macrophages stimulated by lipopolysaccharide. Furthermore, HA/CS/PLGA@Gra can inhibit inflammation by eliminating reactive oxygen species (ROS) within cells. The hemolysis test indicated that the hemolysis rate of this compound is below 5% when the concentration of the primary drug, Grapiprant, ranges from 6.25 to 50[Formula: see text][Formula: see text]g/mL. Collectively, HA/CS/PLGA@Gra holds promise as a long-acting NPs for the treatment of –(OA) in animals.