摘要Despite advances in treatment of chronic arthritis,there is still a strong need for the development of long-acting formulations that can enable local and sustained drug release at the inflamed tissues.In this work,we fabricated microcrystals of an acid-sensitive stearoxyl-ketal-dexamethasone prodrug for treatment of arthritis.Microcrystals of the prodrug with two sizes were successfully engineered and showed pH-dependent hydrolysis kinetics in vitro.In a collagen-induced arthritis rat model,we evaluated the influence of particle size and injection dose on anti-inflammatory effect after intra-articular injection.Such prodrug demonstrated long-acting anti-arthritis effects with good safety.Our results indicate ketal-based prodrugs are promising for the development of long-acting injectables and may stimulate the development of new treatments for chronic diseases.