Long-acting bulleyaconitine A microspheres via intra-articular delivery for multidimensional therapy of rheumatoid arthritis

Bulleyaconitine A (BLA) is a promising candidate for treating rheumatoid arthritis (RA) with diverse pharmacological activities, including anti-inflammatory, analgesic and bone repair. Herein, the long-acting bulleyaconitine A microspheres (BLA-MS) were developed to treat RA comprehensively by forming drug reservoirs in joint cavities. The BLA-MS were prepared by emulsion/solvent evaporation method. The particle size and distribution were assessed by SEM. The crystalline state was investigated by DSC and PXRD. The drug loading (DL), encapsulation efficiency (EE) and cumulative release in vitro were determined by HPLC. The DL and EE were 23.93 +/- 0.38 % and 95.73 +/- 1.56 % respectively, and the cumulative release was up to 69 days with a stable release curve. The pharmacodynamic results in collagen induced arthritis (CIA) rats showed a noticeable reduction in paw thickness (5.66 +/- 0.32 mm), and the decreasing expression level of PGE 2 , TNF- alpha and IL-6 which diminished the infiltration of inflammatory cells, thereby alleviating the progression of erosion and repairing the damaged bones (BV/TV (Bone Volume / Total Volume): 81.97 %, BS/BV (Bone Surface / Bone Volume): 6.08 mm-1 ). In conclusion, intra-articular injection of BLA-MS should have a promising application in the treatment of RA and may achieve clinical transformation in the future.