Meloxicam (MLX) is a commonly used drug in the clinical treatment of osteoarthritis, but it is associated with gastrointestinal adverse reactions. Therefore, in this study, we developed a sustained-release microsphere formulation of MLX for topical administration of knee joint. The MLX-loaded PLGA microspheres (MLX-MS) were prepared by emulsion solvent evaporation method with optimization of formulation using orthogonal experimental design. Physicochemical characterization results show MLX-MS were spherical with a smooth surface, the particle size was about 100 μm, drug loading was 30%, and encapsulation efficiency was 76.8%. In addition, the in vivo pharmacokinetics, tissue distribution, and pharmacodynamics were evaluated in rats by intra-articular administration of MLX. The microspheres showed a typical long-term sustained release pattern with a low initial burst release. In contrast to oral administration, local injection of MLX-MS produced a much higher value of elimination half-life time(T1/2) and peak time (Tmax) in plasma, while the intestinal drug distribution was significantly decreased. MLX-MS could also cause a greater reduction in the body level of IL-6 and TNF-α, which was positively correlated with R2=0.981. A good linear relationship (R2 = 0.9945) between the in vitro and in vivo drug release from MLX-MS could be observed, bivariate correlation analysis. All the findings demonstrated that local administration of MLX-MS can prolong the action time of MLX and reduce side effects, thus would be a promising preparation for the treatment of arthritis.
Keywords: Meloxicam; PLGA blends; anti-inflammatory; microsphere; osteoarthritis; topical administration.