Preclinical Evaluation of Rutin-Loaded Microparticles with an Enhanced Analgesic Effect

Abstract

This study aimed to develop and characterize microparticles containing rutin to improve the analgesic activity of the flavonoid. Rutin-loaded microparticles were produced with casein and pectin using the complex coacervation physicochemical method, resulting in an average particle size of 4.903 μm ± 4.421 (mean ± standard deviation), round shape, and irregular surfaces, and rutin crystals can be observed to be adsorbed on the outer surface of microparticles. The encapsulation efficiency was 76.9% as quantified by the antioxidant activity. In vivo, rutin-loaded microparticles showed greater inhibition of carrageenan-induced mechanical hyperalgesia (64%) than nonmicroencapsulated rutin (28%). The X-ray diffraction showed that rutin was dispersed in an amorphous matrix, and its crystallographic structure and crystal size did not exhibit changes. Differential scanning calorimetric studies confirmed that rutin was dispersed in the amorphous matrix within microparticles. The fact that rutin was dispersed in an amorphous matrix in the microparticles seemed to provide enhanced absorption, resulting in an improved analgesic efficacy compared with non-microencapsulated rutin. In conclusion, rutin-loaded microparticles were successfully produced, and they improved analgesic activity compared to non-microencapsulated rutin.