Sweet potato starch microparticles as controlled drug release carriers: Preparation and in vitro drug release

The aim of this study was to investigate the in vitro drug release behavior of sweet potato starch (SPS) microparticles intended for controlled drug delivery applications. Diclofenac sodium (DS) was used as a model drug candidate in the present study. SPS microparticles were prepared using a spray-drying technique by varying the polymer concentration and drug loading. The mean particles size of drug-loaded spray-dried SPS microparticles was between 10.3 and 13.1 mu m. The mean particle size increased slightly with increase in the concentration of SPS. The mean particle size of spray-dried SPS microparticles increased from 10.3 to 13.1 pm when the concentration of SPS increased from 2 to 4% w/v. Under the current spray-drying conditions, the percentage yield of spray-dried SPS microparticles did not vary much among the various formulations and it was between 65.2 and 70.1%. The encapsulation efficiencies of SPS microparticles formulations was between 95.1-98.2%, suggesting good encapsulating ability of the SPS polymer by spary drying. Drug release from all the formulations of spray-dried SPS microparticles was controlled over period of 6h. The cumulative amount of drug release from the spray-dried SPS microparticles decreased with an increase in the concentration of SPS, while it increases as the drug loading is increased. Release of the drug from spray-dried SPS microparticles followed Fick's law of diffusion since a good correlation coefficient (R-2) was observed with the Higuchi plots (R-2 = 0.9928 to 0.9979).