Preparation and Characterization of Chitosan-Based Spray-Dried Microparticles for the Delivery of Clindamycin Phosphate to Periodontal Pockets

Biodegradable spray-dried chitosan microparticles loaded with clindamycin phosphate (CDP) were formulated to deliver drugs locally into the periodontal pocket. The effects of spray dryer conditions, drug/polymer ratio, and added amounts of glutaraldehyde (GA) solution on the characterization of microparticles were investigated by determining process yield, encapsulation efficiency, particle size and size distribution, surface morphology, drug release, release kinetics, thermal analysis, and antimicrobial efficacy of formulations. Burst release was obtained for all formulations due to the water solubility of the drug, but the increased amount of chitosan decreased the drug release rates. Microparticles with a more wrinkled surface were obtained by increasing the amount of the drug. Incorporation efficiencies higher than 80% were obtained for all preparation conditions. The addition of GA caused higher viscosity of the chitosan solution, leading to larger particles with more spherical and smooth surface characteristics. However, the increased GA amount did not significantly influence the drug release. The data obtained from in vitro release experiments were best fitted to the Weibull and Higuchi models. The amorphous nature of the drug-loaded microparticles was detected by differential scanning calorimetric (DSC) thermographs. A delayed drug release of more than one week could be obtained by loading the drug into the chitosan microparticles. Antimicrobial efficacy studies reflected a positive drug release profile. These results indicate that spray-dried clindamycin-loaded microparticles with sustained antimicrobial efficacy appear to be a promising periodontal therapy for drug delivery into the periodontal pocket.