Chitosan in Steroid Delivery: Formulation of Microspheres By Factorial Design and Evaluation of In-Vitro Release Parameters

The objective of this study is to evaluate the effect of formulation variables on the release characteristics of dexamethasone sodium phosphate (DSP) from chitosan microspheres. Chitosan microspheres containing DSP as the model drug were prepared by using high molecular weight chitosan with Brookfield viscosity 800.000. Microspheres were prepared by w/o emulsion formation followed by cross-linking process with the addition of gluteraldehyde as the cross-linking agent. The independent variables for factorial design studies were determined as cross-linking time and cross-linking agent amount with three different levels. The highest encapsulation efficiency was 86.96±1.18% for the batch prepared with 5ml gluteraldehyde for a cross-linking time of 1 hour. The in-vitro release parameters were determined by Weibull model and the t values for the microsphere formulations were compared with each other. Particle size distribution range was determined as 77.450 ± 0.07 and 136.787 ± 2.85 μm for all batches. As a result, chitosan microspheres which may maintain sustained release of DSP for approximately 10 hours were successfully formulated.