Formulation and optimization of chitosan-based amorphous fenbendazole microparticles through a design of experiment approach

Fenbendazole is a broad-spectrum anthelmintic used in veterinary medicine. It is a lipophilic benzimidazole derivative with low water solubility (<0.1 g/L) recently studied for repositioning in cancer treatment. These potential new uses highlight the need for new dosage forms. Thus, chitosan-crosslinked microparticles were prepared by spray drying, applying a Design of Experiments approach to optimize the composition of the microparticles, evaluating the type and mass of chitosan and crosslinking agent, alongside crosslinking reaction time. The recovered optimized microparticles were characterized by infrared spectroscopy, and changes in the drug crystalline phase were studied by differential scanning calorimetry and X-ray powder diffraction, further confirmed by wide-angle X-ray scattering. After encapsulation of fenbendazole in the chitosan-crosslinked matrix, the resulting microparticles had a particle size of 2.43 μm with a polydispersion index of 0.754 and a Zeta potential value of + 49.85 mV. In vitro dissolution showed that the optimized microparticles had an improved dissolution profile compared to the non-encapsulated drug. The analysis of the encapsulated drug in the solid state showed a remarkable reduction of its crystalline properties. In conclusion, these results demonstrate that fenbendazole encapsulation into an optimized chitosan-crosslinked matrix leads to better biopharmaceutical performance.