Electrosprayed 4-carboxybenzenesulfonamide-chitosan microspheres for acetazolamide delivery

4-Carboxybenzensulfonamide-chitosan (4-CBS-chitosan) microspheres were prepared by electrospraying with acetazolamide (ACZ) as a model drug. The obtained 4-CBS-chitosan microspheres with or without ACZ-loading were characterized by Fourier transform infrared spectroscopy, differential scanning colorimetry, scanning electron microscopy and particle size analyses. The crystalline form and the stability of ACZ in a basic solution was determined using X-ray single crystal analysis. 4-CBS-chitosan had 90% encapsulation efficiency for ACZ compared to 47% of encapsulation efficiency (EE) obtained from native chitosan, forming 3.1 μm diameter microspheres with a low polydispersity index (0.4). After an initial burst release (58% in 5 min), ACZ-loaded 4-CBS-chitosan gave a sustained release of ACZ (∼100% over 3 h) in simulated gastric fluid (0.1 N HCl; pH 1.2), which was better than that seen for the release from ACZ-loaded chitosan (44% over 1.5 h). Thus, 4-CBS-chitosan microspheres are a possible drug carrier in acidic conditions, such as at the gastric mucosal wall.