Chitosan and β-cyclodextrin microspheres as pulmonary sustained delivery systems

Chitosan and beta-cyclodextrin were used to prepare microspheres with theophylline for pulmonary delivery by spray drying method. The characteristics, mucociliotoxicity, permeation rate and drug release were studied. The drug entrapments of microspheres I, II and III were from 35.70% to 21.09% and 13.33%, while yields and encapsulation efficiencies were higher than 45% and about 90% respectively. The microspheres possessed low tap densities (0.34-0.48 g/cm(3)), appropriate diameters (3.35-3.94 mu m) and theoretical aerodynamics diameters (2.20-3.04 mu m). SEM images showed the microspheres were spherical with smooth or wrinkled surface surfaces. FT-IR demonstrated theophylline had formed hydrogen bonds with chitosan and beta-cyclodextrin. The microspheres could effectively reduce the ciliotoxicity and easy to penetrate the memberine. The in vitro release of the microspheres was related to the ratio of drug/polymer and microspheres It had a prolong release, providing the release of 72.00% in 12 h. The results suggestes that chitosan/beta-cyclodextrin microspheres II are a promising carrier as sustained release for pulmonary delivery.