To compare two microspheres of chitosan/β-cyclodextrin and carboxymethyl chitosan/β-cyclodextrin loaded theophylline as pulmonary sustained drug delivery carriers,the characteristics and ciliotoxicity were studied.The drug loadings of chitosan/ β-cyclodextrin and carboxymethyl chitosan/β-cyclodextrin microspheres were 21.09% and 21.42%,and the encapsulation efficiencies were 91.40% and 92.80%.The distributions of 50%(d0.5) of chitosan/β-cyclodextrin and carboxymethyl chitosan/β-cyclodextrin microspheres were 4.89 and 5.83 μm,respectively.Both microspheres showed spherical shape with smooth or wrinkled surfaces.FT-IR of chitosan/β-cyclodextrin microspheres demonstrated that theophylline had formed hydrogen bonds with chitosan and β-cyclodextrin,while for the carboxymethyl chitosan/β-cyclodextrin microspheres theophylline had interaction with carboxymethyl chitosan.The moisture absorption showed that an equilibrium was reached within 24 h.The two microspheres possessed better adaptability.In vitro release of theophylline from chitosan/ β-cyclodextrin microspheres was slower than that from carboxymethyl chitosan/β-cyclodextrin microspheres at pH 6.8.
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