Hydroxypropyl Chitosan Bearing β ‐Cyclodextrin Cavities: Synthesis and Slow Release of its Inclusion Complex with a Model Hydrophobic Drug

Summary: Hydroxypropyl chitosan‐ graft ‐carboxymethyl β ‐cyclodextrin (HPCH‐ g ‐CM β ‐CD) was synthesized by grafting CM β ‐CD onto HPCH using water soluble 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) as the condensing agent. Due to the presence of hydrophobic β ‐CD rings onto the HPCH backbone, this polymer can be used as a matrix for controlled drug release. The adsorption of a hydrophobic model drug, ketoprofen, by HPCH‐ g ‐CM β ‐CD microparticles (using tripolyphosphate as an ionic crosslinking agent) fitted well in the Langmuir isotherm equation. The drug dissolution profile showed that HPCH‐ g ‐CM β ‐CD microparticles provided a slower release of the entrapped ketoprofen than chitosan, and the release behavior was influenced by the pH value of the medium. These results suggest that β ‐CD grafted with chitosan derivatives may become a potential biodegradable delivery system to control the release of hydrophobic drugs with pH‐responsive capability.The structure and drug release profiles of HPCH‐ g ‐CM β ‐CD.