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

<jats:title>Abstract</jats:title><jats:p><jats:bold>Summary:</jats:bold> Hydroxypropyl chitosan‐<jats:italic>graft</jats:italic>‐carboxymethyl <jats:italic>β</jats:italic>‐cyclodextrin (HPCH‐<jats:italic>g</jats:italic>‐CM <jats:italic>β</jats:italic>‐CD) was synthesized by grafting CM <jats:italic>β</jats:italic>‐CD onto HPCH using water soluble 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) as the condensing agent. Due to the presence of hydrophobic <jats:italic>β</jats:italic>‐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‐<jats:italic>g</jats:italic>‐CM <jats:italic>β</jats:italic>‐CD microparticles (using tripolyphosphate as an ionic crosslinking agent) fitted well in the Langmuir isotherm equation. The drug dissolution profile showed that HPCH‐<jats:italic>g</jats:italic>‐CM <jats:italic>β</jats:italic>‐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 <jats:italic>β</jats:italic>‐CD grafted with chitosan derivatives may become a potential biodegradable delivery system to control the release of hydrophobic drugs with pH‐responsive capability.</jats:p><jats:p><jats:boxed-text content-type="graphic" position="anchor"><jats:caption><jats:p>The structure and drug release profiles of HPCH‐<jats:italic>g</jats:italic>‐CM <jats:italic>β</jats:italic>‐CD.</jats:p></jats:caption><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" mimetype="image/gif" position="anchor" specific-use="enlarged-web-image" xlink:href="graphic/mgra001.gif"><jats:alt-text>magnified image</jats:alt-text><jats:caption><jats:p>The structure and drug release profiles of HPCH‐<jats:italic>g</jats:italic>‐CM <jats:italic>β</jats:italic>‐CD.</jats:p></jats:caption></jats:graphic></jats:boxed-text> </jats:p>