Cyclodextrin-polyhydrazine degradable gels for hydrophobic drug delivery

• Injectable hydrogels were prepared as hydrophobic drug carriers.
• Improvement of the aqueous solubility of a lipophilic drug was obtained via inclusion complex formation.
• Mechanical properties, degradation and swelling behaviour depend on the crosslinking density of the matrices.
• Controlled release of a hydrophobic drug can be achieved by control of cross-link density

An injectable and biocompatible hydrogel system was designed for hydrophobic drug delivery. This hydrogel consisted of degradable polymers with cyclodextrin (CD) moieties. CD groups were used to increase the solubility of a hydrophobic molecule (nicardipine) in an aqueous solution through the formation of the inclusion complex. Two sets of gels were prepared by mixing oxidized dextran (DA) and CD functionalized polyhydrazine (PH) at physiological conditions and different level of crosslinking via hydrazone bonds. Cytotoxicity studies on the gels and their components confirmed the biocompatibility of these materials. Gel-30 with higher crosslinking density showed a two week degradation period whereas this period was 10 days for gel-10, with lower crosslinking density, to complete degradation. The results from swelling tests and rheological measurements were also found to be dependent on crosslinking density of the hydrogels. Release profile of the hydrogel displayed a sustained release of nicardipin up to 6 days for gel-30 and a 4 day release with initial burst release for gel-10.

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