Modulation of drug release from hydrogels by using cyclodextrins: the case of nicardipine/beta-cyclodextrin system in crosslinked polyethylenglycol.

A simple approach is presented to modulate drug delivery from swellable systems by using complexants. The effect of complexants has been interpreted by means of simple mass balances on diffusing species and the involved relevant parameters have been individuated. The application of this strategy to the release of nicardipine (NIC) from swellable systems by using beta-cyclodextrin (CD) as complexant has evidenced the potential of the approach to tailor drug release. Crosslinked polyethyleneglycol has been synthesized, characterized and used as the swellable matrix. Swelling kinetics, NIC and CD diffusivities in the swollen matrix and NIC/CD phase solubility studies have been performed. The polymer matrix has been loaded with pure NIC or with NIC and CD at different ratios and release kinetics evaluated. Release profiles have shown that the presence of CD significantly affected drug delivery by decreasing the effective diffusivity of NIC. The higher the CD/NIC ratio the slower is the release. This effect has been interpreted on the basis of the proposed model and physically sound assumptions.