Factors affecting prednisolone release from hydrogels prepared with water-soluble dietary fibers, xanthan and locust bean gums.

The release behavior of prednisolone from hydrogels prepared with xanthan and locust bean gums was investigated. Newly developed equipment was employed in order to increase the gum concentration in the hydrogels. The apparent release rate of prednisolone from the hydrogels decreased with increasing gum concentration, suggesting that the diffusion of drug molecules was mainly controlled by the density of the three-dimensional network structure in the matrix. The effect of additives such as glycerin and sucrose on the release behavior of prednisolone was also investigated in detail. Drug release was significantly lowered by the addition of these compounds to these hydrogels. A linear relation was observed between the apparent release rate of prednisolone and microscopic viscosity of the hydrogels. These results indicated that the drug release could be controlled not only by the density of the network structure but also by the microscopic viscosity of the hydrogels.