Drug controlled release from structured bioresorbable films used in medical devices--a mathematical model

A mathematical model for predicting drug release profiles from structured bioresorbable films was developed and studied. These films, which combine good mechanical properties with desired drug release profiles, are designed for use in various biomedical applications. Our structured polymer/drug films are prepared using a promising technique for controlling the drug location/dispersion in the film. The present model was used for predicting drug release profiles from two film types that is films in which the drug is located on the surface (A-type) and films in which the drug is located in the bulk (B-type). The model is based on Fick's 2nd law of diffusion and assumes that the drug release profile from the films is affected by the host polymer's characteristics, the drug location/dispersion in the film and the drug's characteristics. This semiempirical model uses the weight loss profile of the host polymers as well as the change in their degree of crystallinity with degradation. Our study indicates that the model correlates well with in vitro release results, exhibiting a mean error of less than 7% for most studied cases. It also shows that the host polymer's degradation has a greater effect on the drug release profile than the degree of crystallinity. This new model exhibits a potential for simulating the release profile of bioactive agents from structured films for a wide variety of biomedical applications.