Compressed polymeric mini-matrices for drug release control

Matrices of reduced dimensions of either inert or swellable polymers for multiple-unit administration, containing diprophylline as the model drug, were made by compression. Some swellable mini-matrices prepared from poly(vinyl alcohol) were externally crosslinked by soaking in an acidic formalin solution, and subsequent drying and exposure to UV or thermal energy sources. The release kinetics of the model drug from the mini-matrices was investigated by analyzing the early time portion of the release curves according to a simplified exponential equation which allows the comprehension of the release mechanism. The results showed that the release kinetics may be Fickian or anomalous nonFickian depending on the solubility of the polymer employed. Zero-order release kinetics were obtained by using mini-matrices, which were crosslinked at the surface.