Structured drug-loaded bioresorbable films for support structures

Bioresorbable films can serve simultaneously as anatomic support structures and as drug delivery platforms. In the present study, bioresorbable PLLA f ilms containing dexamethasone were developed through solution processing. T he effect of processing parameters on the film morphology and the resulting mechanical properties was studied. A model describing the structuring of t hese films is suggested. Generally, the solvent evaporation rate determines the kinetics of drug and polymer crystallization and thus, both the mode o f drug dispersion in the polymer and the resulting mechanical properties. T wo types of structured films were studied: (1) a polymer film with drug loc ated on its surface, obtained due to drug skin formation accompanied by a l ater polymer core formation; and (2) a polymer film with small drug particl es and crystals distributed within the bulk, obtained by parallel solidific ation of the two components. A prototypical application of these films is a n expandable biodegradable support structure (stent), which we have develop ed. This stent demonstrated good initial mechanical properties. The film st ructure has only a minor effect on the stent radial compression strength, b ut more significantly affects the tensile mechanical properties.