Structured drug-eluting bioresorbable films: microstructure and release profile

Bioresorbable drug-eluting films can be used in many biomedical applications. Examples for such applications include biodegradable medical support devices which combine mechanical support with drug release and antibiotic-eluting film coatings for prevention of bacterial infections associated with orthopedic implants or during gingival healing. In the current study, bioresorbable drug-loaded polymer films are prepared by solution processing. Two film structures are studied: A polymer film with large drug crystals located on its surface (A-type) and a polymer film with small drug particles and crystals distributed within the bulk (B-type). The basic mode of drug dispersion/location in the film (A or B-type) is found to be determined mainly by the process of film formation and depends mainly on the solvent evaporation rate, whereas the drug's hydrophilicity has a minor effect on this structuring process. Most release profiles from A-type films exhibit a burst effect of approximately 30% and a second release stage that occurs at an approximately constant rate and is determined mainly by the polymer weight loss rate. An extremely high burst release is exhibited only by a very hydrophilic drug. The matrix (monolithic) nature of the B-type film enables release profiles that are determined mainly by the host polymer's degradation profile, with a very low burst effect in most of the studied systems. In addition to the drug location/ dispersion in the film, the host polymer and drug type also strongly affect the drug's release profile from the film. It has been demonstrated that appropriate selection of the process parameters and film components (polymer and drug) can yield film structures with desirable drug release behaviors. This can lead to the engineering of new bioresorbable drug-eluting film-based implants for various applications.