Development of biodegradable drug releasing polymeric cardiovascular stents and in vitro evaluation

Prednisolone acetate (PA) is insoluble in water and was chosen as a model drug for its anti-inflammatory/anti-proliferative functions. PA is incorporated into the film-based polymeric biodegradable stents to provide controlled local release of the drug during the mechanical support phase. Stent formulations were 3 mm in diameter with lengths of 150 mm. The polymer wall thickness was 145.0 +/- 4.0 microm for microsphere-containing PLGA 75 : 25 stents. The ATR-FTIR spectra showed biodegradable stent surfaces were free of drug and microspheres. Incorporation of PA into the stents increased the surface area when compared to empty and microsphere-incorporated stents. PA release from the stents containing chitosan microspheres was slower than the PA-only incorporated stents. The drug release from the stents coated with microsphere-containing PLGA 75 : 25 solutions was determined to be the slowest one (19.1% cumulative PA released in 32 days). The stents formulated with PLGA 75 : 25 polymers were considered to be more promising due to their suitable mechanical properties and controlled release of the drug.