be seen in fig6 b a large number of heparin particles are contained in the silicone material the substantially non porous surface of fig7 a typically occurs with an incorporation of an amount of non particulate material such as dexamethasone which partially or entirely dissolves in the solvent for the poly siloxane prior to coating and cure upon curing of the polymer and evaporation of the solvent depending on the loading of dexamethasone the dexamethasone reprecipitates in a hydrophobic crystalline form containing dendrite or even elongated hexagonal crystals approximately 5 microns in size as can be seen in fig7 b even after release of the incorporated material or three months the coating surface remains substantially non porous indicating the transport or diffusion of the drug outward through the silicone material neither requires nor produces gross pores the dexamethasone is incorporated in its more hydrophobic form rather than in one of the relatively more hydrophilic salt forms such as in a phosphate salt for example fig8 and 9 depict plots of total percent drug release related to long term drug release stent coating layers fig8 depicts the release of heparin from a 50 heparin loading in silicone the silicone was cured at 90 u00b0 c for 16 hours the heparin release took place in a phosphoric buffer ph 7 4 for 90 days at 37 u00b0 c the heparin concentration in the phosphoric buffer was analyzed by azure.