Solventless visible light-curable coating: II. Drug release, mechanical strength and photostability.

Solventless photocurable film coating was used to obtain modified release coatings. Different pore-forming agents were used to achieve immediate and sustained release of a blue dye contained in the coated pellets (non-pareil beads). A super-disintegrant, sodium starch glycolate, was used to obtain immediate release. When incorporated in the coating, this pore-former swelled and yielded large pores that demonstrated quick release of the marker dye while leaving behind the scaffold provided by the photocured polymer. Simple pore-formers (lactose and sodium chloride) dissolved away without swelling and provided a more sustained release profile. Release can be modified with the choice of material, number of layers and thickness of the coating. When release of sodium chloride and release of marker dye were simultaneously monitored, it was observed that at least 40-50% of the sodium chloride that was incorporated in the coating released before the dye was released through the coating showing that pore-formation preceded the release of the marker dye. The coupling factor between dye release and pore-formation was found to be dependent on the ratio of amount of solid pore-forming agent and volume of liquid monomer (S/L) of the coating. Also, studies demonstrate that the coating is photostable and can withstand handling stress.