Drug release from a N-vinylpyrrolidinone/acrylic acid lubricious hydrophilic coating

Initial characterisation was performed on different crosslinked hydrogels to determine the suitability for coating applications. The test used in the initial stage of the work was swelling studies. From this test a suitable monomeric concentration was decided upon. The coating was applied to the Pebax® 3533 substrate using a dip coating/UV curing procedure. The coating was characterised by measuring the coating thickness, the relative viscosity, the density and the contact angle it made with the substrate. The coating was analysed using Ftir, optical microscopy and friction analysis to characterise the lubricious nature of the coating. From this analysis it was found that 2 coating cycles were necessary to give a good coverage thoughout the entire length of the substrate, and that the static coefficient was significantly reduced from that of the uncoated samples when the coating was hydrated for 10 min or more. Finally the release profile of aspirin was determined using UV spectroscopy, where it was found that the release rate could be controlled by varying the molecular weight of the crosslinking agents used.