Liquid Crystalline Coated Drug Particles as a Potential Route to Long Acting Intravitreal Steroids

The aim of this study was to investigate the potential for coating drug particles with liquid crystalline lipids with a view to modifying drug dissolution behaviour in the particle form. Firstly, dissolution of a simple salicylic acid layer on a microscope slide, as a model system was shown to be hindered by the liquid crystal layer and was sensitive to the type of liquid crystal nanostructure present. Particles of sodium salicylate (hydrophilic) and triamcinolone acetonide (hydrophobic) were produced, and lipids applied to the drug surface using either mechanofusion or co-spray drying approaches. The coated sodium salicylate particles dissolved extremely rapidly. Triamcinolone acetonide particles on the other hand dissolved very slowly compared to uncoated triamcinolone acetonide particles, which indicated that the coating was in fact intact, and that drug solubility in the aqueous channels likely controlled the transport of drug into the dissolution medium. Whilst more investigation is required, these initial studies demonstrate a potentially useful strategy for controlling drug dissolution for applications such as intravitreal steroid injections.