Polycarboxylic acid nanoparticles for ophthalmic drug delivery: an ex vivo evaluation with human cornea.

In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyaerylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polyearboxylic (polyaerylic and polyitaconic) acid nanopartieles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polimerization technique with sizes in the range of 50 nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80-85% for polyaerylic acid nanoparticles and between 65-70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyaerylic acid nanopartieles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanopartieles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalniotofrical drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, AlphaganTM. [ABSTRACT FROM AUTHOR]