Hydrocortisone loaded poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) nanoparticles for topical ophthalmic administration: Preparation, characterization and evaluation of ophthalmic toxicity.

Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) nanoparticles (PHBV-NPs) to encapsulate hydrocortisone (HC) for topical ophthalmic administration were prepared and characterized. The technique used to prepare the nanoparticles (NPs) was emulsification/solvent evaporation. The obtained size was 237.3 ± 2.7 nm, suitable for topical ocular administration. The obtained results for the entrapment efficiency were between 1 and 2.5% and for the drug loading were around 0.5%. The release behaviour of HC from the PHBV-NPs was also analyzed, adjusting this to a Higuchi kinetic model. For the new drug delivery system developed the ocular toxicity profile was determined by viability studies carried out on bovine keratocytes, by a Hen's Egg Test - Chorioallantoic Membrane (HET-CAM) and by a Bovine Corneal Opacity and Permeability assay (BCOP). The obtained results concluded that the new system is no cytotoxic on bovine keratocytes and is neither irritating nor produces any alteration in the transparency and in the permeability of the cornea. Confocal studies were also performed and confirmed that PHBV-NPs are able to penetrate efficiently into the corneal tissue. This novel PHBV-based drug delivery system could be a good option for topical ophthalmic administration of drugs.