PEGylated PLGA nanospheres optimized by design of experiments for ocular administration of dexibuprofen in vitro, ex vivo and in vivo characterization

Dexibuprofen-loaded PEGylated PLGA nanospheres have been developed to improve the biopharmaceuti-cal profile of the anti-inflammatory drug for ocular administration. Dexibuprofen is the active enantiomerof ibuprofen and therefore lower doses may be applied to achieve the same therapeutic level. Accordingto this, two batches of nanospheres of different drug concentrations, 0.5 and 1.0 mg/ml respectively, havebeen developed (the latter corresponding to the therapeutic ibuprofen concentration for inflammatoryeye diseases). Both batches were composed of negatively charged nanospheres (-−14.1 and -−15.9 mV),with a mean particle size below 200 nm, and a high encapsulation efficiency (99%). X-ray, FTIR, and DSCanalyses confirmed that the drug was dispersed inside the matrix of the nanospheres. While the in vitrorelease profile was sustained up to 12 h, the ex vivo corneal and scleral permeation profile demonstratedhigher drug retention and permeation in the corneal tissue rather than in the sclera. These results werealso confirmed by the quantification of dexibuprofen in ocular tissues after the in vivo administration ofdrug-loaded nanospheres. Cell viability studies confirmed that PEGylated-PLGA nanospheres were lesscytotoxic than free dexibuprofen in the majority of the tested concentrations. Ocular in vitro (HET-CAMtest) and in vivo (Draize test) tolerance assays demonstrated the non-irritant character of both nanospherebatches. In vivo anti-inflammatory effects were evaluated in albino rabbits before and after inflammationinduction. Both batches confirmed to be effective to treat and prevent ocular inflammation. Keywords: Nanospheres, Dexibuprofen, PLGA, PEG, Inflammation, Drug delivery