Preparation and evaluation of solid lipid nanoparticles of baicalin for ocular drug delivery system in vitro and in vivo

Purpose: To prepare and evaluate the solid lipid nanoparticles of baicalin (BA-SLN) for ocular drug delivery system. Methods: The BA-SLN was prepared by emulsification/ultrasonication method. The appearance of BA-SLN was examined by the negative stain method. The mean diameter and zeta potential of BA-SLN were determined using a Zetasizer. The entrapment efficiency of BA-SLN was determined by Sephadex-G50 column. And the solid-state characterization of BA-SLN was analyzed by DSC and X-ray. The release of drug from BA-SLN was evaluated using dialysis bag diffusion technique. The effects of SLN on corneal permeability of baicalin were investigated in vitro, using isolated rabbit corneas. The in vivo ocular irritation of BA-SLN was tested by pathological section observation using rabbits. The pharmacokinetics was evaluated by microdialysis in the rabbit aqueous humors. Results: The results showed that the BA-SLN had an average diameter of 91.42 +/- 1.02 nm with a zeta potential of -33.5 +/- -1.28 mV and the entrapment efficiency of 62.45 +/- 1.67%. In vitro release studies indicated that the BA-SLN retained the drug entity better than the baicalin ophthalmic solutions (BA-SOL). In the pharmacokinetics studies, the AUC value of BA-SLN was 4.0-fold versus the BA-SOL (P < 0.01), and the Cmax value of BA-SLN versus the BA-SOL was 5.3-fold (P < 0.01). Conclusion: SLN can be used as a carrier to enhance ocular bioavailability of baicalin.