Cationized hyaluronic acid coated spanlastics for cyclosporine A ocular delivery: Prolonged ocular retention, enhanced corneal permeation and improved tear production

The aim of this work was to design and evaluate novel cationized hyaluronic acid coated spanlastics (CHASVs), with the immunosuppressive peptide cyclosporine A (CsA) as the model drug. CHASVs exhibited ideal size, zeta potential, pH, osmolarity and entrapment efficiency. The developed CHASVs provided a surface tension of 34.98 +/- 0.19 mN/m, a contact angle of 21.07 +/- 3.56 degrees and a viscosity of 9-12 mPa.s, which reflected favorable wetting and bioadhesion properties. From the in vitro release study, the sustain release property could also be seen. These proved the availability of CsA by ocular delivery was improved. With an apparent permeation coefficient of 5.22 x 10(-6) cm/s and CsA residual of 312.18 +/- 1.34 mu g/g, CHASVs proved to enhance corneal permeation and accumulation of CsA compared with commercial emulsions. In vivo Draize test showed no signs of acute and chronic ocular toxicity of CHASVs formulations to the eyes of rabbits. Finally, schirmer tear test, tear ferning test and histologic analysis reflected that CHASVs showed significant therapeutic effect and improved tear production in dry eye. Results revealed that CHASVs could be a promising delivery system for CsA and employed as an ideal alternative to commercial emulsions for the treatment of dry eye syndrome.