nanocapsules emulsion h nanoparticles t �� celebrex attorney and michigan microparticles fig indomethacin concentrations attained in the aqueous humor following the topical application, in rabbits, of indomethacinloaded carriers and a control drug solution mean values � sd, n = , p celebrex attorney and michigan compared with indocollyre p compared with colloidal suspensions reprinted from ref , with permission from pharmaceutical press immunosuppressive peptide cyclosporin a interestingly, following topical administration of pecl nanocapsules containing cyclosporin a, we observed corneal levels of the drug which were five times higher than those provided by an oily solution topical formulation of cyclosporin typically used these high levels were not, celebrex attorney and michigan however, translated into high drug concentrations in the aqueous humor a result that was attributed to the important hydrophobicity of this peptide and its tendency to associate with lypophylic components therefore, at present, there is a proofofconcept of celebrex attorney and michigan the efficacy of polyester nanocapsules for enhancing the concentration of topically applied drugs in the corneal epithelium whether this enhanced concentration may or may not lead to a favored accumulation of the drug in the inner eye is expected to be largely dependent on the physicochemical characteristics of the drug polysaccharidebased nanoparticles the polyester polymers described above are hydrophobic polymers that need to be biodegraded into hydrophilic oligomers in order to be eliminated from the body a very different class of polymers, which has only received attention in the last few years, is the one represented by the hydrophilic polysaccharides hyaluronic acid and chitosan are two types of polysaccharides which have opened new prospects in the ocular drug delivery area the choice of hyaluronic acid has been celebrex attorney and michigan justified by its bioadhesive character, but also by celebrex attorney and michigan its well known safety profile in fact, hyaluronic acid is already being used as a substitute for vitreous humor in intraocular surgery, since it constitutes a basic component of the celebrex attorney and michigan vitreous body on the other hand, chitosan is a polycationic biopolymer which exhibits several favorable biological properties for ocular drug administration these properties include mucoadhesiveness biodegradability in the rich lysozyme containing mucus ie ocular mucosa, and also wound healing and antimicrobial activity despite the number of articles showing the efficacy of hyaluronic celebrex attorney and michigan acid solutions for improving the retention of drugs applied topically onto the eye, the only particulate formulation that has been tested in vivo celebrex attorney and michigan was composed of microparticles zm rather than nanoparticles these hyaluronate microparticles were shown to increase celebrex attorney and michigan the residence time of the model drug methylprednisolone at the ocular surface of the rabbit eye taking into account the reported influence of celebrex attorney and michigan the size on the interaction of particles with the ocular mucosa, we have recently designed nanoparticles consisting of hyaluronic acid and chitosan at present, we know that these nanoparticles are celebrex attorney and michigan stable upon incubation in simulated lachrymal fluids celebrex attorney and michigan and in vivo studies are in progress in order to evaluate their mechanism of interaction with the ocular mucosa chitosan has also received significant attention in the ophthalmic field one celebrex attorney and michigan of the chitosanbased systems that has exhibited an interesting behavior following topical ocular administration, is the one consisting of chitosan nanoparticles these nanoparticles have been tested on the rabbit model for their ability to enhance the concentration of celebrex attorney and michigan cyclosporin a at the level of the ocular mucosa as expected, the results showed that the chitosan nanoparticles were able to increase celebrex attorney and michigan the concentrations of cyclosporin a in the external testosterone and prostate weight ocular tissues cornea and conjunctiva significantly for up to hr postinstillation fig despite this enhanced retention of the drug in the external tissues, the levels attained in the internal ocular structures ie aqueous humor, iris and ciliary body and in the blood were negligible consequently, celebrex attorney and michigan these results suggested the utility of this celebrex attorney and michigan new formulation for the treatment of surface eye diseases, ie dry eye or inflammatory diseases these high drug concentrations restricted to the periocular tissues were later explained by a high corneal and conjunctival surface retention of chitosan nanoparticles celebrex attorney and michigan indeed, in a study consisting of evaluating the concentration of fluorescent chitosan, either in the form of nanoparticles or as a solution, in cornea and conjunctiva, we could conclude that the affinity of chitosan for the ocular surface is greater when it is in a particulate form this conclusion invites interesting prospects with regard to the potential of chitosan nanoparticles celebrex attorney and michigan as drug carriers for topical ocular administration celebrex attorney and michigan keeping this in mind, we tested the acute tolerance of chitosan nanoparticles following topical instillation celebrex attorney and michigan to rabbits very recently the results gave evidence of an excellent tolerance, without any sign of irritation or damage of the ocular surface celebrex attorney and michigan structures cya concentration in the cornea ng cyag cornea ?