COMPARATIVE IN-VITRO EVALUATION OF SEVERAL COLLOIDAL SYSTEMS, NANOPARTICLES, NANOCAPSULES, AND NANOEMULSIONS, AS OCULAR DRUG CARRIERS

Three different colloidal carriers, namely, nanoparticles and nanocaps ules made of poly-epsilon-caprolactone and submicron emulsions, were d esigned, and their capacity for increasing the corneal penetration of drugs was investigated, The three systems differed in their inner stru cture and composition, but they had a similar size (200-250 nm) and a negative superficial charge (-16 to -42 mV). Indomethacin, which was u sed as a model drug, was dispersed at a molecular level within the col loidal systems, no chemical interaction between the polymer and the dr ug being detected. Release of the encapsulated indomethacin occurred v ery rapidly upon high dilution in a buffered medium and was independen t of the composition of the system. The in vitro corneal penetration o f the encapsulated indomethacin was more than 3-fold that of the comme rcial eye drops. This increased penetration was similar for the three formulations investigated, which therefore excludes the influence of t he inner structure or chemical composition of the colloidal systems on the corneal penetration of indomethacin. Thus, it could be stated tha t the main factor responsible for the favorable corneal transport of i ndomethacin is the colloidal nature of these carriers rather than thei r inner structure or composition.