Gantrez AN nanoparticles for ocular delivery of memantine: in vitro release evaluation in albino rabbits

AIM: To prepare and evaluate the in vitro release of memantine-loaded poly(anhydride) (Gantrez®) nanoparticles (NPs). The clinical safety and retinal toxicity caused by unloaded NPs after sub-Tenon and intravitreal ocular injections were also evaluated. METHODS: Preparation and characterization of this type of NP as well as the in vitro release study are described. Twenty-three healthy New Zealand rabbits were used for clinical and histological assessment after sub-Tenon and intravitreal ocular injections of unloaded NPs. RESULTS: The amount of drug associated with NPs was 55 µg of memantine/mg of NP. The release profile of memantine from this type of NPs was characterized by an initial burst effect, followed by continuous release of the drug for at least 15 days. No relevant complications were found during the clinical follow-up. The histological evaluation suggested that Gantrez NPs are well tolerated after sub-Tenon ocular injection and that signs of inflammation during the first days after intravitreal ocular injections can be considered a normal reaction of the eye's defence mechanism