Oxidation of lipids and lipoproteins contributes to inflammation processes that promote the development of eye diseases. This is a consequence of metabolism dysregulation; for instance, that of the dysfunctional peroxisomal lipid metabolism. Dysfunction of lipid peroxidation is a critical factor in oxidative stress that causes ROS-induced cell damage. Targeting the lipid metabolism to treat ocular diseases is an interesting and effective approach that is now being considered. Indeed, among ocular structures, retina is a fundamental tissue that shows high metabolism. Lipids and glucose are fuel substrates for photoreceptor mitochondria; therefore, retina is rich in lipids, especially phospholipids and cholesterol. The imbalance in cholesterol homeostasis and lipid accumulation in the human Bruch’s membrane are processes related to ocular diseases, such as AMD. In fact, preclinical tests are being performed in mice models with AMD, making this area a promising field. Nanotechnology, on the other hand, offers the opportunity to develop site-specific drug delivery systems to ocular tissues for the treatment of eye diseases. Specially, biodegradable nanoparticles constitute an interesting approach to treating metabolic eye-related pathologies. Among several drug delivery systems, lipid nanoparticles show attractive properties, e.g., no toxicological risk, easy scale-up and increased bioavailability of the loaded active compounds. This review analyses the mechanisms involved in ocular dyslipidemia, as well as their ocular manifestations. Moreover, active compounds as well as drug delivery systems which aim to target retinal lipid metabolism-related diseases are thoroughly discussed.

This study aims to evaluate the feasibility of producing acyclovir-containing modified release matrix tablets by a wet granulation method based on the type and concentration of two pharmaceutical-grade hydrophilic matrix polymers (i.e., hydroxypropyl methylcellulose (HPMC), carbomers, and their combinations) commonly used in biomedical applications. The mechanical properties of the tablets and in vitro and in vivo performance were studied. The physicochemical properties of the raw materials and corresponding physical mixtures were characterized by differential scanning calorimetry, showing that the hydrophilic polymers did not influence the physicochemical properties of the drug. The wet granulation process improved the flow and compression properties of the obtained granules. This method enabled the preparation of the matrix tablets of acyclovir with appropriate mechanical properties concerning hardness and friability. The drug release kinetics was governed by the type and concentration of the hydrophilic polymers composing the matrices. The study has proven that HPMC-composed tablets were superior in modified drug release properties compared to carbomer- and HPMC/carbomer-based tablets. Mathematical analysis of the release profiles, determined in a medium adjusted to pH 1.2 followed by pH 7.4, revealed that the drug released from the hydrophilic tablets followed non-Fickian first-order kinetics. An optimal HPMC-based formulation submitted to accelerated stability studies (40 °C, 75% RH) was stable for three months. A complete cross-over bioavailability study of the selected acyclovir-loaded sustained release tablets and marketed immediate-release tablets were compared in six healthy male volunteers. The extent of drug absorption from the sustained release tablets was significantly greater than that from immediate-release pills, which may improve the drug’s antiviral properties attributed to the lower elimination rate and enhanced acyclovir half-life.