Topical drug delivery is one of the most challenging aspects of eye therapy. Eye drops are the most prevalent drug form, especially for widely distributed anterior segment eye diseases (cataracts, glaucoma, dry eye syndrome, inflammatory diseases, etc.), because they are convenient and easy to apply by patients. However, conventional drug formulations are usually characterized by short retention time in the tear film, insufficient contact with epithelium, fast elimination, and difficulties in overcoming ocular tissue barriers. Not more than 5% of the total drug dose administered in eye drops reaches the interior ocular tissues. To overcome the ocular drug delivery barriers and improve drug bioavailability, various conventional and novel drug delivery systems have been developed. Among these, nanosize carriers are the most attractive. The review is focused on the different drug carriers, such as synthetic and natural polymers, as well as inorganic carriers, with special attention to nanoparticles and nanomicelles. Studies in vitro and in vivo have demonstrated that new formulations could help to improve the bioavailability of the drugs, provide sustained drug release, enhance and prolong their therapeutic action. Promising results were obtained with drug-loaded nanoparticles included in in situ gel.

Use of antioxidants to mitigate oxidative stress during ocular inflammatory diseases has shown therapeutic potential. This work examines a nanoscale therapeutic modality for the eye on the base of antioxidant enzyme, superoxide dismutase 1 (SOD1), termed “nanozyme.” The nanozyme is produced by electrostatic coupling of the SOD1 with a cationic block copolymer, poly(L‐lysine)‐poly(ethyleneglycol), followed by covalent cross‐linking of the complexes with 3,3′‐dithiobis(sulfosuccinimidylpropionate) sodium salt. The ability of SOD1 nanozyme as well as the native SOD1 to reduce inflammatory processes in the eye was examined in vivo in rabbits with immunogenic uveitis. Results suggested that topical instillations of both enzyme forms demonstrated anti‐inflammatory activity; however, the nanozyme was much more effective compared to the free enzyme in decreasing uveitis manifestations. In particular, we noted statistically significant differences in such inflammatory signs in the eye as the intensities of corneal and iris edema, hyperemia of conjunctiva, lens opacity, fibrin clots, and the protein content in aqueous humor. Clinical findings were confirmed by histological data. Thus, SOD1‐containing nanozyme is potentially useful therapeutic agent for the treatment of ocular inflammatory disorders.

Inflammatory eye diseases remain the most common clinical problem in ophthalmology. The secondary processes associated with inflammation, such as overproduction of reactive oxygen species (ROS) and exhaustion of the endogenous antioxidant system, frequently lead to tissue degeneration, vision blurring, and even blindness. Antioxidant enzymes, such as copper–zinc superoxide dismutase (SOD1), could serve as potent scavengers of ROS. However, their delivery into the eye compartments represents a major challenge due to the limited ocular penetration. This work presents a new therapeutic modality specifically formulated for the eye on the basis of multilayer polyion complex nanoparticles of SOD1 (Nano-SOD1), which is characterized by appropriate storage stability and pronounced therapeutic effect without side reactions such as eye irritation; acute, chronic, and reproductive toxicity; allergenicity; immunogenicity; mutagenicity even at high doses. The ability of Nano-SOD1 to reduce inflammatory processes in the eye was examined in vivo in rabbits with a model immunogenic uveitis—the inflammation of the inner vascular tract of the eye. It was shown during preclinical studies that topical instillations of Nano-SOD1 were much more effective compared to the free enzyme in decreasing uveitis manifestations. In particular, we noted statistically significant differences in such inflammatory signs in the eye as corneal and conjunctival edema, iris hyperemia, and fibrin clots. Moreover, Nano-SOD1 penetrates into interior eye structures more effectively than SOD itself and retains enzyme activity in the eye for a much longer period of time, decreasing inflammation and restoring antioxidant activity in the eye. Thus, the presented Nano-SOD1 can be considered as a potentially useful therapeutic agent for the treatment of ocular inflammatory disorders.

A method of preparing calcium phosphate particles containing the angiotensin-converting enzyme inhibitor lisinopril has been suggested. The influence of the conditions of preparation of the particles on their characteristics (size, ζ-potential values, and structure) has been determined. It has been demonstrated that, at a reduced temperature (4°C) of preparation, particles with hydrodynamic radii 40–100 nm with a hollow porous structure and high degree of crystallinity are formed, while at high temperatures (40°C), amorphous particles with hydrodynamic radii 60–230 nm are formed. A decrease of the pH value of a medium from 7.5 to 5.8 resulted in the appearance of only large particles with mean hydrodynamic radius of approximately 400 nm. Replacing the potential-determining Na⁺ ions with K⁺ resulted in a higher absolute value of the ζ potential (−15 ± 2 mV compared to −6 ± 1 mV). It has been demonstrated in the experiments in vivo that lisinopril incorporated in the calcium phosphate particles caused a significantly stronger (approximately 2 times) and prolonged decrease of the intraocular pressure when compared to the same inhibitor used in the form of an aqueous solution.

Glaucoma is a widespread neurodegenerative disease for which increased intraocular pressure (IOP) is a primary modifiable risk factor. Recently, we have observed that compounds with oxindole scaffolds are involved in the regulation of intraocular pressure and therefore have potential antiglaucomic activity. In this article, we present an efficient method for obtaining novel 2-oxindole derivatives via microwave-assisted (MW) decarboxylative condensation of substituted isatins with malonic and cyanoacetic acids. Various 3-hydroxy-2-oxindoles were synthesized using MW activation for 5–10 min with high yields (up to 98%). The influence of novel compounds applied in instillations on IOP was studied in vivo on normotensive rabbits. The lead compound was found to reduce the IOP by 5.6 Torr (ΔIOP for the widely used antiglaucomatousic drug timolol 3.5 Torr and for melatonin 2.7 Torr).