Nanomedicines for the treatment of glaucoma: Current status and future perspectives

Nanomedicine in glaucoma treatment; Current challenges and future perspectives

Glaucoma presents a significant global health concern and affects millions of individuals worldwide and predicted a high increase in prevalence of about 111 million by 2040. The current standard treatment involves hypotensive eye drops; however, challenges such as patient adherence and limited drug bioavailability hinder the treatment effectiveness. Nanopharmaceuticals or nanomedicines offer promising solutions to overcome these obstacles. In this manuscript, we summarized the current limitations of conventional antiglaucoma treatment, role of nanomedicine in glaucoma treatment, rational design, factors effecting the performance of nanomedicine and different types of nanocarriers in designing of nanomedicine along with their applications in glaucoma treatment from recent literature. Current clinical challenges that hinder real-time application of antiglaucoma nanomedicine are highlighted. Lastly, future directions are identified for improving the therapeutic potential and translation of antiglaucoma nanomedicine into clinic.

A one-platform comparison study of brinzolamide-loaded liposomes, niosomes, transfersomes, and transniosomes for better management of glaucoma

Ocular drug delivery presents significant challenges due to various anatomical and physiological barriers. Ultradeformable vesicles have emerged as better vesicular systems for achieving deeper corneal penetration and enhanced ocular bioavailability. This research aims to develop a hybrid vesicular system with improved deformability and compare it to conventional vesicular carriers. The ultradeformable vesicle, termed "transniosomes," is a combination of niosomes, liposomes, and transfersomes, loaded with brinzolamide as model drug. The brinzolamide-loaded transniosomes (BRZ-TN) was formulated and compared with different vesicular systems through in vitro, ex vivo, and in vivo characterizations. The optimized BRZ-TN demonstrated a vesicle size of 112.06 ± 4.13 nm and an entrapment efficiency of 93.63 ± 0.30 %. With a deformability index of 6.405, the BRZ-TN exhibited a permeability of 86.68 ± 2.51 % over 10 h, which is approximately 1.3 times higher than other conventional vesicular systems. Additionally, the BRZ-TN showed a drug flux of 0.247 ± 0.01 mg/cm2/h and an apparent permeability of 0.09 ± 1.21 cm/s. Pre-clinical experiments confirmed the superiority of the optimized BRZ-TN, achieving a 37 % reduction in intraocular pressure (IOP), post 6hr of administration, indicating its prolonged therapeutic effect and improved ocular bioavailability. The findings of this study suggest that transniosomes are superior to other carriers and hold great promise as a nanocarrier for ocular drug delivery.

Anti-oxidative mesoporous polydopamine-based hypotensive nano-eyedrop for improved glaucoma management

Conventional hypotensive eye drops remain suboptimal for glaucoma management, primarily due to their limited intraocular bioavailability and the growing concern regarding ocular surface side effects. Therefore, there is an urgent need to develop innovative intraocular pressure (IOP)-lowering formulations that not only possess enhanced corneal penetration ability but also provide ocular surface protection. Herein, anti-oxidative mesoporous polydopamine nanoparticles (MPDA NPs) were explored as a nano-carrier for Brimonidine to address the above issues. Nearly monodisperse MPDA NPs with obvious nanopores were successfully prepared by template-removal method and used for encapsulation of Brimonidine benefiting from their high specific surface area. Interestingly, the PEGylated and drug loaded MPDA-PEG@Brim NPs showed a near neutral surface charge, which is expected to enhance intraocular drug delivery. Consequently, much higher concentration of Brimonidine in the aqueous humor was found after topical administration of MPDA-PEG@Brim nano-dispersion as compared to free Brimonidine solution. Accordingly, superior IOP reduction effect was achieved for the nano-formulation in both hypertensive and normotensive rat eyes. Moreover, MPDA-PEG NPs showed good capability in scavenging diverse free radicals, alleviating intracellular oxidative stress, and mitigating ocular surface oxidative level in a mouse model of preservative-induced dry eye. In addition, the excellent biosafety of this novel Brimonidine nanodrug was confirmed both in vitro and in vivo. Therefore, the present work may shed light on the development of next generation hypotensive formulations for extended ocular surface protection and glaucoma management.

Sustained release of brimonidine from conjunctival sac insert to reduce intraocular pressure for glaucoma treatment

BACKGROUND

Glaucoma is one of the major irreversible blinding eye diseases in the world. Reducing intraocular pressure (IOP) is the primary treatment option, and taking eye drops daily is the common method. However, short drug duration and poor bioavailability of eye drops may lead to unsatisfied therapeutic effects and inadequate patient compliance.

METHODS

A brimonidine-loaded silicone rubber insert (BRI@SR@PT) was prepared by loading brimonidine into a surface-modified silicone rubber ring, followed by polydopamine/thermoplastic polyurethane coatings. The physical properties, in vitro cytocompatibility and drug release of BRI@SR@PT were investigated. The BRI@SR@PT was administrated in the conjunctival sac of rabbit eyes, and its in vivo drug release, IOP-lowering efficacy and biosafety were assessed.

RESULTS

The BRI@SR@PT presented great thermal stability and excellent elasticity. The BRI@SR@PT was able to release BRI sustainably for 28 days with little toxicity in vitro. Compared to BRI eye drops, the BRI@SR@PT effectively lowered IOP for 21 days based on the sustained BRI release with great biosafety when administrated in conjunctival sac of rabbit eyes in a noninvasive fashion.

CONCLUSIONS

The conjunctival sac insert (BRI@SR@PT), as a promising drug-delivery platform, may provide a sustained IOP-lowering treatment for patients with ocular hypertension or glaucoma, without the need for invasive procedures.

Light-responsive polymeric nanoparticles for retinal drug delivery: design cues, challenges and future perspectives

A multitude of sight-threatening retinal diseases, affecting hundreds of millions around the globe, lack effective pharmacological treatments due to ocular barriers and common drug delivery limitations. Polymeric nanoparticles (PNPs) are versatile drug carriers with sustained drug release profiles and tunable physicochemical properties which have been explored for ocular drug delivery to both anterior and posterior ocular tissues. PNPs can incorporate a wide range of drugs and overcome the challenges of conventional retinal drug delivery. Moreover, PNPs can be engineered to respond to specific stimuli such as ultraviolet, visible, or near-infrared light, and allow precise spatiotemporal control of the drug release, enabling tailored treatment regimens and reducing the number of required administrations. The objective of this study is to emphasize the therapeutic potential of light-triggered drug-loaded polymeric nanoparticles to treat retinal diseases through an exploration of ocular pathologies, challenges in drug delivery, current production methodologies and recent applications. Despite challenges, light-responsive PNPs hold the promise of substantially enhancing the treatment landscape for ocular diseases, aiming for an improved quality of life for patients.

Dendrimer and dendrimer gel-derived drug delivery systems: Breaking bottlenecks of topical administration of glaucoma medications

Due to high structural flexibility, multidrug carrying capability, and tunable size, dendrimers have been used as suitable carriers for ophthalmic drug delivery. Drug molecules can be either encapsulated or chemically coupled to dendrimers. The nanoscopic size, spheroidal shape, and cationic surface of polyamidoamine (PAMAM) dendrimers promote their interaction with the cornea and result in prolonged precorneal retention. Dendrimers could be further cross-linked to produce three-dimensional hydrogel networks or dendrimer hydrogels (DH). The properties of the DH can be readily adjusted to maintain both fluidity and adhesiveness, making them suitable for developing topical ocular drug formulations. Micro-/nano-sized DHs, that is, dendrimer micro-/nano-gels, have unique properties such as ease of administration, large specific surface area for adhesion, and drug targeting functionalities, making them attractive for ophthalmic drug delivery. This perspective reports advances in PAMAM dendrimer based drug delivery systems including drug conjugates and micro- and nano-gels to enhance and sustain the delivery of multiple anti-glaucoma drugs, Dendrimer and dendrimer gel-derived drug delivery systems hold great potential as multifunctional topical drug delivery systems for the eye.

Glaucoma and Ocular Surface Disease: More than Meets the Eye

Understanding the association between ocular surface disease and glaucoma is important for improving adherence to treatment and introducing practical solutions. While topical antihypertensive medications for glaucoma are well tolerated according to short-term studies, there is little evidence on their long-term effects. Since they are often required for many years, the effects of these drops on the ocular surface become important in regard to quality of life and adherence. In this nonsystematic review performed in April 2022, we summarize what is known about the relationship between glaucoma and ocular surface disease. Specifically, we examine how each class of topical glaucoma drops affects the ocular surface. We then review the treatment of ocular surface disease for patients on topical glaucoma therapy. Finally, we discuss treatments that may reduce or eliminate the burden of topical medications.

An Update on Novel Ocular Nanosystems with Possible Benefits in the Treatment of Corneal Neovascularization

Corneal neovascularization (CNV) is an ocular pathological change that results from an imbalance between angiogenic factors and antiangiogenic factors as a result of various ocular insults, including infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation. Current clinical strategies for the treatment of CNV include pharmacological treatment and surgical intervention. Despite some degree of success, the current treatment strategies are restricted by limited efficacy, adverse effects, and a short duration of action. Recently, gene-based antiangiogenic therapy has become an emerging strategy that has attracted considerable interest. However, potential complications with the use of viral vectors, such as potential genotoxicity resulting from long-term expression and nonspecific targeting, cannot be ignored. The use of ocular nanosystems (ONS) based on nanotechnology has emerged as a great advantage in ocular disease treatment during the last two decades. The potential functions of ONS range from nanocarriers, which deliver drugs and genes to target sites in the eye, to therapeutic agents themselves. Various preclinical studies conducted to date have demonstrated promising results of the use of ONS in the treatment of CNV. In this review, we provide an overview of CNV and its current therapeutic strategies and summarize the properties and applications of various ONS related to the treatment of CNV reported to date. Our goal is to provide a comprehensive review of these considerable advances in ONS in the field of CNV therapy over the past two decades to fill the gaps in previous related reports. Finally, we discuss existing challenges and future perspectives of the use of ONS in CNV therapy, with the goal of providing a theoretical contribution to facilitate future practical growth in the area.

Hotspots and trends in ophthalmology in recent 5 years: Bibliometric analysis in 2017–2021

Purpose

The purpose of this study was to investigate the hotspots and research trends of ophthalmology research.

Method

Ophthalmology research literature published between 2017 and 2021 was obtained in the Web of Science Core Collection database. The bibliometric analysis and network visualization were performed with the VOSviewer and CiteSpace. Publication-related information, including publication volume, citation counts, countries, journals, keywords, subject categories, and publication time, was analyzed.

Results

A total of 10,469 included ophthalmology publications had been cited a total of 7,995 times during the past 5 years. The top countries and journals for the number of publications were the United States and the Ophthalmology. The top 25 global high-impact documents had been identified using the citation ranking. Keyword co-occurrence analysis showed that the hotspots in ophthalmology research were epidemiological characteristics and treatment modalities of ocular diseases, artificial intelligence and fundus imaging technology, COVID-19-related telemedicine, and screening and prevention of ocular diseases. Keyword burst analysis revealed that “neural network,” “pharmacokinetics,” “geographic atrophy,” “implementation,” “variability,” “adverse events,” “automated detection,” and “retinal images” were the research trends of research in the field of ophthalmology through 2021. The analysis of the subject categories demonstrated the close cooperation relationships that existed between different subject categories, and collaborations with non-ophthalmology-related subject categories were increasing over time in the field of ophthalmology research.

Conclusions

The hotspots in ophthalmology research were epidemiology, prevention, screening, and treatment of ocular diseases, as well as artificial intelligence and fundus imaging technology and telemedicine. Research trends in ophthalmology research were artificial intelligence, drug development, and fundus diseases. Knowledge from non-ophthalmology fields is likely to be more involved in ophthalmology research.

Untangling Mucosal Drug Delivery: Engineering, Designing, and Testing Nanoparticles to Overcome the Mucus Barrier

Mucus is a complex viscoelastic gel and acts as a barrier covering much of the soft tissue in the human body. High vascularization and accessibility have motivated drug delivery to various mucosal surfaces; however, these benefits are hindered by the mucus layer. To overcome the mucus barrier, many nanomedicines have been developed, with the goal of improving the efficacy and bioavailability of drug payloads. Two major nanoparticle-based strategies have emerged to facilitate mucosal drug delivery, namely, mucoadhesion and mucopenetration. Generally, mucoadhesive nanoparticles promote interactions with mucus for immobilization and sustained drug release, whereas mucopenetrating nanoparticles diffuse through the mucus and enhance drug uptake. The choice of strategy depends on many factors pertaining to the structural and compositional characteristics of the target mucus and mucosa. While there have been promising results in preclinical studies, mucus-nanoparticle interactions remain poorly understood, thus limiting effective clinical translation. This article reviews nanomedicines designed with mucoadhesive or mucopenetrating properties for mucosal delivery, explores the influence of site-dependent physiological variation among mucosal surfaces on efficacy, transport, and bioavailability, and discusses the techniques and models used to investigate mucus-nanoparticle interactions. The effects of non-homeostatic perturbations on protein corona formation, mucus composition, and nanoparticle performance are discussed in the context of mucosal delivery. The complexity of the mucosal barrier necessitates consideration of the interplay between nanoparticle design, tissue-specific differences in mucus structure and composition, and homeostatic or disease-related changes to the mucus barrier to develop effective nanomedicines for mucosal delivery.

Current situation and progress of drugs for reducing intraocular pressure

Glaucoma, the most common cause of irreversible blindness worldwide, usually causes characteristic optic nerve damage. Pathological intraocular pressure (IOP) elevation is a major risk factor. Drug reduction of IOP is the preferred treatment for clinicians because it can delay the progression of disease. However, the traditional IOP-lowering drugs currently used by patients may be poorly tolerated. Therefore, in recent years, some new drugs have been put into clinical application or in clinical phase I–III studies. They have a better IOP-lowering effect and fewer adverse reactions. Because glaucoma is a chronic disease, drugs need to be administered continuously for a long time. For patients, good compliance and high drug bioavailability have a positive effect on the prognosis of the disease. Therefore, clinicians and scientists have developed drug delivery systems to solve this complex problem. In addition, natural compounds and dietary supplements have a good effect of reducing IOP, and they can also protect the optic nerve through antioxidant action. We summarize the current traditional drugs, new drugs, sustained-release drug delivery systems, and complementary drugs and outline the mechanism of action and clinical effects of these drugs on glaucoma and their recent advances.

Advances in the application of nanotechnology in reducing cardiotoxicity induced by cancer chemotherapy

Advances in the development of anti-tumour drugs and related technologies have resulted in a significant increase in the number of cancer survivors. However, the incidence of chemotherapy-induced cardiotoxicity (CIC) has been rising continuously, threatening their long-term survival. The integration of nanotechnology and biomedicine has brought about an unprecedented technological revolution and has promoted the progress of anti-tumour therapy. In this review, we summarised the possible mechanisms of CIC, evaluated the role of nanoparticles (including liposomes, polymeric micelles, dendrimers, and hydrogels) as drug carriers in preventing cardiotoxicity and proposed five advantages of nanotechnology in reducing cardiotoxicity: Liposomes cannot easily penetrate the heart's endothelial barrier; optimized delivery strategies reduce distribution in important organs, such as the heart; targeting the tumour microenvironment and niche; stimulus-responsive polymer nano-drug carriers rapidly iterate; better economic benefits were obtained. Nanoparticles can effectively deliver chemotherapeutic drugs to tumour tissues, while reducing the toxicity to heart tissues, and break through the dilemma of existing chemotherapy to a certain extent. It is important to explore the interactions between the physicochemical properties of nanoparticles and optimize the highly specific tumour targeting strategy in the future.