Developing an in situ nanosuspension: a novel approach towards the efficient administration of poorly soluble drugs at the anterior eye

Nanosuspensions in ophthalmology: Overcoming challenges and enhancing drug delivery for eye diseases

This review article provides a comprehensive overview of the advancements in using nanosuspensions for controlled drug delivery in ophthalmology. It highlights the significance of ophthalmic drug delivery due to the prevalence of eye diseases and delves into various aspects of this field. The article explores molecular mechanisms, drugs used, and physiological factors affecting drug absorption. It also addresses challenges in treating both anterior and posterior eye segments and investigates the role of mucus in obstructing micro- and nanosuspensions. Nanosuspensions are presented as a promising approach to enhance drug solubility and absorption, covering formulation, stability, properties, and functionalization. The review discusses the pros and cons of using nanosuspensions for ocular drug delivery and covers their structure, preparation, characterization, and applications. Several graphical representations illustrate their role in treating various eye conditions. Specific drug categories like anti-inflammatory drugs, antihistamines, glucocorticoids, and more are discussed in detail, with relevant studies. The article also addresses current challenges and future directions, emphasizing the need for improved nanosuspension stability and exploring potential technologies. Nanosuspensions have shown substantial potential in advancing ophthalmic drug delivery by enhancing solubility and absorption. This article is a valuable resource for researchers, clinicians, and pharmaceutical professionals in this field, offering insights into recent developments, challenges, and future prospects in nanosuspension use for ocular drug delivery.

Recent advances in nanocrystal-based technologies applied for ocular drug delivery

INTRODUCTION

The intricate physiological barriers of the eye and the limited volume of eye drops impede efficient delivery of poorly water-soluble drugs. In the last decade, nanocrystals have emerged as versatile drug delivery systems in various administration routes from bench to bedside. The unique superiorities of nanocrystals, mainly embodied in high drug-loading capacity, good mucosal adhesion and penetration, and greatly improved drug solubility, reveal a promising prospect for ocular delivery of poorly water-soluble drugs.

AREAS COVERED

This article focuses on the ophthalmic nanocrystal technologies and products that are in the literature, clinical trials, and even on the market. The recent research progress in the preparation, ocular application, and absorption of nanocrystals are highlighted, and the pros and cons of nanocrystals in overcoming the physiological barriers of the eye are also summarized.

EXPERT OPINION

Nanocrystals have demonstrated success as glucocorticoid eye drops in the treatment of anterior segment diseases. However, the thermodynamic stability of nanocrystals remains the major challenge in product development. New technologies for efficiently optimizing stabilizers and sterilization processes are still expected. Strategies to confer more diverse functions via surface modification are also worth exploration to improve the potential of nanocrystals in delivering poorly water-soluble drugs to posterior segment of the eye.

Novel drug delivery systems for the management of dry eye

Dry eye disease (DED) is a frequently observed eye complaint, which has recently attracted considerable research interest. Conventional therapy for DED involves the use of artificial tear products, cyclosporin, corticosteroids, mucin secretagogues, antibiotics and nonsteroidal anti-inflammatory drugs. In addition, ocular drug delivery systems based on nanotechnology are currently the focus of significant research effort and several nanotherapeutics, such as nanoemulsions, nanosuspensions, microemulsions, liposomes and nanomicelles, are in clinical trials and some have FDA approval as novel treatments for DED. Thus, there has been remarkable progress in the design of nanotechnology-based approaches to overcome the limitations of ophthalmic formulations for the management of anterior eye diseases. This review presents research results on diagnostic methods for DED, current treatment options, and promising pharmaceuticals as future therapeutics, as well as new ocular drug delivery systems.

Cyclosporine Lipid Nanocapsules as Thermoresponsive Gel for Dry Eye Management: Promising Corneal Mucoadhesion, Biodistribution and Preclinical Efficacy in Rabbits

An ophthalmic cyclosporine (CsA) formulation based on Lipid nanocapsules (LNC) was developed for dry eye management, aiming to provide targeting to ocular tissues with long-term drug levels and maximum tolerability. CsA-LNC were of small particle size (41.9 ± 4.0 nm), narrow size distribution (PdI ≤ 0.1), and high entrapment efficiency (above 98%). Chitosan (C) was added to impart positive charge. CsA-LNC were prepared as in-situ gels using poloxamer 407 (P). Ex vivo mucoadhesive strength was evaluated using bovine cornea, while in vivo corneal biodistribution (using fluorescent DiI), efficacy in dry eye using Schirmer tear test (STT), and ocular irritation using Draize test were studied in rabbits compared to marketed ophthalmic CsA nanoemulsion (CsA-NE) and CsA in castor oil. LNC incorporation in in-situ gels resulted in an increase in mucoadhesion, and stronger fluorescence in corneal layers seen by confocal microscopy, compared to the other tested formulations. Rate of recovery (days required to restore corneal baseline hydration level) assessed over 10 days, showed that CsA-LNC formulations produced complete recovery by day 7 comparable to CsA-NE. No Ocular irritation was observed by visual and histopathological examination. Based on data generated, CsA-LNC-CP in-situ gel proved to be a promising effective nonirritant CsA ophthalmic formulation for dry eye management.

Significance of Crosslinking Approaches in the Development of Next Generation Hydrogels for Corneal Tissue Engineering

Medical conditions such as trachoma, keratoconus and Fuchs endothelial dystrophy can damage the cornea, leading to visual deterioration and blindness and necessitating a cornea transplant. Due to the shortage of donor corneas, hydrogels have been investigated as potential corneal replacements. A key factor that influences the physical and biochemical properties of these hydrogels is how they are crosslinked. In this paper, an overview is provided of different crosslinking techniques and crosslinking chemical additives that have been applied to hydrogels for the purposes of corneal tissue engineering, drug delivery or corneal repair. Factors that influence the success of a crosslinker are considered that include material composition, dosage, fabrication method, immunogenicity and toxicity. Different crosslinking techniques that have been used to develop injectable hydrogels for corneal regeneration are summarized. The limitations and future prospects of crosslinking strategies for use in corneal tissue engineering are discussed. It is demonstrated that the choice of crosslinking technique has a significant influence on the biocompatibility, mechanical properties and chemical structure of hydrogels that may be suitable for corneal tissue engineering and regenerative applications.

Formulation Considerations for the Management of Dry Eye Disease

Dry eye disease (DED) is one of the most common ocular surface disorders characterised by a deficiency in quality and/or quantity of the tear fluid. Due to its multifactorial nature involving several inter-related underlying pathologies, it can rapidly accelerate to become a chronic refractory condition. Therefore, several therapeutic interventions are often simultaneously recommended to manage DED efficiently. Typically, artificial tear supplements are the first line of treatment, followed by topical application of medicated eyedrops. However, the bioavailability of topical eyedrops is generally low as the well-developed protective mechanisms of the eye ensure their rapid clearance from the precorneal space, thus limiting ocular penetration of the incorporated drug. Moreover, excipients commonly used in eyedrops can potentially exhibit ocular toxicity and further exacerbate the signs and symptoms of DED. Therefore, formulation development of topical eyedrops is rather challenging. This review highlights the challenges typically faced in eyedrop development, in particular, those intended for the management of DED. Firstly, various artificial tear supplements currently on the market, their mechanisms of action, as well as their application, are discussed. Furthermore, formulation strategies generally used to enhance ocular drug delivery, their advantages and limitations, as well as their application in commercially available DED eyedrops are described.

Glaucoma: Management and Future Perspectives for Nanotechnology-Based Treatment Modalities

Glaucoma, being asymptomatic for relatively late stage, is recognized as a worldwide cause of irreversible vision loss. The eye is an impervious organ that exhibits natural anatomical and physiological barriers which renders the design of an efficient ocular delivery system a formidable task and challenge scientists to find alternative formulation approaches. In the field of glaucoma treatment, smart delivery systems for targeting have aroused interest in the topical ocular delivery field owing to its potentiality to oppress many treatment challenges associated with many of glaucoma types. The current momentum of nano-pharmaceuticals, in the development of advanced drug delivery systems, hold promises for much improved therapies for glaucoma to reduce its impact on vision loss. In this review, a brief about glaucoma; its etiology, predisposing factors and different treatment modalities has been reviewed. The diverse ocular drug delivery systems currently available or under investigations have been presented. Additionally, future foreseeing of new drug delivery systems that may represent potential means for more efficient glaucoma management are overviewed. Finally, a gab-analysis for the required investigation to pave the road for commercialization of ocular novel-delivery systems based on the nano-technology are discussed.

The Role of Nano-ophthalmology in Treating Dry Eye Disease

Dry eye disease (DED) is a common multifactorial disease linked to the tears/ocular surface leading to eye discomfort, ocular surface damage, and visual disturbance. Antiinflammatory agents (steroids and cyclosporine A), hormonal therapy, antibiotics, nerve growth factors, essential fatty acids are used as treatment options of DED. Current therapies attempt to reduce the ocular discomfort by producing lubrication and stimulating gland/nerve(s) associated with tear production, without providing a permanent cure for dry eye. Nanocarrier systems show a great promise to revolutionize drug delivery in DED, offering many advantages such as site specific and sustained delivery of therapeutic agents. This review presents an overview, pathophysiology, prevalence and etiology of DED, with an emphasis on preclinical and clinical studies involving the use of nanocarrier systems in treating DED. Lay Summary: Dry eye disease (DED) is a multifactorial disease associated with tear deficiency or excessive tear evaporation. There are several review articles that summarize DED, disease symptoms, causes and treatment approaches. Nanocarrier systems show a great promise to revolutionize drug delivery in DED, offering many advantages such as site specific and sustained delivery of therapeutic agents. Very few review articles summarize the findings on the use of nanotherapeutics in DED. In this review, we have exclusively discussed the preclinical and clinical studies of nanotherapeutics in DED therapy. This information will be attractive to both academic and pharmaceutical industry researchers working in DED therapeutics.

Proniosomes derived niosomes: recent advancements in drug delivery and targeting

Vesicular drug delivery systems have gained wide attention in the field of nanotechnology. Among them proniosomes become the superior over other vesicular carriers. Proniosomes are dry formulations of water soluble nonionic surfactant coated carrier system which immediately forms niosomes upon hydration. They have the capability to overcome the instability problems associated with niosomes and liposomes and have the potential to improve solubility, bioavailability, and absorption of various drugs. Furthermore, they offer versatile drug delivery concept for enormous number of hydrophilic and hydrophobic drugs. They have the potential to deliver drugs effectively through different routes at specific site of action to achieve controlled release action and reduce toxic effects associated with drugs. This review discusses the general preparation techniques of proniosomes and mainly focus on the applications of proniosomes in drug delivery and targeting. Moreover, this review demonstrates critical appraisal of the literature for proniosomes. Additionally, this review extensively explains the potential of proniosomes in delivering drugs via different routes, such as oral, parenteral, dermal and transdermal, ocular, oral mucosal, vaginal, pulmonary, and intranasal. Finally, the comparison of proniosomes with niosomes manifests the clear distinction between them. Moreover, proniosomes need to be explored for proteins and peptide delivery and in the field of nutraceuticals and develop pilot plant scale up studies to investigate them in industrial set up.

Synthesis of hybrid polymer blend nanoparticles and incorporation into in situ gel foam spray for controlled release therapy using a versatile synthetic purine nucleoside analogue antiviral drug

Antiviral drug loaded nanoparticles is incorporated intoin situgel for controlled release therapy. Chemical and physical interactions of drug and polymers in the system influenced their characteristics and drug release mechanism.

Engineered nanocrystal technology: in-vivo fate, targeting and applications in drug delivery

Formulation of nanocrystals is a robust approach which can improve delivery of poorly water soluble drugs, a challenge pharmaceutical industry has been facing since long. Large scale production of nanocrystals is done by techniques like precipitation, media milling and, high pressure homogenization. Application of appropriate stabilizers along with drying accords long term stability and commercial viability to nanocrystals. These can be administered through oral, parenteral, pulmonary, dermal and ocular routes showing their high therapeutic applicability. They serve to target drug molecules in specific regions through size manipulation and surface modification. This review dwells upon the in-vivo fate and varying applications in addition to the facets of drug nanocrystals stated above.