Self-Assembling Colloidal System for the Ocular Administration of Cyclosporine A

Block copolymer micelles as ocular drug delivery systems

Block copolymer micelles, formed by the self-assembly of amphiphilic polymers, address formulation challenges, such as poor drug solubility and permeability. These micelles offer advantages including a smaller size, easier preparation, sterilization, and superior solubilization, compared with other nanocarriers. Preclinical studies have shown promising results, advancing them toward clinical trials. Their mucoadhesive properties enhance and prolong contact with the ocular surface, and their small size allows deeper penetration through tissues, such as the cornea. Additionally, copolymeric micelles improve the solubility and stability of hydrophobic drugs, sustain drug release, and allow for surface modifications to enhance biocompatibility. Despite these benefits, long-term stability remains a challenge. In this review, we highlight the preclinical performance, structural frameworks, preparation techniques, physicochemical properties, current developments, and prospects of block copolymer micelles as ocular drug delivery systems.

Drug repurposing for cancer therapy

Cancer, a complex and multifactorial disease, presents a significant challenge to global health. Despite significant advances in surgical, radiotherapeutic and immunological approaches, which have improved cancer treatment outcomes, drug therapy continues to serve as a key therapeutic strategy. However, the clinical efficacy of drug therapy is often constrained by drug resistance and severe toxic side effects, and thus there remains a critical need to develop novel cancer therapeutics. One promising strategy that has received widespread attention in recent years is drug repurposing: the identification of new applications for existing, clinically approved drugs. Drug repurposing possesses several inherent advantages in the context of cancer treatment since repurposed drugs are typically cost-effective, proven to be safe, and can significantly expedite the drug development process due to their already established safety profiles. In light of this, the present review offers a comprehensive overview of the various methods employed in drug repurposing, specifically focusing on the repurposing of drugs to treat cancer. We describe the antitumor properties of candidate drugs, and discuss in detail how they target both the hallmarks of cancer in tumor cells and the surrounding tumor microenvironment. In addition, we examine the innovative strategy of integrating drug repurposing with nanotechnology to enhance topical drug delivery. We also emphasize the critical role that repurposed drugs can play when used as part of a combination therapy regimen. To conclude, we outline the challenges associated with repurposing drugs and consider the future prospects of these repurposed drugs transitioning into clinical application.

Cyclosporine A micellar nasal spray characterization and antiviral action against SARS-CoV-2

The upper airways represent the point of entrance from where Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection spreads to the lungs. In the present work, α-tocopheryl-polyethylene-glycol succinate (TPGS) micelles loaded with cyclosporine A (CSA) were developed for nasal administration to prevent or treat the viral infection in the very first phases. The behavior of the micelles in presence of simulated nasal mucus was investigated in terms of stability and mucopenetration rate, evidencing long-term stability and fast diffusion across the glycoproteins matrix. Moreover, the spray characteristics of the micellar formulation and deposition profile in a silicon nasal model were studied using three nasal spray devices. Results allowed to identify the nasal spray pump (BiVax, Aptar) able to provide the wider and uniform deposition of the nasal cavity. The cyclosporine A micelles antiviral activity against SARS-CoV-2 was tested on the Omicron BA.1 variant using Vero E6 cells with protocols simulating treatment before, during and after the infection of the upper airways. Complete viral inactivation was observed for the cyclosporine-loaded micelles while a very low activity was evidenced for the non-formulated drug, suggesting a synergistic activity of the drug and the formulation. In conclusion, this work showed that the developed cyclosporine A-loaded micellar formulations have the potential to be clinically effective against a wide spectrum of coronavirus variants.

Construction of intelligent drug delivery system based on polysaccharide-derived polymer micelles: A review

Micelles are nanostructures developed via the spontaneous assembly of amphiphilic polymers in aqueous systems, which possess the advantages of high drug stability or active-ingredient solubilization, targeted transport, controlled release, high bioactivity, and stability. Polysaccharides have excellent water solubility, biocompatibility, and degradability, and can be modified to achieve a hydrophobic core to encapsulate hydrophobic drugs, improve drug biocompatibility, and achieve regulated delivery of the loaded drug. Micelles drug delivery systems based on polysaccharides and their derivatives show great potential in the biomedical field. This review discusses the principles of self-assembly of amphiphilic polymers and the formation of micelles; the preparation of amphiphilic polysaccharides is described in detail, and an overview of common polysaccharides and their modifications is provided. We focus on the review of strategies for encapsulating drugs in polysaccharide-derived polymer micelles (PDPMs) and building intelligent drug delivery systems. This review provides new research directions that will help promote future research and development of PDPMs in the field of drug carriers.

In Vitro and Ex Vivo Models for Assessing Drug Permeation across the Cornea

Drug permeation across the cornea remains a major challenge due to its unique and complex anatomy and physiology. Static barriers such as the different layers of the cornea, as well as dynamic aspects such as the constant renewal of the tear film and the presence of the mucin layer together with efflux pumps, all present unique challenges for effective ophthalmic drug delivery. To overcome some of the current ophthalmic drug limitations, the identification and testing of novel drug formulations such as liposomes, nanoemulsions, and nanoparticles began to be considered and widely explored. In the early stages of corneal drug development reliable in vitro and ex vivo alternatives, are required, to be in line with the principles of the 3Rs (Replacement, Reduction, and Refinement), with such methods being in addition faster and more ethical alternatives to in vivo studies. The ocular field remains limited to a handful of predictive models for ophthalmic drug permeation. In vitro cell culture models are increasingly used when it comes to transcorneal permeation studies. Ex vivo models using excised animal tissue such as porcine eyes are the model of choice to study corneal permeation and promising advancements have been reported over the years. Interspecies characteristics must be considered in detail when using such models. This review updates the current knowledge about in vitro and ex vivo corneal permeability models and evaluates their advantages and limitations.

Polymeric micelles and cancer therapy: an ingenious multimodal tumor-targeted drug delivery system

Since the beginning of pharmaceutical research, drug delivery methods have been an integral part of it. Polymeric micelles (PMs) have emerged as multifunctional nanoparticles in the current technological era of nanocarriers, and they have shown promise in a range of scientific fields. They can alter the release profile of integrated pharmacological substances and concentrate them in the target zone due to their improved permeability and retention, making them more suitable for poorly soluble medicines. With their ability to deliver poorly soluble chemotherapeutic drugs, PMs have garnered considerable interest in cancer. As a result of their remarkable biocompatibility, improved permeability, and minimal toxicity to healthy cells, while also their capacity to solubilize a wide range of drugs in their micellar core, PMs are expected to be a successful treatment option for cancer therapy in the future. Their nano-size enables them to accumulate in the tumor microenvironment (TME) via the enhanced permeability and retention (EPR) effect. In this review, our major aim is to focus primarily on the stellar applications of PMs in the field of cancer therapeutics along with its mechanism of action and its latest advancements in drug and gene delivery (DNA/siRNA) for cancer, using various therapeutic strategies such as crossing blood-brain barrier, gene therapy, photothermal therapy (PTT), and immunotherapy. Furthermore, PMs can be employed as "smart drug carriers," allowing them to target specific cancer sites using a variety of stimuli (endogenous and exogenous), which improve the specificity and efficacy of micelle-based targeted drug delivery. All the many types of stimulants, as well as how the complex of PM and various anticancer drugs react to it, and their pharmacodynamics are also reviewed here. In conclusion, commercializing engineered micelle nanoparticles (MNPs) for application in therapy and imaging can be considered as a potential approach to improve the therapeutic index of anticancer drugs. Furthermore, PM has stimulated intense interest in research and clinical practice, and in light of this, we have also highlighted a few PMs that have previously been approved for therapeutic use, while the majority are still being studied in clinical trials for various cancer therapies.

Posaconazole micelles for ocular delivery: in vitro permeation, ocular irritation and antifungal activity studies

Posaconazole (PSC) is a triazole group anti-fungal agent with the widest spectrum. Although there is no commercially available ocular dosage form, its diluted oral suspension preparation (Noxafil®) is used as off-label in topical treatment of severe keratitis and sclerokeratitis in the clinic. However, ocular bioavailability of PSC suspension form is extremely low due to its highly lipophilic character. Thus, there is a clinical need to improve its ocular bioavailability and to develop novel delivery system for the treatment of ocular fungal infections. Herein, we studied ex vivo permeation, penetration, anti-fungal activity, and Hen's Egg Test-Chorioallantoic Membrane (HET-CAM) toxicity tests in order to assess ocular targeting of PSC micelles, which were optimized in our previous study. The results indicated that micellar carrier system increased the permeability of PSC to eye tissues. Micelles showed higher affinity to ocular tissues than that of commercial oral suspension of PSC (Noxafil®). In vitro anti-fungal activity data also confirmed the efficacy of PSC loaded micellar formulations against Candida. albicans strains. The relative safety of the optimized micelles on the ocular tissue was shown with the HET-CAM toxicity test. In conclusion, micellar systems could be a promising strategy for the effective and safe delivery of PSC in the treatment of ocular fungal infections.

Nanotechnology: revolutionizing the delivery of drugs to treat age-related macular degeneration

Introduction: Age-related macular degeneration (AMD) is a progressive retinal disease that degrades the eye's ability to grasp visual acuity. The antivascular endothelial growth factor (VEGF) therapies have made significant strides in improving the quality of life, and there is a continued opportunity to improve delivery, outcomes, and patient convenience and compliance. The treatments available could gain better clinical outcome from novel therapeutics through nanotechnology application.Areas covered: This review summarizes AMD biology and the pathophysiology of the disease along with the successes and limitations of available therapies. It further discusses the promising nanotechnology modalities that could become the cornerstone of future AMD research for improving delivery and reducing frequency of administration thus, enabling development of novel therapeutics.Expert opinion: The robust translation from preclinical work to clinical outcome for AMD remains an unmet need. Continuing to investigate in deeper understanding of biology and advancing high-quality targets into the clinic in combination with the application of advanced nanotechnology to design patient-centric offerings for both dry and wet AMD is needed. Because of the lack of regulatory precedence, and challenging manufacturing and supply chain need, the future of nano-enabled technologies is challenging but presents exciting treatment options for AMD.

Combination of Nanomicellar Technology and In Situ Gelling Polymer as Ocular Drug Delivery System (ODDS) for Cyclosporine-A

A combination of in situ gelling systems and a loaded drug self-assembling nanomicellar carrier was chosen in this study as a new potential Ocular Drug Delivery System (ODDS) for Cyclosporine-A (CyA), a poorly water-soluble drug. Two non-ionic surfactants (d-α-tocopherol polyethylene glycol succinate, VitE-TPGS and polyoxyl 40 hydrogenated castor oil, RH-40) were used to produce the nanomicelles. The physical-chemical characterization of the nanomicelles in terms of CyA entrapment (EE%) and loading efficiency (LE%), cloud point (CP), regeneration time (RT), size and polydispersity index (PI) allowed us to select the best combination of surfactant mixture, which showed appropriate stability, high CyA-EE (99.07%), very small and homogeneous dimensions and favored the solubilization of an amount of CyA (0.144% w/w) comparable to that contained in marketed emulsion Ikervis^®. The selected nanomicellar formulation incorporated into optimized ion-sensitive polymeric dispersions of gellan gum (GG-LA: 0.10, 0.15 and 0.20% w/w) able to trigger the sol-gel transition after instillation was characterized from technological (osmolality, pH, gelling capacity, rheological behavior, wettability, TEM and storage stability at 4 and 20 °C) and biopharmaceutical points of view. This new combined approach allowed us to obtain clear aqueous dispersions that were easy to instill and able to form a viscous gel when in contact with the tear fluid, improving CyA ocular bioavailability. Furthermore, this new ODDS prevented CyA transcorneal permeation, exhibited low cytotoxicity and prolonged the CyA resident time in the precorneal area compared to Ikervis^®.

Prodrugs and nanomicelles to overcome ocular barriers for drug penetration

INTRODUCTION

Ocular barriers hinder drug delivery and reduce drug bioavailability. This article focuses on enhancing drug absorption across the corneal and conjunctival epithelium. Both, transporter targeted prodrug formulations and nanomicellar strategy is proven to enhance the drug permeation of therapeutic agents across various ocular barriers. These strategies can increase aqueous drug solubility and stability of many hydrophobic drugs for topical ophthalmic formulations.

AREAS COVERED

The article discusses various ocular barriers, ocular influx, and efflux transporters. It elaborates various prodrug strategies used for enhancing drug absorption. Along with this, the article also describes nanomicellar formulation, its characteristic and advantages, and applications in for anterior and posterior segment drug delivery.

EXPERT OPINION

Prodrugs and nanomicellar formulations provide an effective strategy for improving drug absorption and drug bioavailability across various ocular barriers. It will be exciting to see the efficacy of nanomicelles for treating back of the eye disorders after their topical application. This is considered as a holy grail of ocular drug delivery due to the dynamic and static ocular barriers, restricting posterior entry of topically applied drug formulations.

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.

Micelles: Promising Ocular Drug Carriers for Anterior and Posterior Segment Diseases

Micelles have been studied in the targeting of drug substances to different tissues as a nano-sized delivery system for many years. Sustained drug release, ease of production, increased solubility, and bioavailability of drugs with low water solubility are the most important superiorites of micellar carriers. These advantages paved the way for the use of micelles as a drug delivery system in the ocular tissues. The unique anatomical structure of the eye as well as its natural barriers and physiology affect ocular bioavailability of the drugs negatively. Conventional dosage forms can only reach the anterior segment of the eye and are used for the treatment of diseases of this segment. In the treatment of posterior segment diseases, conventional dosage forms are administered sclerally, via an intravitreal injection, or systemically. However, ocular irritation, low patient compliance, and high side effects are also observed. Micellar ocular drug delivery systems have significant promise for the treatment of ocular diseases. The potential of micellar systems ocular drug delivery has been demonstrated by in vivo animal experiments and clinical studies, and they are continuing extensively. In this review, the recent research studies, in which the positive outcomes of micelles for ocular targeting of drugs for both anterior and posterior segment diseases as well as glaucoma has been demonstrated by in vitro, ex vivo, or in vivo studies, are highlighted.

Whole-Eye Perfusion Model for Screening of the Ocular Formulations via Confocal Laser Scanning Microscopy

Various physiological, anatomical barriers make ocular drug delivery very challenging. Hence, better in vitro screening models are needed for rapid screening of the formulations. In this study, a simple whole-eye perfusion model was designed and its application was explored for screening targeted formulation across the full-thickness cornea using confocal laser scanning microscopy. PEG-cholecalciferol-based integrin targeted coumarin-6 micelles (TC6M) and non-targeted coumarin-6 micelles (NTC6M) were developed by solvent diffusion evaporation technique. The formulations NTC6M and TC6M had particles size 23.5 ± 5 nm and 28.5 ± 6 nm respectively and osmolality of 294-300 mOsml/Kg. The whole-eye perfusion model was developed using porcine eye. TC6M and NTC6M were instilled on the excised porcine eyes as well as in the eyes of NZW rabbits. Corneas were excised from the experimental eyes; coumarin-6 penetration across the corneas was analyzed using confocal microscope. Coumarin-6-loaded micelles had particle size below 50 nm. NTC6M formulations showed penetration to the deeper layers up to 500 μm porcine eyes and up to 50 μm in rabbit corneas. However, TC6M formulations exhibited superior retention, as higher fluorescent intensities were observed in upper layers up to 50 μm depth in the porcine eye and 20 μm depth in rabbit eye. Hence, applicability of whole-eye perfusion model in preliminary screening of the formulations was successfully demonstrated. Whole-eye perfusion model when combined with confocal microscopy has potential to be used as an efficient tool for rapid screening and optimization of various ophthalmic formulations.

Solubilization of Cyclosporine in Topical Ophthalmic Formulations: Preformulation Risk Assessment on a New Solid Form

Owing to the discovery of a less soluble crystalline form (form 2) of cyclosporine (CsA), risks in solubility and physical stability of these formulations need to be revisited. This work focused on understanding the solubility behavior of various CsA forms in different media, including water, castor oil, and selected cosolvent micellar systems. In water, form 2 was approximately 8-9 times less soluble than form 1 (aka. tetragonal dihydrate). In neat nonaqueous solvent, for example, castor oil, form 3 (aka. orthorhombic hydrate) was found to have the lowest solubility and therefore the most stable form. In addition, the solubility-temperature relationship of CsA is complex and solvent-dependent. In aqueous vehicles, retrograde temperature dependence of solubility was observed in aqueous vehicles, that is, the solubility of CsA decreased with temperature, which was attributed to the effect of temperature on the strength of hydrogen bonding interactions; conversely, the solubility of CsA increased with temperature in nonaqueous solvents. In addition, the solubility of these CsA forms was very sensitive to temperature. Temperature-dependent form transformation was also observed in the media studied, with faster form conversion occurring at elevated temperatures. These studies provided key information to support the risk assessment for topical ophthalmic formulation development of CsA.

Topical application of polymeric nanomicelles in ophthalmology: a review on research efforts for the noninvasive delivery of ocular therapeutics

INTRODUCTION

Polymeric micelles represent nowadays an interesting formulative approach for ocular drug delivery, as they act as solubility enhancers of poorly soluble drugs and promote drug transport across cornea and sclera. In particular, in the last 5 years polymeric nanomicelles have been increasingly investigated to overcome some of the important challenges of the topical treatment of ocular diseases.

AREAS COVERED

The aim of this review was to gather up-to-date information on the different roles that polymeric micelles (commonly in the nanosize scale) can play in ocular delivery. Thus, after a general description of ocular barriers and micelles features, the attention is focused on those properties that are relevant for ophthalmic application. Finally, their efficacy in improving the ocular delivery of different classes of therapeutics (anti-inflammatory, immunosuppressant, antiglaucoma, antifungal, and antiviral drugs) are reported.

EXPERT OPINION

Although still a few, in vivo experiments have clearly demonstrated the capability of polymeric nanomicelles to overcome a variety of hurdles associated to ocular therapy, notably increasing drug bioavailability. However, there are still some very important issues to be solved, such as tolerability and stability; additionally, the role of micelles in drug uptake by the ocular tissues and their potential for the treatment of posterior eye diseases still need to be clarified/verified.

Cyclosporine A delivery to the eye: A comprehensive review of academic and industrial efforts

Local ocular delivery of cyclosporine A (CsA) is the preferred method for CsA delivery as a treatment for ocular inflammatory diseases such as uveitis, corneal healing, vernal keratoconjunctivitis and dry eye disease. However, due to the large molecular weight and hydrophobic nature of CsA and the natural protective mechanisms of the eye, achieving therapeutic levels of CsA in ocular tissues can be difficult. This review gives a comprehensive overview of the current products available to clinicians as well as emerging drug delivery solutions that have been developed at both the academic and industry levels.

Cyclosporine Amicellar delivery system for dry eyes

Background

The objectives of this study were to develop stable cyclosporine A (CsA) ophthalmic micelle solutions for dry-eye syndrome and evaluate their physicochemical properties and therapeutic efficacy.

Materials and methods

CsA-micelle solutions (MS-CsA) were created by a simple method with Cremophor EL, ethanol, and phosphate buffer. We investigated the particle size, pH, and osmolarity. In addition, long-term physical and chemical stability for MS-CsA was observed. To confirm the therapeutic efficacy, tear production in dry eye-induced rabbits was evaluated using the Schirmer tear test (STT). When compared to a commercial product, Restasis, MS-CsA demonstrated improvement in goblet-cell density and conjunctival epithelial morphology, as demonstrated in histological hematoxylin and eosin staining.

Results

MS-CsA had a smaller particle size (average diameter 14–18 nm) and a narrow size distribution. Physicochemical parameters, such as particle size, pH, osmolarity, and remaining CsA concentration were all within the expected range of 60 days. STT scores significantly improved in MS-CsA treated groups (P<0.05) in comparison to those of the Restasis-treated group. The number of goblet cells for rabbit conjunctivas after the administration of MS-CsA was 94.83±8.38, a significantly higher result than the 65.17±11.51 seen with Restasis. The conjunctival epithelial morphology of dry eye-induced rabbits thinned with loss of goblet cells. However, after 5 days of treatment with drug formulations, rabbit conjunctivas recovered epithelia and showed a relative increase in the number of goblet cells.

Conclusion

The results of this study indicate the potential use of a novel MS for the ophthalmic delivery of CsA in treating dry eyes.

Applications of polymer micelles for imaging and drug delivery

Polymeric micelles, self-assembling nano-constructs of amphiphilic copolymers, are widely considered as convenient nano-carriers for a variety of applications, such as diagnostic imaging, and drug and gene delivery. They have demonstrated a variety of favorable properties including biocompatibility, longevity, high stability in vitro and in vivo, capacity to effectively solubilize a variety of poorly soluble drugs, changing the release profile of the incorporated pharmaceutical agents, and the ability to accumulate in the target zone based on the enhanced permeability and retention effect. Moreover, additional functions can be imparted to the micelle-based delivery systems by engineering their surface for specific applications. Various targeting ligands can be attached for cell or intracellular accumulation at a site of interest. Also, the chelation or incorporation of imaging moieties into the micelle structure enables in vivo biodistribution studies. Moreover, pH-, thermo-, ultrasound-, enzyme- and light-sensitive block-copolymers allow for controlled micelle dissociation and triggered drug release in response to the pathological environment-specific stimuli and/or externally applied signals. The combination of these approaches can further improve specificity and efficacy of micelle-based drug delivery to promote the development of smart multifunctional micelles.

Controlled ocular drug delivery with nanomicelles

Many vision threatening ocular diseases such as age-related macular degeneration (AMD), diabetic retinopathy, glaucoma, and proliferative vitreoretinopathy may result in blindness. Ocular drug delivery specifically to the intraocular tissues remains a challenging task due to the presence of various physiological barriers. Nonetheless, recent advancements in the field of nanomicelle-based novel drug delivery system could fulfil these unmet needs. Nanomicelles consists of amphiphilic molecules that self-assemble in aqueous media to form organized supramolecular structures. Micelles can be prepared in various sizes (10-1000 nm) and shapes depending on the molecular weights of the core and corona forming blocks. Nanomicelles have been an attractive carrier for their potential to solubilize hydrophobic molecules in aqueous solution. In addition, small size in nanometer range and highly modifiable surface properties have been reported to be advantageous in ocular drug delivery. In this review, various factors influencing rationale design of nanomicelles formulation and disposition are discussed along with case studies. Despite the progress in the field, influence of various properties of nanomicelles such as size, shape, surface charge, rigidity of structure on ocular disposition need to be studied in further details to develop an efficient nanocarrier system.