Cationized hyaluronic acid coated spanlastics for cyclosporine A ocular delivery: Prolonged ocular retention, enhanced corneal permeation and improved tear production

Fostering the unleashing potential of nanocarriers-mediated delivery of ocular therapeutics

Ocular delivery is the most challenging aspect in the field of pharmaceutical research. The major hurdle for the controlled delivery of drugs to the eye includes the physiological static barriers such as the complex layers of the cornea, sclera and retina which restrict the drug from permeating into the anterior and posterior segments of the eye. Recent years have witnessed inventions in the field of conventional and nanocarrier drug delivery which have shown considerable enhancement in delivering small to large molecules across the eye. The dynamic challenges associated with conventional systems include limited drug contact time and inadequate ocular bioavailability resulting from solution drainage, tear turnover, and dilution or lacrimation. To this end, various bioactive-based nanosized carriers including liposomes, ethosomes, niosomes, dendrimer, nanogel, nanofibers, contact lenses, nanoprobes, selenium nanobells, nanosponge, polymeric micelles, silver nanoparticles, and gold nanoparticles among others have been developed to circumvent the limitations associated with the conventional dosage forms. These nanocarriers have been shown to achieve enhanced drug permeation or retention and prolong drug release in the ocular tissue due to their better tissue adherence. The surface charge and the size of nanocarriers (10-1000 nm) are the important key factors to overcome ocular barriers. Various nanocarriers have been shown to deliver active therapeutic molecules including timolol maleate, ampicillin, natamycin, voriconazole, cyclosporine A, dexamethasone, moxifloxacin, and fluconazole among others for the treatment of anterior and posterior eye diseases. Taken together, in a nutshell, this extensive review provides a comprehensive perspective on the numerous facets of ocular drug delivery with a special focus on bioactive nanocarrier-based approaches, including the difficulties and constraints involved in the fabrication of nanocarriers. This also provides the detailed invention, applications, biodistribution and safety-toxicity of nanocarriers-based therapeutcis for the ophthalmic delivery.

Combination of PEGylation and Cationization on Phospholipid-Coated Cyclosporine Nanosuspensions for Enhanced Ocular Drug Delivery

Strong precorneal clearance mechanisms including reflex blink, constant tear drainage, and rapid mucus turnover constitute great challenges for eye drops for effective drug delivery to the ocular epithelium. In this study, cyclosporine A (CsA) for the treatment of dry eye disease (DED) was selected as the model drug. Two strategies, PEGylation for mucus penetration and cationization for potent cellular uptake, were combined to construct a novel CsA nanosuspension (NS@lipid-PEG/CKC) by coating nanoscale drug particles with a mixture of lipids, DSPE-PEG2000, and a cationic surfactant, cetalkonium chloride (CKC). NS@lipid-PEG/CKC with the mean size ∼173 nm and positive zeta potential ∼+40 mV showed promoted mucus penetration, good cytocompatibility, more cellular uptake, and prolonged precorneal retention without obvious ocular irritation. More importantly, NS@lipid-PEG/CKC recovered tear production and goblet cell density more efficiently than the commercial cationic nanoemulsion on a dry eye disease rat model. All results indicated that a combination of PEGylation and cationization might provide a promising strategy to coordinate mucus penetration and cellular uptake for enhanced drug delivery to the ocular epithelium for nanomedicine-based eye drops.

Intranasal Delivery of Carvedilol- and Quercetin-Encapsulated Cationic Nanoliposomes for Cardiovascular Targeting: Formulation and In Vitro and Ex Vivo Studies

Carvedilol (CVD), an adrenoreceptor blocker, is a hydrophobic Biopharmaceutics Classification System class II drug with poor oral bioavailability due to which frequent dosing is essential to attain pharmacological effects. Quercetin (QC), a polyphenolic compound, is a potent natural antioxidant, but its oral dosing is restricted due to poor aqueous solubility and low oral bioavailability. To overcome the common limitations of both drugs and to attain synergistic cardioprotective effects, we formulated CVD- and QC-encapsulated cationic nanoliposomes (NLPs) in situ gel (CVD/QC-L.O.F.) for intranasal administration. We designed CVD- and QC-loaded cationic nanoliposomal (NLPs) in situ gel (CVD/QC-L.O.F.) for intranasal administration. In vitro drug release studies of CVD/QC-L.O.F. (16.25%) exhibited 18.78 ± 0.57% of QC release and 91.38 ± 0.93% of CVD release for 120 h. Ex vivo nasal permeation studies of CVD/QC-L.O.F. demonstrated better permeation of QC (within 96 h), i.e., 75.09% compared to in vitro drug release, whereas CVD permeates within 48 h, indicating the better interaction between cationic NLPs and the negatively charged biological membrane. The developed nasal gel showed a sufficient mucoadhesive property, good spreadability, higher firmness, consistency, and cohesiveness, indicating suitability for membrane application and intranasal administration. CVD-NLPs, QC-NLPs, and CVD/QC-NLPs were evaluated for in vitro cytotoxicity, in vitro ROS-induced cell viability assessment, and a cellular uptake study using H9c2 rat cardiomyocytes. The highest in vitro cellular uptake of CVD/QC-cationic NLPs by H9c2 cells implies the benefit of QC loading within the CVD nanoliposomal carrier system and gives evidence for better interaction of NLPs carrying positive charges with the negatively charged biological cells. The in vitro H2O2-induced oxidative stress cell viability assessment of H9c2 cells established the intracellular antioxidant activity and cardioprotective effect of CVD/QC-cationic NLPs with low cytotoxicity. These findings suggest the potential of cationic NLPs as a suitable drug delivery carrier for CVD and QC combination for the intranasal route in the treatment of various cardiovascular diseases like hypertension, angina pectoris, etc. and for treating neurodegenerative disorders.

Assembly of In-Situ Gel Containing Nano-Spanlastics of an Angiotensin II Inhibitor as a Novel Epitome for Hypertension Management: Factorial Design Optimization, In-vitro Gauging, Pharmacokinetics, and Pharmacodynamics Appraisal

More than 1 billion people worldwide suffer from hypertension; therefore, hypertension management has been categorized as a global health priority. Losartan potassium (LP) is an antihypertensive drug with a limited oral bioavailability of about 33% since it undergoes the initial metabolic cycle. Thus, nasal administration is a unique route to overcome first-pass metabolism. The investigation focused on the potential effects of LP-loaded spanlastic vesicles (SNVs) on LP pharmacodynamics and pharmacokinetic parameters, utilizing a thin-film hydration methodology established on a 3122 full factorial design. Entrapment efficiency (EE%) ranged from 39.8 ± 3.87.8 to 83.8 ± 2.92% for LP-SNVs. Vesicle size (VS) varied from 205.5 ± 6.5.10 to 445.1 ± 13.52 nm, and the percentage of LP released after 8 h (Q8h) ranged from 30.8 ± 3.10 to 68.8 ± 1.45%. LP permeated through the nasal mucosa during 24 h and flocculated from 194.1 ± 4.90 to 435.3 ± 13.53 µg/cm2. After twenty-four hours, the optimal LP-SNVs in-situ gel showed 2.35 times more permeation through the nasal mucosa than the LP solution. It also lowered systolic blood pressure, so it is thought to be better than the reference formulation in terms of pharmacodynamics. The pharmacokinetics studies demonstrated that the intranasal LP-SNVs gel boosted its bioavailability approximately 6.36 times compared to the oral LP solution. Our research showed that intranasal LP-SNVs could be a good nanoplatform because they are well-tolerated and have possible pharmacokinetics and pharmacodynamics.

Vesicular Drug Delivery Systems: Promising Approaches in Ocular Drug Delivery

Ocular drug delivery poses unique challenges due to the complex anatomical and physiological barriers of the eye. Conventional dosage forms often fail to achieve optimal therapeutic outcomes due to poor bioavailability, short retention time, and off-target effects. In recent years, vesicular drug delivery systems have emerged as promising solutions to address these challenges. Vesicular systems, such as liposome, niosome, ethosome, transfersome, and others (bilosome, transethosome, cubosome, proniosome, chitosome, terpesome, phytosome, discome, and spanlastics), offer several advantages for ocular drug delivery. These include improved drug bioavailability, prolonged retention time on the ocular surface, reduced systemic side effects, and protection of drugs from enzymatic degradation and dilution by tears. Moreover, vesicular formulations can be engineered for targeted delivery to specific ocular tissues or cells, enhancing therapeutic efficacy while minimizing off-target effects. They also enable the encapsulation of a wide range of drug molecules, including hydrophilic, hydrophobic, and macromolecular drugs, and the possibility of combination therapy by facilitating the co-delivery of multiple drugs. This review examines vesicular drug delivery systems, their advantages over conventional drug delivery systems, production techniques, and their applications in management of ocular diseases.

Oxymatrine mitigates Aspergillus fumigatus keratitis by suppressing fungal activity and restricting pyroptosis

Fungal keratitis (FK) is a refractory keratitis caused by excessive inflammation and fungal damage. Excessive inflammation can lead to tissue damage and corneal opacity, resulting in a poor prognosis for FK. Oxymatrine (OMT) is a natural alkaloid, which has rich pharmacological effects, such as antioxidant and anti-inflammation. However, its antifungal activity and the mechanism of action in FK have not been elucidated. This study confirmed that OMT suppressed Aspergillus fumigatus growth, biofilm formation, the integrity of fungal cell and conidial adherence. OMT not only effectively reduced corneal fungal load but also inflammation responses. OMT lessened the recruitment of neutrophils and macrophages in FK. In addition, OMT up-regulated the expression of Nrf2 and down-regulated the expression of IL-18, IL-1β, caspase-1, NLRP3 and GSDMD. Pre-treatment with Nrf2 inhibitor up-regulated the expression of IL-1β, IL-18, caspase-1, NLRP3 and GSDMD supressed by OMT. In conclusion, OMT has efficient anti-inflammatory and antifungal effects by suppressing fungal activity and restricting pyroptosis via Nrf2 pathway. OMT is considered as a potential option for the treatment of FK.

Niosome as a promising tool for increasing the effectiveness of anti-inflammatory compounds

Niosomes are drug delivery systems with widespread applications in pharmaceutical research and the cosmetic industry. Niosomes are vesicles of one or more bilayers made of non-ionic surfactants, cholesterol, and charge inducers. Because of their bilayer characteristics, similar to liposomes, niosomes can be loaded with lipophilic and hydrophilic cargos. Therefore, they are more stable and cheaper in preparation than liposomes. They can be classified into four categories according to their sizes and structures, namely small unilamellar vesicles (SUVs), large unilamellar vesicles (LUVs,), multilamellar vesicles (MLVs), and multivesicular vesicles (MVVs). There are many methods for niosome preparation, such as thin-film hydration, solvent injection, and heating method. The current study focuses on the preparation methods and pharmacological effects of niosomes loaded with natural and chemical anti-inflammatory compounds in kinds of literature during the past decade. We found that most research was carried out to load anti-inflammatory agents like non-steroidal anti-inflammatory drugs (NSAIDs) into niosome vesicles. The studies revealed that niosomes could improve anti-inflammatory agents' physicochemical properties, including solubility, cellular uptake, stability, encapsulation, drug release and liberation, efficiency, and oral bioavailability or topical absorption. See also the graphical abstract(Fig. 1).

Cationic microemulsion of voriconazole for the treatment of fungal keratitis: in vitro and in vivo evaluation

Aim: This investigation aimed to develop a voriconazole-loaded chitosan-coated cationic microemulsion (CVME) to treat fungal keratitis. Methods: Microemulsions were prepared using water titration, and the optimized microemulsion was coated with chitosan to prepare CVME. The physicochemical parameters, ocular irritation potential, in vitro antifungal efficacy and in vitro release studies were performed. The in vivo antifungal efficacy study was conducted in a fungal infection-induced rabbit eye model. Results: The developed CVME displayed acceptable physicochemical properties and excellent mucoadhesive behavior and showed a sustained release profile. Ex vivo and in vivo studies concluded that higher permeability and improved antifungal efficacy were observed for CVME than drug suspension (DS). Conclusion: The prepared CVME7 is a viable alternative to treating fungal keratitis with existing approaches.

Spanlastics: a novel elastic drug delivery system with potential applications via multifarious routes of administration

Drug delivery systems (DDS) based on nanocarriers are designed to transport therapeutic agents to specific areas of the body where they are required to exhibit pharmacodynamic effect. These agents rely on an appropriate carrier to protect them from rapid degradation or clearance and enhance their concentration in target tissues. Spanlastics, an elastic, deformable surfactant-based nanovesicles have the potential to be used as a drug delivery vehicle for wide array of drug molecules. Spanlastics are formed by the self-association of non-ionic surfactants and edge activators in an aqueous phase and have gained attention as promising drug carriers due to their biodegradable, biocompatible, and non-immunogenic structure. In recent years, numerous scientific journals have published research articles exploring the potential of spanlastics to serve as a DDS for various types of drugs as they offer targeted delivery and regulated release of the drugs. Following brief introduction to spanlastics, their structure and methods of preparation, this review focuses on the delivery of various drugs using spanlastics as a carrier via various routes viz. topical, transdermal, ototopical, ocular, oral and nasal. Work carried out by various researchers by employing spanlastics as a carrier for enhancing therapeutic activity of different moieties has been discussed in detail.

Tacrolimus-Loaded Cationic Nanoemulsion In-Situ Gel System: In-Vitro Characterization and Performance in a Dry-Eye Rabbit Model

Dry eye disease (DED) is a highly prevalent ocular surface disease that affects life quality and reduces productivity at work. The purpose of this study is to improve the efficacy of tacrolimus (FK506) in the treatment of DED using the special eye surface retention properties of cationic nanoemulsion (CNE) modified by thermosensitive in-situ gel (ISG) (CNE-ISG). The precorneal retention of CNE-ISG containing 0.05% FK506 (50 min) was longer than that of CNE containing 0.05% FK506 (25 min) and commercial suspension containing 0.1% FK506 (Talymus®) (10 min). Successfully modeled dry-eye rabbits were treated with 0.05% CNE-ISG (twice/day), 0.05% CNE and 0.1% suspension (Talymus®) (thrice/day). Schirmer's tear secretion test showed no significant difference between the CNE-ISG group and the healthy group after 5 days of treatment (p > 0.05). The results of a tear ferning test (TFT) showed that the tear-fern-like crystal branches in the CNE-ISG group returned to normal after 5 days of treatment. Histological analysis showed that the number of goblet cells in the CNE-ISG group significantly increased. HET-CAM stimulation test showed that the CNE-ISG group had no ocular irritation. The above results indicated that CNE-ISG might be a promising delivery system and as an effective dosage form was employed for FK506 in the treatment of DED.

Overview of Recent Advances in Nano-Based Ocular Drug Delivery

Ocular diseases profoundly impact patients' vision and overall quality of life globally. However, effective ocular drug delivery presents formidable challenges within clinical pharmacology and biomaterial science, primarily due to the intricate anatomical and physiological barriers unique to the eye. In this comprehensive review, we aim to shed light on the anatomical and physiological features of the eye, emphasizing the natural barriers it presents to drug administration. Our goal is to provide a thorough overview of various characteristics inherent to each nano-based drug delivery system. These encompass nanomicelles, nanoparticles, nanosuspensions, nanoemulsions, microemulsions, nanofibers, dendrimers, liposomes, niosomes, nanowafers, contact lenses, hydrogels, microneedles, and innovative gene therapy approaches employing nano-based ocular delivery techniques. We delve into the biology and methodology of these systems, introducing their clinical applications over the past decade. Furthermore, we discuss the advantages and challenges illuminated by recent studies. While nano-based drug delivery systems for ophthalmic formulations are gaining increasing attention, further research is imperative to address potential safety and toxicity concerns.

Targeting posterior eye infections with colloidal carriers: The case of Ganciclovir

The ocular system, unlike any other human body organ, is a system in which foreign bodies appear quite defenceless in front of the eye. Several infections of the ocular system occur due to various opportunistic conditions. Cytomegalovirus (CMV) is one of the opportunivores that causes several posterior eye infections. Ganciclovir (GCV),9-(2-hydroxy-1-(hydroxymethyl) ethoxymethyl), is aguanine-antiviral agent primarily used to treat CMV diseases. However, the major challenge is of lower bioavailability. Hence, GCV must be dosed repeatedly to enhance drug absorption. but this causes side effects like neutropenia and bone marrow suppression. So, formulators have used alternative formulation strategies such as prodrug formulation and colloidal drug delivery systems. In the prodrug strategy, they attempted to bind various compounds into the parent drug to increase the permeability and bioavailability of GCV. In colloidal drug delivery systems, mucoadhesive microspheres, nanoparticles, Niosome and liposome were employed to extend the drug residence time at the application site. This paper discusses several colloidal carriers combined with GCV to treat opportunistic CMV infection in the posterior ocular system. It reviews the limitations of conventional ocular therapy and explores various novel formulation approaches to improve the ocular bioavailability of GCV in the posterior chamber of the eye.

Implementing Nanovesicles for Boosting the Skin Permeation of Non-steroidal Anti-inflammatory Drugs

The consumption of non-steroidal anti-inflammatory drugs (NSAIDs) have increased lately around the world, as they are considered essential and popular drugs for effective reduction of pain and inflammation. They have analgesic, antipyretic, and anti-inflammatory activities; also, it was reported recently that they protect against various critical disorders like heart attacks and cancer. However, oral use of NSAIDs may cause several pulmonary, gastrointestinal, hepatic, cardiovascular, cerebral, and renal complications. Therefore, topical NSAIDs were recommended as a substitute to oral NSAIDs for the treatment of inflammation and pain. Still, the skin permeation of NSAIDs is considered a challenge, as the skin have an effective barrier function. Therefore, this review investigates various advanced vesicular nanocarriers and their applications through the skin, to augment the topical delivery of NSAIDs through stratum corneum over the conventional systems, enhance their effectiveness, and reduce the unwanted side effects. These innovative systems can manage bioavailability, solubility, stability, safety, and efficacy issues present in conventional systems.

In vitro and in vivo assessment of structural integrity for HPCD complex@Liposome nanocomposites from ocular surface to the posterior segment of the eye

Investigating the structural integrity of carriers in transit from ocular surface to ocular posterior segment is essential for an efficient topical drug delivery system. In this study, dual-carrier hydroxypropyl-β-cyclodextrin complex@Liposome (HPCD@Lip) nanocomposites were developed for the efficient delivery of dexamethasone. Förster Resonance Energy Transfer with near-infrared I fluorescent dyes and in vivo imaging system were used to investigate the structural integrity of HPCD@Lip nanocomposites after crossing Human conjunctival epithelial cells (HConEpiC) monolayer and in ocular tissues. The structural integrity of inner HPCD complexes was monitored for the first time. The results suggested that 23.1 ± 6.4 % of nanocomposites and 41.2 ± 4.3 % of HPCD complexes could cross HConEpiC monolayer with an intact structure at 1 h. 15.3 ± 8.4 % of intact nanocomposites could reach at least sclera and 22.9 ± 1.2 % of intact HPCD complexes could reach choroid-retina after 60 min in vivo, which showed that the dual-carrier drug delivery system could successfully deliver intact cyclodextrin complexes to ocular posterior segment. In conclusion, in vivo assessment of structural integrity of nanocarriers is greatly significant for guiding the rational design, higher drug delivery efficiency and clinical transformation for topical drug delivery system to the posterior segment of the eye.

Recent Advances of Ocular Drug Delivery Systems: Prominence of Ocular Implants for Chronic Eye Diseases

Chronic ocular diseases can seriously impact the eyes and could potentially result in blindness or serious vision loss. According to the most recent data from the WHO, there are more than 2 billion visually impaired people in the world. Therefore, it is pivotal to develop more sophisticated, long-acting drug delivery systems/devices to treat chronic eye conditions. This review covers several drug delivery nanocarriers that can control chronic eye disorders non-invasively. However, most of the developed nanocarriers are still in preclinical or clinical stages. Long-acting drug delivery systems, such as inserts and implants, constitute the majority of the clinically used methods for the treatment of chronic eye diseases due to their steady state release, persistent therapeutic activity, and ability to bypass most ocular barriers. However, implants are considered invasive drug delivery technologies, especially those that are nonbiodegradable. Furthermore, in vitro characterization approaches, although useful, are limited in mimicking or truly representing the in vivo environment. This review focuses on long-acting drug delivery systems (LADDS), particularly implantable drug delivery systems (IDDS), their formulation, methods of characterization, and clinical application for the treatment of eye diseases.

Recent trends and updates on ultradeformable and elastic vesicles in ocular drug delivery

Ocular drug delivery is enigmatic on account of various physiological precorneal barriers that ultimately hinder efficient drug penetration and corneal absorption. Ultradeformable vesicles embody non-ionic surfactants, edge activators and vesicular builders that provide enormous elasticity and deformability. The elastic vesicles can cross the ocular barriers owing to their peculiar squeezability and distorting ability and, thus, establish an infallible shot for ocular delivery. This review provides an overview of the recent advancements and updates of elastic vesicles as effective ocular drug delivery vehicles.

Polymer- and lipid-based nanocarriers for ocular drug delivery: Current status and future perspectives

Ocular diseases seriously affect patients' vision and life quality, with a global morbidity of over 43 million blindness. However, efficient drug delivery to treat ocular diseases, particularly intraocular disorders, remains a huge challenge due to multiple ocular barriers that significantly affect the ultimate therapeutic efficacy of drugs. Recent advances in nanocarrier technology offer a promising opportunity to overcome these barriers by providing enhanced penetration, increased retention, improved solubility, reduced toxicity, prolonged release, and targeted delivery of the loaded drug to the eyes. This review primarily provides an overview of the progress and contemporary applications of nanocarriers, mainly polymer- and lipid-based nanocarriers, in treating various eye diseases, highlighting their value in achieving efficient ocular drug delivery. Additionally, the review covers the ocular barriers and administration routes, as well as the prospective future developments and challenges in the field of nanocarriers for treating ocular diseases.

Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

Engineering Advanced Drug Delivery Systems for Dry Eye: A Review

Dry eye disease (DED) is a widespread and frequently reported multifactorial ocular disease that not only causes ocular discomfort but also damages the cornea and conjunctiva. At present, topical administration is the most common treatment modality for DED. Due to the existence of multiple biological barriers, instilled drugs generally exhibit short action times and poor penetration on the ocular surface. To resolve these issues, several advanced drug delivery systems have been proposed. This review discusses new dosage forms of drugs for the treatment of DED in terms of their characteristics and advantages. Innovative formulations that are currently available in the market and under clinical investigation are elaborated. Meanwhile, their deficiencies are discussed. It is envisioned that the flourishing of advanced drug delivery systems will lead to improved management of DED in the near future.

Hyaluronic acid in the treatment of dry eye disease

Dry eye disease (DED) is a highly prevalent and debilitating condition affecting several hundred million people worldwide. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan commonly used in the treatment of DED. This review aims to critically evaluate the literature on the safety and efficacy of artificial tears containing HA used in DED treatment. Literature searches were conducted in PubMed, including MEDLINE, and in Embase via Ovid with the search term: "(hyaluronic acid OR hyaluronan OR hyaluronate) AND (dry eye OR sicca)". A total of 53 clinical trials are included in this review, including eight placebo-controlled trials. Hyaluronic acid concentrations ranged from 0.1% to 0.4%. Studies lasted up to 3 months. A broad spectrum of DED types and severities was represented in the reviewed literature. No major complications or adverse events were reported. Artificial tears containing 0.1% to 0.4% HA were effective at improving both signs and symptoms of DED. Two major gaps in the literature have been identified: 1. no study investigated the ideal drop frequency for HA-containing eyedrops, and 2. insufficient evidence was presented to recommend any specific HA formulation over another. Future investigations assessing the optimal drop frequency for different concentrations and molecular weights of HA, different drop formulations, including tonicity, and accounting for DED severity and aetiology are essential for an evidence-based, individualized approach to DED treatment.

Biomaterials and Extracellular Vesicle Delivery: Current Status, Applications and Challenges

In this review, we will discuss the current status of extracellular vesicle (EV) delivery via biopolymeric scaffolds for therapeutic applications and the challenges associated with the development of these functionalized scaffolds. EVs are cell-derived membranous structures and are involved in many physiological processes. Naïve and engineered EVs have much therapeutic potential, but proper delivery systems are required to prevent non-specific and off-target effects. Targeted and site-specific delivery using polymeric scaffolds can address these limitations. EV delivery with scaffolds has shown improvements in tissue remodeling, wound healing, bone healing, immunomodulation, and vascular performance. Thus, EV delivery via biopolymeric scaffolds is becoming an increasingly popular approach to tissue engineering. Although there are many types of natural and synthetic biopolymers, the overarching goal for many tissue engineers is to utilize biopolymers to restore defects and function as well as support host regeneration. Functionalizing biopolymers by incorporating EVs works toward this goal. Throughout this review, we will characterize extracellular vesicles, examine various biopolymers as a vehicle for EV delivery for therapeutic purposes, potential mechanisms by which EVs exert their effects, EV delivery for tissue repair and immunomodulation, and the challenges associated with the use of EVs in scaffolds.

Advanced Vesicular Systems for Antifungal Drug Delivery

Fungal infections are considered one of the most serious conditions as their occurrence has increased lately. Fungi like Candida, Fusarium, and Aspergillus species mostly affect immunocompromised patients as they are considered opportunistic pathogens. These infections can be superficial, cutaneous, subcutaneous, or systemic fungal infections that require specific treatment. There is a wide variety of antifungal drugs that can be used to cure fungal infections; however, most of them have many systemic side effects due to their physicochemical characteristics and high toxicity profile. Hence, the current review focuses on various advanced vesicular carriers with high biocompatibility that can encapsulate the antifungal drugs owing to increase their efficacy and limit the undesirable side effects. These advanced systems can manage stability, solubility, bioavailability, safety, and effectiveness issues present in conventional systems.

Spanlastics a Novel Nanovesicular Carrier: Its Potential Application and Emerging Trends in Therapeutic Delivery

Nanotechnology-based drug delivery system has played a very crucial role in overpowering the tasks allied with the conventional dosage form. Spanlastics, an elastic nanovesicle with an ability to carry wide range of drug molecules, make it a potential drug delivery carrier. Spanlastics have extended rising curiosity for diverse sort of route of administration. They can squeeze themselves through the skin pore due to elastic and deformable nature which makes them favorable for transdermal delivery. Spanlastics consist of non-ionic surfactant or blend of surfactants. Many researchers proved that spanlastics have been significantly augment therapeutic efficacy, enhanced drug bioavailability, and reduced drug toxicity. This review summarizes various vesicular systems, composition and structure of spanlastics, advantages of spanlastics over other drug delivery systems, and mechanism of drug penetration through skin. It also gives a brief on different types of drug encapsulated in spanlastics vesicles for the treatment of various diseases.

Development of cyclosporine A nanosuspension: cytotoxicity and permeability on Caco-2 cell lines

Cyclosporine A is a calcineurin inhibitor and is usually used as an immunosuppressant medication. The main purpose of this study is to develop nanosuspension of polypeptide cyclosporine A by using the wet milling method for oral administration. Cell culture studies were also performed with human intestinal Caco-2 cell lines. Hydroxypropyl methylcellulose and sodium dodecyl sulfate were used as stabilizers in nanosuspension. In vitro characterization studies such as Fourier-transform infrared analysis and morphological imaging with scanning electron microscopy have been carried out with obtained cyclosporine A nanosuspension. The particle size, particle size distribution, and zeta potential values of the nanosuspension were measured approximately 400 nm, 0.4, and -25 mV, respectively. The solubility of cyclosporine A was increased 4.5 times in nanosuspension compared to the coarse cyclosporine A powder. As a result of cytotoxicity studies conducted with different concentrations, it was decided to conduct permeability studies at a dose equivalent to 150 µg/mL cyclosporine A. Permeation studies have shown that the nanosuspension increases cyclosporine A transport by 5 and 1.5 times, respectively, compared to coarse powder and commercial product.

Cyclosporine A Nanosuspensions for Ophthalmic Delivery: A Comparative Study between Cationic Nanoparticles and Drug-Core Mucus Penetrating Nanoparticles

The effect of mucin on ocular bioavailability depends on the extent to which it acts as a barrier or retention site. Mucus penetrating particles (MPPs) can evade the mucus entrapment and associated rapid clearance, but cationic nanoparticles have high adhesion to the mucosa. Both formulations can prolong the drug residence time on the surface of the eyes. The purpose of this work is to compare the effects of mucoadhesion of cationic nanoparticles and mucous permeability of MPPs on ocular bioavailability. Cationic nanosuspensions and drug-core MPP nanosuspensions were developed using the anti-solvent precipitation method. The results of X-ray diffraction revealed that CsA was amorphous. In vitro mucoadhesion evaluation demonstrated that cationic nanosuspensions enhanced the interaction with pig mucin about 5.0-6.0 fold compared to drug-core MPP nanosuspensions. A mucus permeation study by the transwell diffusion system showed that the P_app values of drug-core MPP nanosuspensions were 5.0-10.0 times higher than those of cationic nanosuspensions. In vivo ocular bioavailability evaluation of those CsA formulations was conducted in rabbits using a conventional nanosuspension as a comparison. The CsA concentrations in the cornea following the administration of a cationic nanosuspension and a drug-core MPP nanosuspension were 13,641.10 ng/g and 11,436.07 ng/g, respectively, significantly higher than that of the conventional nanosuspension (8310.762 ng/g). The results showed that both the cationic and MPP nanosuspensions were able to deliver CsA to anterior ocular tissues in effective therapeutic concentrations (10-20 μg/g) with topical drop instillation. The cationic nanosuspension could achieve relatively higher bioavailability than the MPP nanosuspension. The cationic nanosuspension would be a promising ocular drug delivery system.

Wettability and contact angle affect precorneal retention and pharmacodynamic behavior of microspheres

In the present study, we describe the development of betaxolol hydrochloride and montmorillonite with ion exchange in a single formulation to create a novel micro-interactive dual-functioning sustained-release delivery system (MIDFDS) for the treatment of glaucoma. Betaxolol hydrochloride molecule was loaded onto the montmorillonite by ion exchange and MIDFDS formation was confirmed by XPS data. MIDFDS showed similar physicochemical properties to those of Betoptic, such as particle size, pH, osmotic pressure, and rheological properties. Nevertheless, the microdialysis and intraocular pressure test revealed better in vivo performance of MIDFDS, such as pharmacokinetics and pharmacodynamics. With regards to wettability, MIDFDS had a larger contact angle (54.66 ± 5.35°) than Betoptic (36.68 ± 1.77°), enabling the MIDFDS (2.93 s) to spread slower on the cornea than Betoptic (2.50 s). Moderate spreading behavior and oppositely charged electrostatic micro-interactions had a comprehensive influence on micro-interactions with the tear film residue, resulting in a longer precorneal retention time. Furthermore, MIDFDS had a significant sustained-release effect, with complete release near the cornea. The dual-functioning sustained-release carrier together with prolonged pre-corneal retention time (80 min) provided sufficiently high drug concentrations in the aqueous humor to achieve a more stable and long-term IOP reduction for 10 h. In addition, cytotoxicity and hemolysis tests showed that MIDFDS had better biocompatibility than Betoptic. The dual-functioning microspheres presented in this study provide the possibility for improved compliance due to low cytotoxicity and hemolysis, which suggests promising clinical implications.

Implementing Spanlastics for Improving the Ocular Delivery of Clotrimazole: In vitro Characterization, Ex vivo Permeability, Microbiological Assessment and In vivo Safety Study

Purpose

The aim of this study was to encapsulate clotrimazole (CLT), an antifungal drug with poor water solubility characteristics, into spanlastics (SPs) to provide a controlled ocular delivery of the drug.

Methods

Span 60 was used in the formulation of SPs with Tween 80, Pluronic F127, or Kolliphor RH40 as an edge activator (EA). The presence of EA offers more elasticity to the membrane of the vesicles which is expected to increase the corneal permeation of CLT. SPs were prepared using ethanol injection method applying 3² complete factorial design to study the effect of formulation variables (ratio of Span 60: EA (w/w) and type of EA) on SPs characteristics (encapsulation efficiency percent (EE%), average vesicle size (VS), polydispersity index (PDI) and zeta potential (ZP)). Design-Expert software was used to determine the optimum formulation for further investigations.

Results

The optimum formulation determined was S1, which contains 20 mg of Tween 80 used as an EA and 80 mg of Span 60. S1 exhibited EE% = 66.54 ± 7.57%, VS = 206.20 ± 4.95 nm, PDI = 0.39 ± 0.00 and ZP = −29.60 ± 0.99 mV. S1 showed highly elastic sphere-shaped vesicles. Furthermore, S1 displayed a sustained release profile and a higher ex vivo permeation across rabbit cornea relative to CLT suspension. Also, S1 revealed superior inhibition of Candida albicans development compared to CLT suspension applying 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction technique. Moreover, in vivo histopathological examination assured the safety of S1 after ophthalmic application in mature male albino rabbits.

Conclusion

Overall, the outcomes revealed the marked efficacy of SPs for ocular delivery of CLT.

Full Factorial Design for Development and Validation of a Stability-Indicating RP-HPLC Method for the Estimation of Timolol Maleate in Surfactant-Based Elastic Nano-Vesicular Systems

A novel isocratic stability-indicating chromatographic method was developed, optimized and validated using Design-Expert® following ICH guidelines for the quantification of Timolol maleate (TM). The intrinsic stability of TM was assessed by force degradation studies, which concluded no extensive degradation except under alkaline and oxidative conditions. TM was quantified accurately in the surfactant-based elastic vesicular system by separating it on Hypersil BDS C8 column using triethylamine in H2O (0.15%v/v; pH 3.0) and acetonitrile (ACN; 65:35%v/v). The influence of variable factors like mobile phase pH, injection volume (μL), flow rate (mL/min) and ACN content (%) on method responses were assessed using a full factorial design. The method was linear between 0.05 and 10 μg/mL with an R2 value of 0.9993. Limit of detection and limit of quantification were found to be 0.90 and 27.2 ng/mL. The method was specific, with recovery in plain drug solution of 89-92% and elastic nanovesicles of 90-93%. The experimental model was significant (P < 0.0001) as indicated by deliberate changes in the method analyzed through analysis of variance. The total drug content in elastic nanovesicles was estimated to be 9.53 ± 0.01 mg/20-mL dispersion and entrapment efficiency was 44.52 ± 0.73%. The developed method was rapid, economic and precise for the quantification of TM in bulk and vesicular system.

Hydrogels as Emerging Materials for Cornea Wound Healing

Hydrogel biomaterials have many favorable characteristics including tuneable mechanical behavior, cytocompatibility, optical properties suitable for regeneration and restoration of the damaged cornea tissue. The cornea is a tissue susceptible to various injuries and traumas with a complicated healing cascade, in which conserving its transparency and integrity is critical. Accordingly, the hydrogels' known properties along with the stimulation of nerve and cell regeneration make them ideal scaffold for corneal tissue engineering. Hydrogels have been used extensively in clinical applications for the repair and replacement of diseased organs. The development and optimizing of novel hydrogels to repair/replace corneal injuries have been the main focus of researches within the last decade. This research aims to critically review in vitro, preclinical, as well as clinical trial studies related to corneal wound healing using hydrogels in the past 10 years, as this is considered as an emerging technology for corneal treatment. Several unique modifications of hydrogels with smart behaviors have undergone early phase clinical trials and showed promising outcomes. Financially, this considers a multibillion dollars industry and with huge interest from medical devices as well as pharmaceutical industries with several products may emerge within the next five years.

Preparation of Nanoparticle-Containing Ring-Implanted Poly(Vinyl Alcohol) Contact Lens for Sustained Release of Hyaluronic Acid

Here, a novel ring-implanted poly vinyl alcohol (PVA) contact lens (CL) is fabricated and evaluated as a therapeutic CL with potential of sustained release of hyaluronic acid (HA). HA is loaded on chitosan (CS) nanoparticles (NPs) and then the HA-loaded NPs are dispersed in a ring shape PVA hydrogel which is implanted in the final PVA CL. Results show that HA is successfully loaded on NPs (520 ± 18 nm) with loading efficacy of 87% and loading capacity of 50%. The CL hydrogel has a 275% swelling ratio, no degradation during 14 days, 97% light transmittance, and desirable rheological stability under physiological shear force. The release data show a sustained release for HA from the ring implanted CL up to 14 days. The cellular study reveals no corneal epithelial cell cytotoxicity and cell attachment on the CL. The study demonstrates the successful application of the ring-implanted CL to sustain the delivery of HA for treating the dry eye syndrome.

Multifunctional nanocomposite eye drops of cyclodextrin complex@layered double hydroxides for relay drug delivery to the posterior segment of the eye

Topical drug delivery system to the posterior segment of the eye is facing many challenges, such as rapid drug elimination, low permeability, and low concentration at the targeted sites. To overcome these challenges, Multifunctional nanocomposite eye drops of dexamethasone-carboxymethyl-β-cyclodextrin@layered double hydroxides-glycylsarcosine (DEX-CM-β-CD@LDH-GS) were developed for relay drug delivery. Herein, our studies demonstrated that DEX-CM-β-CD@LDH-GS could penetrate through human conjunctival epithelial cells with an intact structure and exhibited integrity in the sclera of rabbits' eyes with in vivo fluorescence resonance energy transfer imaging. Consequently, tissue distribution indicated that DEX-CM-β-CD@LDH-GS nanocomposite eye drops could maintain the effective therapeutic concentration of DEX in choroid-retina within 3 h. As a relay drug delivery system, drug-CD@LDH nanocomposites offer an efficient strategy for drug delivery from ocular surface to the posterior segment.

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^®.

PLGA Nanoparticle Platform for Trans-Ocular Barrier to Enhance Drug Delivery: A Comparative Study Based on the Application of Oligosaccharides in the Outer Membrane of Carriers

Purpose

The trans-ocular barrier is a key factor limiting the therapeutic efficacy of triamcinolone acetonide. We developed a poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) surface modified respectively with 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD), chitosan oligosaccharide and trehalose. Determination of the drug/nanoparticles interactions, characterization of the nanoparticles, in vivo ocular compatibility tests, comparisons of their corneal permeability and their pharmacokinetics in aqueous humor were carried out.

Methods

All PLGA NPs were prepared by the single emulsion and evaporation method and the drug-nanoparticle interaction was studied. The physiochemical features and in vitro corneal permeability of NPs were characterized while the aqueous humor pharmacokinetics was performed to evaluate in vivo corneal permeability of NPs. Ocular compatibility of NPs was investigated through Draize and histopathological test.

Results

The PLGA NPs with lactide/glycolide ratio of 50:50 and small particle size (molecular weight 10 kDa) achieved optimal drug release and corneal permeability. Surface modification with different oligosaccharides resulted in uniform particle sizes and similar drug-nanoparticle interactions, although 2-HP-β-CD/PLGA NPs showed the highest entrapment efficiency. In vitro evaluation and aqueous humor pharmacokinetics further revealed that 2-HP-β-CD/PLGA NPs had greater trans-ocular permeation and retention compared to chitosan oligosaccharide/PLGA and trehalose/PLGA NPs. No ocular irritation in vivo was detected after applying modified/unmodified PLGA NPs to rabbit's eyes.

Conclusion

2-HP-β-CD/PLGA NPs are a promising nanoplatform for localized ocular drug delivery through topical administration.

A Novel Eyes Topical Drug Delivery System: CsA-LNC for the Treatment of DED

PURPOSE

The objective of the present work was to prepare safe and effective Ciclosporin A Lipid nanocapsule (CsA-LNC) eye-drops for the treatment of DED.

METHODS

The phase-inversion method was used to prepared different sizes CsA-LNC. CsA biodistribution in ocular after topical administration in rabbits was analyzed by a validated UPLC-MS/MS method. The efficacy of CsA-LNCs (25 nm, 50 nm, 85 nm) was evaluated using the tear breakup time, fluorescein staining, tear production, inflammatory cytokines and histopathology tests. The safety of CsA-LNCs was study by the score of ocular irritation and histological examination study.

RESULTS

CsA-LNCs(20-100 nm) were successfully prepared, An in vivo PK study showed significant improvement of the bioavailability (4.20-fold (25 nm), 2.15-fold (50 nm) and 2.33-fold (85 nm)) in bulbar conjunctiva, and great permeability was observed in the cornea for CsA-LNCs compared with CsA emulsion. An in vivo PD study showed that CsA-LNCs have great efficacy for DED, and the effect was improved over CsA emulsion. CsA-LNCs were safe and not cause significant irritation to the eyes surface of rabbits.

CONCLUSION

This work has demonstrated CsA-LNCs, in particular small sizes CsA-LNC, are safe and effective with promising potential to treat DED. Grapical abstract.

Recent Advances in the Design of Topical Ophthalmic Delivery Systems in the Treatment of Ocular Surface Inflammation and Their Biopharmaceutical Evaluation

Ocular inflammation is one of the most common symptom of eye disorders and diseases. The therapeutic management of this inflammation must be rapid and effective in order to avoid deleterious effects for the eye and the vision. Steroidal (SAID) and non-steroidal (NSAID) anti-inflammatory drugs and immunosuppressive agents have been shown to be effective in treating inflammation of the ocular surface of the eye by topical administration. However, it is well established that the anatomical and physiological ocular barriers are limiting factors for drug penetration. In addition, such drugs are generally characterized by a very low aqueous solubility, resulting in low bioavailability as only 1% to 5% of the applied drug permeates the cornea. The present review gives an updated insight on the conventional formulations used in the treatment of ocular inflammation, i.e., ointments, eye drops, solutions, suspensions, gels, and emulsions, based on the commercial products available on the US, European, and French markets. Additionally, sophisticated formulations and innovative ocular drug delivery systems will be discussed. Promising results are presented with micro- and nanoparticulated systems, or combined strategies with polymers and colloidal systems, which offer a synergy in bioavailability and sustained release. Finally, different tools allowing the physical characterization of all these delivery systems, as well as in vitro, ex vivo, and in vivo evaluations, will be considered with regards to the safety, the tolerance, and the efficiency of the drug products.

Niosomal Drug Delivery Systems for Ocular Disease-Recent Advances and Future Prospects

The eye is a complex organ consisting of several protective barriers and particular defense mechanisms. Since this organ is exposed to various infections, genetic disorders, and visual impairments it is essential to provide necessary drugs through the appropriate delivery routes and vehicles. The topical route of administration, as the most commonly used approach, maybe inefficient due to low drug bioavailability. New generation safe, effective, and targeted drug delivery systems based on nanocarriers have the capability to circumvent limitations associated with the complex anatomy of the eye. Nanotechnology, through various nanoparticles like niosomes, liposomes, micelles, dendrimers, and different polymeric vesicles play an active role in ophthalmology and ocular drug delivery systems. Niosomes, which are nano-vesicles composed of non-ionic surfactants, are emerging nanocarriers in drug delivery applications due to their solution/storage stability and cost-effectiveness. Additionally, they are biocompatible, biodegradable, flexible in structure, and suitable for loading both hydrophobic and hydrophilic drugs. These characteristics make niosomes promising nanocarriers in the treatment of ocular diseases. Hereby, we review niosome based drug delivery approaches in ophthalmology starting with different preparation methods of niosomes, drug loading/release mechanisms, characterization techniques of niosome nanocarriers and eventually successful applications in the treatment of ocular disorders.

Advances in Biodegradable Nano-Sized Polymer-Based Ocular Drug Delivery

The effective delivery of drugs to the eye remains a challenge. The eye has a myriad of defense systems and physiological barriers that leaves ocular drug delivery systems with low bioavailability profiles. This is mainly due to poor permeability through the epithelia and rapid clearance from the eye following administration. However, recent advances in both polymeric drug delivery and biomedical nanotechnology have allowed for improvements to be made in the treatment of ocular conditions. The employment of biodegradable polymers in ocular formulations has led to improved retention time, greater bioavailability and controlled release through mucoadhesion to the epithelia in the eye, amongst other beneficial properties. Nanotechnology has been largely investigated for uses in the medical field, ranging from diagnosis of disease to treatment. The nanoscale of these developing drug delivery systems has helped to improve the penetration of drugs through the various ocular barriers, thus improving bioavailability. This review will highlight the physiological barriers encountered in the eye, current conventional treatment methods as well as how polymeric drug delivery and nanotechnology can be employed to optimize drug penetration to both the anterior and posterior segment of the eye.