Corneal permeation properties of a charged lipid nanoparticle carrier containing dexamethasone

Formulation, optimization and evaluation of ocular gel containing nebivolol Hcl-loaded ultradeformable spanlastics nanovesicles: In vitro and in vivo studies

The study aims to improve the ocular delivery of Nebivolol HCL (NBV) belonging to the Biopharmaceutics classification system (BCSII) by using spanlastic nanovesicles (SNVs) for ophthalmic delivery and incorporating them into hydroxypropyl methylcellulose gel with ketorolac tromethamine (KET) as an anti-inflammatory to improve glaucoma complications like Conjunctivitis. SNVs were prepared by ethanol injection technique using span (60) as a surfactant and labrasol as an edge activator (EA). The impact of formulation factors on SNVs properties was investigated using a Box-Behnken design. In vitro evaluations showed that the formulations (F1, F4, and F14), containing Span 60 and labrasol as EA (25%, 50%, and 25%), exhibited high EE% with low PS and high ZP and DI. Additionally, 61.72 ± 0.77%, 58.97 ± 1.44%, and 56.20 ± 2.32% of the NBV amount were released from F1, F4, and F14 after 5 h, compared to 93.94 ± 1.21% released from drug suspension. The selected formula (G1), containing F1 in combination with KET and 2% w/w HPMC, exhibited 76.36 ± 0.90% drug release after 12 h. Ex vivo Confocal laser scanning revealed a high penetration of NBV-SNVs gel that ascertained the results of the in-vitro study. In vivo studies showed a significant decrease in glaucoma compared to drug suspension, and histopathological studies showed improvement in glaucomatous eye retinal atrophy. G1 is considered a promising approach to improving ocular permeability, absorption, and anti-inflammatory activity, providing a safer alternative to current regimens.

Phospholipid free nano-vesicles of Brinzolamide Biopolymer Ocular Insert; design, in vitro and in vivo evaluation

The aim of this work to study the feasibility of using phospholipid free vesicles with positive charge inducer in a slowly dissolving polymer ocular insert to successfully control intraocular pressure (IOP) for an extended period. Brinzolamide (BRNZ) was chosen as a model drug and a full factorial design was assembled to investigate the drug loading effect, ratio of cholesterol to fatty moiety and the type of the fatty moiety used on the vesicle size and entrapment efficiency. Linear regression models were constructed, and optimization of the formulation compositions yielded two formulae with palmitic acid as a negatively charged vesicles and cetrimide positively charged vesicles. Both formulae were studied in term of permeation efficiency through bovine corneal membranes. Positively charged vesicles although it didn't achieve the highest flux and cumulative amount permeated per unit surface area in the experiment time course, it achieved the highest retention of drug inside the corneal tissue, so it was chosen to be incorporated in a slowly dissolving polymer ocular insert. The insert was evaluated in term content, physical evaluation, and release properties. In vivo evaluation of the casted ocular inserts was conducted in male albino rabbits against market eye drop product and IOP readings were collected for 48 hours. The positively charged sterosomes containing BRNZ and formulated in polymer ocular inserts achieved extended control of IOP of the test animals compared to the market product.

Steroidal nanoformulations for the treatment of uveitis: potential, promises and future perspectives

BACKGROUND

Intraocular inflammation, commonly referred to as uveitis, is a prevalent ocular disease. The categorization of uveitis may be based on the prevailing anatomical site, which includes anterior, intermediate, and posterior uveitis. There exists a significant body of evidence indicating that T cells play a pivotal role in the pathogenesis of autoimmune uveitis. In addition to the presence of T cells, an elevation in levels of inflammatory cytokines and a reduction in regulatory cytokines were also noted. The primary pharmacological interventions for uveitis comprise of corticosteroids, methotrexate, anti-vascular endothelial growth factor (VEGF) agents, anti-tumor necrosis factor-alpha (TNF-α) antibodies, and sirolimus. These medications offer prompt alleviation for inflammation. Nevertheless, prolonged administration of corticosteroids invariably leads to unfavorable adverse reactions. The traditional topical corticosteroids exhibit certain limitations, including inadequate transcorneal permeation and low corneal retention, leading to reduced ocular bioavailability. Consequently, there is a growing inclination towards the creation of innovative steroid drug delivery systems with the aim of reducing the potential for adverse effects, while simultaneously enhancing the drug's corneal permeation and retention.

CONCLUSION

This review is an attempt to compile all the research work done so far in this field and provides a brief overview of the global efforts to develop innovative nanocarrier-based systems for corticosteroids.

Nanostructured Lipid Carriers Mediated Drug Delivery to Posterior Segment of Eye and their In-vivo Successes

BACKGROUND

The disease of the posterior segment of the eye is a major concern worldwide, and it affects more than 300 million people and leads to serious visual deterioration. The current treatment available is invasive and leads to serious eye complications. These shortcomings and patient discomfort lead to poor patient compliance. In the last decade, Nanostructured lipid carriers (NLC) have established a remarkable milestone in the delivery of drug substances to the posterior segment of the eye. Additionally, NLC can reduce the clearance due to adhesive properties which are imparted due to nano-metric size. This attribute might reduce the adverse effects associated with intravitreal therapy and thus enhance therapeutic efficacy, eventually raising patient adherence to therapy. The current review provides an inclusive account of NLC as a carrier to target diseases of the posterior segment of the eye.

OBJECTIVE

The review focuses on the various barrier encountered in the delivery of drugs to the posterior segment of the eye and the detail about the physicochemical property of drug substances that are considered to be suitable candidates for encapsulation to lipid carriers. Therefore, a plethora of literature has been included in this review. The review is an attempt to describe methods adopted for assessing the in-vivo behavior that strengthens the potential of NLC to treat the disease of the posterior segment of the eye.

CONCLUSION

These NLC-based systems have proven to be a promising alternative in place of invasive intravitreal injections with improved patient compliance.

Development of Carvedilol Nanoformulation-Loaded Poloxamer-Based In Situ Gel for the Management of Glaucoma

The objective of the current study was to fabricate a thermosensitive in situ gelling system for the ocular delivery of carvedilol-loaded spanlastics (CRV-SPLs). In situ gel formulations were prepared using poloxamer analogs by a cold method and was further laden with carvedilol-loaded spanlastics to boost the precorneal retention of the drug. The gelation capacity, rheological characteristics, muco-adhesion force and in vitro release of various in situ gel formulations (CS-ISGs) were studied. The optimized formula (F2) obtained at 22% w/v poloxamer 407 and 5% w/v poloxamer 188 was found to have good gelation capacity at body temperature with acceptable muco-adhesion properties, appropriate viscosity at 25 °C that would ease its ocular application, and relatively higher viscosity at 37 °C that promoted prolonged ocular residence of the formulation post eye instillation and displayed a sustained in vitro drug release pattern. Ex vivo transcorneal penetration studies through excised rabbit cornea revealed that F2 elicited a remarkable (p ˂ 0.05) improvement in CRV apparent permeation coefficient (Papp = 6.39 × 10-6 cm/s) compared to plain carvedilol-loaded in situ gel (CRV-ISG; Papp = 2.67 × 10-6 cm/s). Most importantly, in normal rabbits, the optimized formula (F2) resulted in a sustained intraocular pressure reduction and a significant enhancement in the ocular bioavailability of carvedilol, as manifested by a 2-fold increase in the AUC0-6h of CRV in the aqueous humor, compared to plain CRV-ISG formulation. To sum up, the developed thermosensitive in situ gelling system might represent a plausible carrier for ophthalmic drug delivery for better management of glaucoma.

Microfluidics for nano-drug delivery systems: From fundamentals to industrialization

In recent years, owing to the miniaturization of the fluidic environment, microfluidic technology offers unique opportunities for the implementation of nano drug delivery systems (NDDSs) production processes. Compared with traditional methods, microfluidics improves the controllability and uniformity of NDDSs. The fast mixing and laminar flow properties achieved in the microchannels can tune the physicochemical properties of NDDSs, including particle size, distribution and morphology, resulting in narrow particle size distribution and high drug-loading capacity. The success of lipid nanoparticles encapsulated mRNA vaccines against coronavirus disease 2019 by microfluidics also confirmed its feasibility for scaling up the preparation of NDDSs via parallelization or numbering-up. In this review, we provide a comprehensive summary of microfluidics-based NDDSs, including the fundamentals of microfluidics, microfluidic synthesis of NDDSs, and their industrialization. The challenges of microfluidics-based NDDSs in the current status and the prospects for future development are also discussed. We believe that this review will provide good guidance for microfluidics-based NDDSs.

Nanocarriers significantly augment the absorption of ocular-delivered drugs: A comparative meta-analysis study

This study presents a meta-analysis that compiles information collected from several studies aiming to prove, by evidence, that nanocarriers out-perform conventional formulations in augmenting the bioavailability of ocular topically administered drugs. Data was further categorized into two subgroups; polymeric-based nanocarriers versus their lipid-based counterparts, as well as, naturally-driven carriers versus synthetically-fabricated ones. After normalization, the pharmacokinetic factor, area under the curve (AUC), was denoted as the "effect" in the conducted study, and the corresponding Forest plots were obtained. Our meta-analysis study confirmed the absorption enhancement effect of loading drugs into nanocarriers as compared to conventional topical ocular dosage forms. Interestingly, no significant differences were recorded between the polymeric and lipidic nanocarriers included in the study, while naturally-driven nanoplatforms were proven superior to the synthetic alternatives.

Travoprost Liquid Nanocrystals: An Innovative Armamentarium for Effective Glaucoma Therapy

To date, the ophthalmic application of liquid crystalline nanostructures (LCNs) has not been thoroughly reconnoitered, yet they have been extensively used. LCNs are primarily made up of glyceryl monooleate (GMO) or phytantriol as a lipid, a stabilizing agent, and a penetration enhancer (PE). For optimization, the D-optimal design was exploited. A characterization using TEM and XRPD was conducted. Optimized LCNs were loaded with the anti-glaucoma drug Travoprost (TRAVO). Ex vivo permeation across the cornea, in vivo pharmacokinetics, and pharmacodynamic studies were performed along with ocular tolerability examinations. Optimized LCNs are constituted of GMO, Tween® 80 as a stabilizer, and either oleic acid or Captex® 8000 as PE at 25 mg each. TRAVO-LNCs, F-1-L and F-3-L, showed particle sizes of 216.20 ± 6.12 and 129.40 ± 11.73 nm, with EE% of 85.30 ± 4.29 and 82.54 ± 7.65%, respectively, revealing the highest drug permeation parameters. The bioavailability of both attained 106.1% and 322.82%, respectively, relative to the market product TRAVATAN®. They exhibited respective intraocular pressure reductions lasting for 48 and 72 h, compared to 36 h for TRAVATAN®. All LCNs exhibited no evidence of ocular injury in comparison to the control eye. The findings revealed the competence of TRAVO-tailored LCNs in glaucoma treatment and suggested the potential application of a novel platform in ocular delivery.

Dexamethasone and Dexamethasone Phosphate: Effect on DMPC Membrane Models

Dexamethasone (Dex) and Dexamethasone phosphate (Dex-P) are synthetic glucocorticoids with high anti-inflammatory and immunosuppressive actions that gained visibility because they reduce the mortality in critical patients with COVID-19 connected to assisted breathing. They have been widely used for the treatment of several diseases and in patients under chronic treatments, thus, it is important to understand their interaction with membranes, the first barrier when these drugs get into the body. Here, the effect of Dex and Dex-P on dimyiristoylphophatidylcholine (DMPC) membranes were studied using Langmuir films and vesicles. Our results indicate that the presence of Dex in DMPC monolayers makes them more compressible and less reflective, induces the appearance of aggregates, and suppresses the Liquid Expanded/Liquid Condensed (LE/LC) phase transition. The phosphorylated drug, Dex-P, also induces the formation of aggregates in DMPC/Dex-P films, but without disturbing the LE/LC phase transition and reflectivity. Insertion experiments demonstrate that Dex induces larger changes in surface pressure than Dex-P, due to its higher hydrophobic character. Both drugs can penetrate membranes at high lipid packings. Vesicle shape fluctuation analysis shows that Dex-P adsorption on GUVs of DMPC decreases membrane deformability. In conclusion, both drugs can penetrate and alter the mechanical properties of DMPC membranes.

Synthesis and Characterization of Nanoparticle-Based Dexamethasone-Polypeptide Conjugates as Potential Intravitreal Delivery Systems

The use of dexamethasone for eye disease treatment is limited by its low solubility, bioavailability, and rapid elimination when applied topically. The covalent conjugation of dexamethasone with polymeric carriers is a promising strategy to overcome existing drawbacks. In this work, amphiphilic polypeptides capable of self-assembly into nanoparticles were proposed as potential delivery systems for intravitreal delivery. The nanoparticles were prepared and characterized using poly(L-glutamic acid-co-D-phenylalanine) and poly(L-lysine-co-D/L-phenylalanine) as well as poly(L-lysine-co-D/L-phenylalanine) covered with heparin. The critical association concentration for the polypeptides obtained was in the 4.2-9.4 μg/mL range. The hydrodynamic size of the formed nanoparticles was between 90 and 210 nm, and they had an index of polydispersity between 0.08 and 0.27 and an absolute zeta-potential value between 20 and 45 mV. The ability of nanoparticles to migrate in the vitreous humor was examined using intact porcine vitreous. Conjugation of DEX with polypeptides was performed by additional succinylation of DEX and activation of carboxyl groups introduced to react with primary amines in polypeptides. The structures of all intermediate and final compounds were verified by ¹H NMR spectroscopy. The amount of conjugated DEX can be varied from 6 to 220 µg/mg of polymer. The hydrodynamic diameter of the nanoparticle-based conjugates was increased to 200-370 nm, depending on the polymer sample and drug loading. The release of DEX from the conjugates due to hydrolysis of the ester bond between DEX and the succinyl moiety was studied both in a buffer medium and a vitreous/buffer mixture (50/50, v/v). As expected, the release in the vitreous medium was faster. However, the release rate could be controlled in the range of 96-192 h by varying the polymer composition. In addition, several mathematical models were used to assess the release profiles and figure out how DEX is released.

Chitosan modified 5-fluorouracil nanostructured lipid carriers for treatment of diabetic retinopathy in rats: A new dimension to an anticancer drug

Diabetic retinopathy (DR) is one of the chronic complications of diabetes. It includes retinal blood vessels' damage. If untreated, it leads to loss of vision. The existing treatment strategies for DR are expensive, invasive, and need expertise during administration. Hence, there is a need to develop a non-invasive topical formulation that can penetrate deep to the posterior segment of retina and treat the damaged retinal vessels. In addition, it should also provide sustained release. In recent years, novel drug delivery systems (NDDS) have been explored for treating DR and found successful. In this study, chitosan (CS) modified 5-Fluorouracil Nanostructured Lipid Carriers (CS-5-FU-NLCs) were prepared by modified melt emulsification-ultrasonication method and optimized by Box-Behnken Design. The size, polydispersity index, zeta potential and entrapment efficiency of CS-5-FU-NLCs were 163.2 ± 2.3 nm, 0.28 ± 1.52, 21.4 ± 0.5 mV and 85.0 ± 0.2 %, respectively. The in vitro drug release and ex vivo permeation study confirmed higher and sustained drug release in CS-5-FU-NLCs as compared to 5-FU solution. HET-CAM Model ensured the non-irritant nature of CS-5-FU-NLCs. In vivo ocular studies of CS-5-FU-NLCs confirmed antiangiogenic effect of 5-FU by CAM model and diabetic retinopathy induced rat model, indicating successful delivery of 5-FU to the retina.

Fabrication of nanostructured lipid carriers ocugel for enhancing Loratadine used in treatment of COVID-19 related symptoms: statistical optimization, in-vitro, ex-vivo, and in-vivo studies evaluation

Loratadine (LORA), is a topical antihistamine utilized in the treatment of ocular symptoms of COVID-19. The study aimed to develop a Loratadine Nanostructured Lipid Carriers Ocugel (LORA-NLCs Ocugel), enhance its solubility, trans-corneal penetrability, and bioavailability. full-factorial design was established with 2⁴ trials to investigate the impact of several variables upon NLCs properties. LORA-NLCs were fabricated by using hot melt emulsification combined with high-speed stirring and ultrasonication methods. All obtained formulae were assessed in terms of percent of entrapment efficiency (EE%), size of the particle (PS), zeta potential (ZP), as well as in-vitro release. Via using Design Expert® software the optimum formula was selected, characterized using FTIR, Raman spectroscopy, and stability studies. Gel-based of optimized LORA-NLCs was prepared using 4% HPMC k100m which was further evaluated in terms of physicochemical properties, Ex-vivo, and In-vivo studies. The optimized LORA-NLCs, comprising Compritol 888 ATO^®, Labrasol^®, and Span^® 60 showed EE% of 95.78 ± 0.67%, PS of 156.11 ± 0.54 nm, ZP of -40.10 ± 0.55 Mv, and Qh6% of 99.67 ± 1.09%, respectively. Additionally, it illustrated a spherical morphology and compatibility of LORA with other excipients. Consequently, gel-based on optimized LORA-NLCs showed pH (7.11 ± 0.52), drug content (98.62%± 1.31%), viscosity 2736 cp, and Q12% (90.49 ± 1.32%). LORA-NLCs and LORA-NLCs Ocugel exhibited higher ex-vivo trans-corneal penetrability compared with the aqueous drug dispersion. Confocal laser scanning showed valuable penetration of fluoro-labeled optimized formula and LORA-NLCs Ocugel through corneal. The optimized formula was subjected to an ocular irritation test (Draize Test) that showed the absence of any signs of inflammation in rabbits, and histological analysis showed no effect or damage to rabbit eyeballs. C_max and the AUC_0-24 were higher in LORA-NLCs Ocugel compared with pure Lora dispersion-loaded gel The research findings confirmed that NLCs could enhance solubility, trans-corneal penetrability, and the bioavailability of LORA.

Development of a Luliconazole Nanoemulsion as a Prospective Ophthalmic Delivery System for the Treatment of Fungal Keratitis: In Vitro and In Vivo Evaluation

Luliconazole (LCZ), a novel imidazole drug, has broad-spectrum and potential antifungal effects, which makes it a possible cure for fungal keratitis; nevertheless, its medical use in ocular infections is hindered by its poor solubility. The purpose of this study was to design and optimize LCZ nanoemulsion (LCZ-NE) formulations using the central composite design-response surface methodology, and to investigate its potential in improving bioavailability following ocular topical administration. The LCZ-NE formulation was composed of Capryol 90, ethoxylated hydrogenated castor oil, Transcutol^® P and water. The shape of LCZ-NE was spherical and uniform, with a droplet size of 18.43 ± 0.05 nm and a low polydispersity index (0.070 ± 0.008). The results of an in vitro release of LCZ study demonstrated that the LCZ-NE released more drug than an LCZ suspension (LCZ-Susp). Increases in the inhibition zone indicated that the in vitro antifungal activity of the LCZ-NE was significantly improved. An ocular irritation evaluation in rabbits showed that the LCZ-NE had a good tolerance in rabbit eyes. Ocular pharmacokinetics analysis revealed improved bioavailability in whole eye tissues that were treated with LCZ-NE, compared with those treated with LCZ-Susp. In conclusion, the optimized LCZ-NE formulation exhibited excellent physicochemical properties, good tolerance, enhanced antifungal activity and bioavailability in eyes. This formulation would be safe, and shows promise in effectively treating ocular fungal infections.

Ciprofloxacin-Loaded Zein/Hyaluronic Acid Nanoparticles for Ocular Mucosa Delivery

Bacterial conjunctivitis is a worldwide problem that, if untreated, can lead to severe complications, such as visual impairment and blindness. Topical administration of ciprofloxacin is one of the most common treatments for this infection; however, topical therapeutic delivery to the eye is quite challenging. To tackle this, nanomedicine presents several advantages compared to conventional ophthalmic dosage forms. Herein, the flash nanoprecipitation technique was applied to produce zein and hyaluronic acid nanoparticles loaded with ciprofloxacin (ZeinCPX_HA NPs). ZeinCPX_HA NPs exhibited a hydrodynamic diameter of <200 nm and polydispersity index of <0.3, suitable for ocular drug delivery. In addition, the freeze-drying of the nanoparticles was achieved by using mannitol as a cryoprotectant, allowing their resuspension in water without modifying the physicochemical properties. Moreover, the biocompatibility of nanoparticles was confirmed by in vitro assays. Furthermore, a high encapsulation efficiency was achieved, and a release profile with an initial burst was followed by a prolonged release of ciprofloxacin up to 24 h. Overall, the obtained results suggest ZeinCPX_HA NPs as an alternative to the common topical dosage forms available on the market to treat conjunctivitis.

Dexamethasone: Insights into Pharmacological Aspects, Therapeutic Mechanisms, and Delivery Systems

Dexamethasone (DEX) has been widely used to treat a variety of diseases, including autoimmune diseases, allergies, ocular disorders, cancer, and, more recently, COVID-19. However, DEX usage is often restricted in the clinic due to its poor water solubility. When administered through a systemic route, it can elicit severe side effects, such as hypertension, peptic ulcers, hyperglycemia, and hydro-electrolytic disorders. There is currently much interest in developing efficient DEX-loaded nanoformulations that ameliorate adverse disease effects inhibiting advancements in scientific research. Various nanoparticles have been developed to selectively deliver drugs without destroying healthy cells or organs in recent years. In the present review, we have summarized some of the most attractive applications of DEX-loaded delivery systems, including liposomes, polymers, hydrogels, nanofibers, silica, calcium phosphate, and hydroxyapatite. This review provides our readers with a broad spectrum of nanomedicine approaches to deliver DEX safely.

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.

Co-Delivery of Dexamethasone and Captopril by α8 Integrin Antibodies Modified Liposome-PLGA Nanoparticle Hybrids for Targeted Anti-Inflammatory/Anti-Fibrosis Therapy of Glomerulonephritis

Purpose

Mesangial cells-mediated glomerulonephritis refers to a category of immunologically mediated glomerular injuries characterized by infiltration of circulating inflammatory cells, proliferation of mesangial cells, and the common pathological manifestation to the later stage is renal fibrosis, accompanied by excessive accumulation of extracellular matrix (ECM). Treatment regimens include glucocorticoids and immunosuppressive agents, but their off-target distribution causes severe systemic toxicity. Hence, specific co-delivery of “anti-inflammatory/anti-fibrosis” drugs to the glomerular mesangial cell (MC) region is expected to produce better therapeutic effects.

Methods

A novel kidney-targeted nanocarrier drug delivery system targeting MCs was constructed using passive targeting resulting from the difference in pore size between the glomerular endothelial layer and the basement membrane, and active targeting based on the specific binding of antibodies and antigens. Specifically, a liposome-nanoparticle hybrid (PLGA-LNHy) was formed by coating the surface of PLGA nanoparticles (NPs) with a phospholipid bilayer, and then PLGA-LNHy was co-modified with PEG and α8 integrin antibodies to obtain PLGA immunoliposomes (PLGA-ILs).

Results

The results showed that the obtained NPs had a core-shell structure, uniform and suitable particle size (119.1 ± 2.31 nm), low cytotoxicity, and good mesangial cell-entry ability, which can successfully accumulate in the glomerular MC region. Both dexamethasone (DXMS) and captopril (CAP) were loaded onto PLGA-ILs with a drug loading of 10.22 ± 1.00% for DXMS and 6.37 ± 0.25% for CAP (DXMS/CAP@PLGA-ILs). In vivo pharmacodynamics showed that DXMS/CAP@PLGA-ILs can effectively improve the pathological changes in the mesangial area and positive expression of proliferating cell nuclear antigen (PCNA) in glomeruli as well as reduce the expression of inflammatory factors, fibrotic factors and reactive oxygen species (ROS). Thus, renal inflammation and fibrosis were relieved.

Conclusion

We have provided a strategy to increase nanoparticle accumulation in MCs with the potential to implement regulatory effects of anti-inflammatory and anti-fibrosis in glomerulonephritis (GN).

Improving the solubility of vorinostat using cyclodextrin inclusion complexes: The physicochemical characteristics, corneal permeability and ocular pharmacokinetics of the drug after topical application

Vorinostat (suberoylanilide hydroxamic acid, SAHA), an FDA-approved drug for cutaneous T cell lymphoma, has antiangiogenic and anti-inflammatory activity and thus has therapeutic potential for inflammatory corneal neovascularization (CNV). However, its practical administration is limited due to its poor aqueous solubility and permeability. This study aimed to enhance the corneal permeability of SAHA by promoting its inclusion into a complex with hydroxypropyl-β-CD (HPβCD) for topical application. In phase-solubility studies, the solubility of SAHA with HPβCD and sulfobutyl ether-β-CD (SEβCD) was assessed at different temperatures, and complexation efficiencies (K) were calculated. The inclusion complexes (ICs) were prepared and characterized by differential scanning calorimetry (DSC), infrared spectrometry (IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) after freeze-drying. The phase-solubility study showed that the complexation efficiencies of SAHA were higher in HPβCD solutions (297.35 M^-1, 115.28 M^-1 and 122.75 M^-1) than in SEβCD solutions (169.75 M^-1, 91.33 M^-1 and 96.49 M^-1) at 4 °C, 25 °C and 37 °C. HPβCD was selected for SAHA-IC preparation, and characterization revealed IC formation. SAHA existed in an amorphous state in the ICs. The ex vivo corneal permeability of SAHA was also evaluated and found to be greater when formulated as an HPβCD solution than as a suspension. Irritation assays in rabbit eyes showed that the SAHA-IC solution was not irritating after topical application. The ocular pharmacokinetics of SAHA in New Zealand White rabbits were assessed following topical administration (0.2%), and a 0.2% SAHA suspension was used as the control. Compared to its formulation as a suspension, the formulation of SAHA as an HPβCD solution increased its corneal bioavailability by more than 3-fold and its conjunctival bioavailability by more than 2-fold. Thus, IC formation was effective at improving the ocular bioavailability of SAHA. This study provides an important alternative approach for developing liquid pharmaceutical formulations of SAHA for topical ocular applications.

Enhanced topical corticosteroids delivery to the eye: A trade-off in strategy choice

Topical corticosteroids are the primary treatment of ocular inflammation caused by surgery, injury, or other conditions. Drug pre-corneal residence time, drug water solubility, and drug corneal permeability coefficient are the major factors that determine the ocular drug bioavailability after topical administration. Although growing research successfully enhanced local delivery of corticosteroids utilizing various strategies, rational and dynamic approaches to strategy selection are still lacking. Within this review, an overview of the various strategies as well as their performance in retention, solubility, and permeability coefficient of corticosteroids are provided. On this basis, the tradeoff of strategy selection is discussed, which may shed light on the rational choice and application of ophthalmic delivery enhancement strategies.

Hyaluronic Acid-Dexamethasone Nanoparticles for Local Adjunct Therapy of Lung Inflammation

The delivery of a dexamethasone formulation directly into the lung appears as an appropriate strategy to strengthen the systemic administration, reducing the dosage in the treatment of lung severe inflammations. For this purpose, a hyaluronic acid-dexamethasone formulation was developed, affording an inhalable reconstituted nanosuspension suitable to be aerosolized. The physico-chemical and biopharmaceutical properties of the formulation were tested: size, stability, loading of the spray-dried dry powder, reconstitution capability upon redispersion in aqueous media. Detailed structural insights on nanoparticles after reconstitution were obtained by light and X-ray scattering techniques. (1) The size of the nanoparticles, around 200 nm, is in the proper range for a possible engulfment by macrophages. (2) Their structure is of the core-shell type, hosting dexamethasone nanocrystals inside and carrying hyaluronic acid chains on the surface. This specific structure allows for nanosuspension stability and provides nanoparticles with muco-inert properties. (3) The nanosuspension can be efficiently aerosolized, allowing for a high drug fraction potentially reaching the deep lung. Thus, this formulation represents a promising tool for the lung administration via nebulization directly in the pipe of ventilators, to be used as such or as adjunct therapy for severe lung inflammation.

Synthesized nanoparticles, biomimetic nanoparticles and extracellular vesicles for treatment of autoimmune disease: Comparison and prospect

An emerging strategy is needed to treat autoimmune diseases, many of which are chronic with no definitive cure. Current treatments only alleviate symptoms and have many side effects affecting patient quality of life. Recently, nanoparticle drug delivery systems, an emerging method in medicine, has been used to target cells or organs, without damaging normal tissue. This approach has led to fewer side effects, along with a strong immunosuppressive capacity. Therefore, a nanotechnology approach may help to improve the treatment of autoimmune diseases. In this review, we separated nanoparticles into three categories: synthesized nanoparticles, biomimetic nanoparticles, and extracellular vesicles. This review firstly compares the typical mechanism of action of these three nanoparticle categories respectively in terms of active targeting, camouflage effect, and similarity to parent cells. Then their immunomodulation properties are discussed. Finally, the challenges faced by all these nanoparticles are described.

Tailoring Terpesomes and Leciplex for the Effective Ocular Conveyance of Moxifloxacin Hydrochloride (Comparative Assessment): In-vitro, Ex-vivo, and In-vivo Evaluation

Aim

To compare the ability of both terpesomes (TPs) and leciplex (LPs) loaded moxifloxacin hydrochloride (MOX) for enhancing ocular drug conveyance.

Methods

Two separate 2¹.3¹ full-factorial trials were established to determine the influence of multiple variables upon nanovesicles properties and select the optimized formulae using Design Expert^® software. The thin-film hydration method was used to formulate TPs, while the single-step procedure was used for LPs. All formulae were characterized for their entrapment efficiency percent (EE%), particle size distribution (PS), polydispersity index (PDI), and zeta potential (ZP). Then, the optimized formulae were selected, evaluated, and compared for additional assessments.

Results

The optimized formulae TP4 and LP1 showed EE% of 84.14±0.21 and 78.47±0.17%, PS of 578.65±5.65 and 102.41±3.39 nm, PDI of 0.56±0.04 and 0.28±0.01, ZP of -12.50±0.30 and 32.50±0.50 mV, respectively. Further, LP1 showed enhanced corneal permeation across cow cornea compared to MOX solution and TP4. Besides, confocal laser scanning microscopy assessment viewed valuable infiltration from the fluoro-labeled LP through corneal layers compared to TP. LP1 showed spherical morphology and, its ability to adhere to mucus membranes was justified. Further, LP1 showed superiority over MOX solution in biofilm inhibition and eradication in addition to the treatment of infected mice with methicillin-resistant Staphylococcus aureus without any inflammatory response. Finally, the histopathological study verified the harmlessness and biocompatibility of the assembled LPs.

Conclusion

The gained outcomes confirmed the capability of utilizing LPs as a successful nanovesicle for the ocular conveyance of MOX over TPs and MOX solution.

Dexamethasone-Loaded Nanostructured Lipid Carriers for the Treatment of Dry Eye Disease

Dry eye disease (DED) or keratoconjunctivitis sicca is a chronic multifactorial disorder of the ocular surface caused by tear film dysfunction. Symptoms include dryness, irritation, discomfort and visual disturbance, and standard treatment includes the use of lubricants and topical steroids. Secondary inflammation plays a prominent role in the development and propagation of this debilitating condition. To address this we have investigated the pilot scale development of an innovative drug delivery system using a dexamethasone-encapsulated cholesterol-Labrafac™ lipophile nanostructured lipid carrier (NLC)-based ophthalmic formulation, which could be developed as an eye drop to treat DED and any associated acute exacerbations. After rapid screening of a range of laboratory scale pre-formulations, the chosen formulation was prepared at pilot scale with a particle size of 19.51 ± 0.5 nm, an encapsulation efficiency of 99.6 ± 0.5%, a PDI of 0.08, and an extended stability of 6 months at 4 °C. This potential ophthalmic formulation was observed to have high tolerability and internalization capacity for human corneal epithelial cells, with similar behavior demonstrated on ex vivo porcine cornea studies, suggesting suitable distribution on the ocular surface. Further, ELISA was used to study the impact of the pilot scale formulation on a range of inflammatory biomarkers. The most successful dexamethasone-loaded NLC showed a 5-fold reduction of TNF-α production over dexamethasone solution alone, with comparable results for MMP-9 and IL-6. The ease of formulation, scalability, performance and biomarker assays suggest that this NLC formulation could be a viable option for the topical treatment of DED.

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.

Formulation and Characterization of Acetazolamide/Carvedilol Niosomal Gel for Glaucoma Treatment: In Vitro, and In Vivo Study

Acetazolamide (ACZ) is a diuretic used in glaucoma treatment; it has many side effects. Carvedilol (CAR) is a non-cardioselective beta-blocker used in the treatment of elevated intraocular pressure; it is subjected to the first-pass metabolism and causes fluids accumulation leading to edema. This study focuses on overcoming previous side effects by using a topical formula of a combination of the two previous drugs. Sixty formulations of niosomes containing Span 20, Span 60, Tween 20, and Tween 60 with two different ratios were prepared and characterized. Formulation with the lowest particle size (416.30 ± 0.23), the highest zeta potential (72.04 ± 0.43 mv), and the highest apparent coefficient of corneal permeability (0.02 ± 0.29 cm/h) were selected. The selected formula was incorporated into the gel using factorial design 2³. Niosomes (acetazolamide/carvedilol) consisting of Span 60 and cholesterol in the molar ratio (7:6), HMPC, and carbopol with two different ratios were used. The selected formula was subjected to an in vivo study of intraocular pressure in ocular hypertensive rabbits for 60 h. The sustained gel formula of the combination decreased (IOP) to normal after 1 h and sustained efficacy for 4 days. Histological analysis of rabbit eyeballs treated with the selected formula showed improvement in glaucomatous eye retinal atrophy.

Smart nano-micro platforms for ophthalmological applications: The state-of-the-art and future perspectives

Smart nano-micro platforms have been extensively applied for diverse biomedical applications, mostly focusing on cancer therapy. In comparison with conventional nanotechnology, the smart nano-micro matrix can exhibit specific response to exogenous or endogenous triggers, and thus can achieve multiple functions e.g. site-specific drug delivery, bio-imaging and detection of bio-molecules. These intriguing techniques have expanded into ophthalmology in recent years, yet few works have been summarized in this field. In this work, we provide the state-of-the-art of diverse nano-micro platforms based on both the conventional materials (e.g. natural or synthetic polymers, lipid nanomaterials, metal and metal oxide nanoparticles) and emerging nanomaterials (e.g. up-conversion nanoparticles, quantum dots and carbon materials) in ophthalmology, with some smart nano/micro platformers highlighted. The common ocular diseases studied in the field of nano-micro systems are firstly introduced, and their therapeutic method and the related drawback in clinic treatment are presented. The recent progress of different materials for diverse ocular applications is then demonstrated, with the representative nano- and micro-systems highlighted in detail. At last, an in-depth discussion on the clinical translation challenges faced in this field and the future direction are provided. This review would allow the researchers to design more smart nanomedicines in a more rational manner for specific ophthalmology applications.

Corneal delivery of moxifloxacin and dexamethasone combination using drug-eluting mucoadhesive contact lens to treat ocular infections

The important causes of loss of vision are ocular infections, including keratitis and conjunctivitis. Attaining an adequate concentration of topically applied antibiotics to prevent or treat infections within the cornea is challenging. The study aimed to design and develop a drug-eluting polymeric contact lens for the effective delivery of moxifloxacin (MF) and dexamethasone (DM). The polymeric contact lens was prepared using chitosan, glycerol, and polyethylene glycol. MF and DM were loaded into the contact lens, both separately and in combination. The MF and DM loaded contact lenses were characterized for thickness, swelling index, surface topography, and mucoadhesion strength. Furthermore, studies were performed to understand the in vitro drug release behavior, ex vivo corneal permeation, and in vitro and in vivo antimicrobial activity. The drug-loaded contact lens was compared with the standard drug solutions. The physical characteristics of the polymeric contact lens were similar to the commercially available contact lens. Compared to the topically applied standard drug solutions, the drug-loaded contact lens showed significantly (p < 0.05) greater corneal drug distribution after 24 h incubation. In vitro and in vivo antimicrobial activity of the MF loaded contact lens was superior to the standard drug solution. In vivo drug distribution studies showed greater tissue concentration of MF in cornea, sclera, and aqueous humor with contact lens application compared with drug solutions. Overall, the polymeric contact lens was efficient in delivering MF and DM at required therapeutic concentrations. The findings from the present study show that drug-eluting contact lenses could be used in post-operative conditions to prevent ocular infections.

Effect of surfactant concentration and sterilization process on intraocular pressure-lowering activity of Δ9-tetrahydrocannabinol-valine-hemisuccinate (NB1111) nanoemulsions

The use of Δ⁹-tetrahydrocannabinol (THC) and Δ⁹-tetrahydrocannabinol-valine-hemisuccinate (THC-VHS; NB1111) has recently been investigated in the management of intraocular pressure (IOP). The current study was undertaken to develop an optimized THC-VHS-loaded nanoemulsion formulation (NE; THC-VHS-NE) that could improve the drug load and duration of activity. THC-VHS-NE formulation was prepared by homogenization followed by ultrasonication. Sesame oil, Tween®80, and Poloxamer®188 were used as the oil, surfactant, and cosurfactant, respectively. Stability of the optimized THC-VHS-NE formulation was observed at 4 °C. The IOP lowering effect of the lead formulations, commercial timolol, and latanoprost ophthalmic solutions, as well as an emulsion in Tocrisolve™ (THC-VHS-TOC), was studied in New Zealand White rabbits following topical administration. The effect of surfactant concentration and sterilization process on IOP-lowering activity was also studied. THC-VHS-NE formulations (0.5, 1.0, and 2.0% w/v) showed dose dependent duration of action. The 1.0%w/v THC-VHS-NE formulation was selected for further evaluation because of its desirable physical and chemical characteristics. THC-VHS-NE formulation prepared with 2% w/v Tween®80 exhibited a higher drop in IOP than the 0.75 and 4.0% w/v of Tween®80 containing formulations. The IOP-lowering duration was, however, similar for the formulations with 0.75 and 2.0% Tween®80, while that with 4.0% Tween®80 was shorter. THC-VHS-NE formulation produced a greater drop in IOP (p < 0.05) and a longer duration of activity compared to THC-VHS-TOC, latanoprost, and timolol. The formulation could be sterilized by filtration without impacting product attributes. Overall, the optimized THC-VHS-NE formulation demonstrated a significantly better IOP reduction profile in the test model compared to the commercial ophthalmic solutions evaluated.

Cutting-edge advances in therapy for the posterior segment of the eye: Solid lipid nanoparticles and nanostructured lipid carriers

Posterior segment eye diseases affect more than 300 million patients worldwide resulting in severe visual impairment. The treatments available are invasive, costly, present irregular effectiveness, and cause serious adverse effects. These drawbacks significantly reduce patient compliance. In the last decade, solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) have shown potential as innovative carriers for lipophilic drug substances to overcome hurdles in treating the eye posterior segment. This review shows the advantages of these formulations, focusing on their compatibility with ocular tissues, which increases the internalization of the drug substances. Additionally, SLN and NLC can reduce the clearance by the eye's protective mechanisms due to adhesive properties related to nanometric size. Therefore, these preparations may allow the treating of several ophthalmic diseases by topical administration, increasing the interval between doses. This feature can decrease adverse effects and enhance efficacy, ultimately improving patient compliance. Thus, this critical review presents the performance of the in vitro, ex vivo, and in vivo assays that support the potential of SLN and NLC to treat diseases of the posterior segment of the eye. These nanoparticles have shown to be promising alternative towards a major shift in developing ophthalmic products.

Evaluation of His6-Metal Assemblies as a Drug Delivery Vehicle in the Treatment of Anterior Segment Disease Using a Corneal Inflammation Model

Keratitis is a common ophthalmological disease and also a common cause of blindness (second only to cataracts). This disease is routinely treated by topical administration of dexamethasone sodium phosphate (Dexp). However, due to the presence of anatomical and physiological barriers, frequent administration is needed, often resulting in poor patient compliance and diverse side effects. In this work, Dexp was in situ encapsulated into a His₆-metal assembly (HmA) to generate Dexp@HmA, which was utilized in the ocular delivery of Dexp. The physicochemical properties of HmA and Dexp@HmA particles were characterized in detail using various techniques such as dynamic light scattering (DLS), scanning electron microscopy (SEM), and UV-vis spectroscopy. Compared to commercial Eudragi and reported PLGA nanoparticles, HmA showed higher encapsulation efficiency (EE%) and higher loading capacity (LC wt %) of Dexp. Dexp@HmA displayed pH-dependent release; after 33 days at pH 5.8, 6.5, and 7.2, 100%, 65%, and 42% of Dexp, respectively, had been released. In addition, HmA and Dexp@HmA showed low cytotoxicity to macrophages and to all common ocular cell types tested. The effect of Dexp@HmA on corneal inflammation was evaluated using in vitro and in vivo models. Our results demonstrate that Dexp@HmA is much superior to free Dexp in both in vitro and in vivo models. These positive results suggest that HmA may represent a promising candidate nanocarrier for the treatment of various diseases of the anterior segment of the eye.

Chitosan and its Derivatives for Ocular Delivery Formulations: Recent Advances and Developments

Chitosan (CS) is a hemi-synthetic cationic linear polysaccharide produced by the deacetylation of chitin. CS is non-toxic, highly biocompatible, and biodegradable, and it has a low immunogenicity. Additionally, CS has inherent antibacterial properties and a mucoadhesive character and can disrupt epithelial tight junctions, thus acting as a permeability enhancer. As such, CS and its derivatives are well-suited for the challenging field of ocular drug delivery. In the present review article, we will discuss the properties of CS that contribute to its successful application in ocular delivery before reviewing the latest advances in the use of CS for the development of novel ophthalmic delivery systems. Colloidal nanocarriers (nanoparticles, micelles, liposomes) will be presented, followed by CS gels and lenses and ocular inserts. Finally, instances of CS coatings, aiming at conferring mucoadhesiveness to other matrixes, will be presented.

Chitosan Derivatives with Mucoadhesive and Antimicrobial Properties for Simultaneous Nanoencapsulation and Extended Ocular Release Formulations of Dexamethasone and Chloramphenicol Drugs

The aim of this work was to evaluate the effectiveness of neat chitosan (CS) and its derivatives with 2-acrylamido-2-methyl-1-propanesulfonic acid (AAMPS) and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSP) as appropriate nanocarriers for the simultaneous ocular administration of dexamethasone sodium phosphate (DxP) and chloramphenicol (CHL). The derivatives CS-AAMPS and CS-MEDSP have been synthesized by free-radical polymerization and their structure has been proved by Fourier-Transformed Infrared Spectroscopy (FT-IR) spectroscopy. Both derivatives exhibited low cytotoxicity, enhanced mucoadhesive properties and antimicrobial activity against Staphylococcus aureus (S.aureus) and Escherichia coli (E. coli). Encapsulation was performed via ionic crosslinking gelation using sodium tripolyphosphate (TPP) as the crosslinking agent. Dynamic light scattering measurements (DLS) showed that the prepared nanoparticles had bimodal distribution and sizes ranging from 50–200 nm and 300–800 nm. Drugs were encapsulated in their crystalline (CHL) or amorphous (DexSP) form inside nanoparticles and their release rate was dependent on the used polymer. The CHL dissolution rate was substantially enhanced compared to the neat drug and the release time was extended up to 7 days. The release rate of DexSP was much faster than that of CHL and was prolonged up to 3 days. Drug release modeling unveiled that diffusion is the main release mechanism for both drugs. Both prepared derivatives and their drug-loaded nanoparticles could be used for extended and simultaneous ocular release formulations of DexSP and CHL drugs.

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.

Fabrication of Transgelosomes for Enhancing the Ocular Delivery of Acetazolamide: Statistical Optimization, In Vitro Characterization, and In Vivo Study

Acetazolamide (ACZ) is a potent carbonic anhydrase inhibitor that is used for the treatment of glaucoma. Its oral administration causes various undesirable side effects. This study aimed to formulate transgelosomes (TGS) for enhancing the ocular delivery of ACZ. ACZ-loaded transfersomes were formulated by the ethanol injection method, using phosphatidylcholine (PC) and different edge activators, including Tween 80, Span 60, and Cremophor RH 40. The effects of the ratio of lipid to surfactant and type of surfactant on % drug released after 8 h (Q_8h) and entrapment efficiency (EE%) were investigated by using Design-Expert software. The optimized formula was formulated as TGS, using poloxamers as gelling agents. In vitro and in vivo characterization of ACZ-loaded TGS was performed. According to optimization study, F8 had the highest desirability value and was chosen as the optimized formula for preparing TGS. F8 appeared as spherical elastic nanovesicles with Q_8h of 93.01 ± 3.76% and EE% of 84.44 ± 2.82. Compared to a free drug, TGS exhibited more prolonged drug release of 71.28 ± 0.46% after 8 h, higher ex vivo permeation of 66.82 ± 1.11% after 8 h and a significant lowering of intraocular pressure (IOP) for 24 h. Therefore, TGS provided a promising technique for improving the corneal delivery of ACZ.

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.

Characterisation of 2-HP-β-cyclodextrin-PLGA nanoparticle complexes for potential use as ocular drug delivery vehicles

Aim: 2-HP-β-cyclodextrin-PLGA nanoparticle complexes were prepared to enhance the aqueous humour delivery of Triamcinolone acetonide.Materials & methods: Drug-loaded 2-HP-β-CD/PLGA nanoparticle complexes prepared by adapting a quasi-emulsion solvent evaporation technique. In vitro drug release, in vitro transcorneal permeation study, histopathological study and in vivo transcorneal penetration of PLGA nanoparticles and 2-HP-β-CD/PLGA nanoparticle complexes were evaluated. Results: Particle size distributions of 2-HP-β-CD/PLGA nanoparticle complexes were 149.4 ± 3.7 nm and presented stable system. Corneal penetration studies revealed steady sustained drug release (First-order); 2-HP-β-CD/PLGA nanoparticle complexes increased ocular bioavailability by increasing dispersion in the tear film and improving drug release. Conclusion: 2-HP-β-CD/PLGA nanoparticle complex formulation is a promising alternative to conventional eye drops.

Advances and limitations of drug delivery systems formulated as eye drops

Topical instillation of eye drops remains the most common and easiest route of ocular drug administration, representing the treatment of choice for many ocular diseases. Nevertheless, low ocular bioavailability of topically applied drug molecules can considerably limit their efficacy. Over the last several decades, numerous drug delivery systems (DDS) have been developed in order to improve drug bioavailability on the ocular surfaces. This review systematically covers the most recent advances of DDS applicable by topical instillation, that have shown better performance in in vivo models compared to standard eye drop formulations. These delivery systems are based on in situ forming gels, nanoparticles and combinations of both. Most of the DDS have been developed using natural or synthetic polymers. Polymers offer many advantageous properties for designing advanced DDS including biocompatibility, gelation properties and/or mucoadhesiveness. However, despite the high number of studies published over the last decade, there are several limitations for clinical translation of DDS. This review article focuses on the recent advances for the development of ocular drug delivery systems. In addtion, the potential challenges for commercialization of new DDS are presented.

Combination of drugs and carriers in drug delivery technology and its development

The development of drug-loading technology will bring new and rapid development to the treatment of diseases. At present, drug delivery by nanoparticles, erythrocyte, and platelet have been studied extensively. Compared with traditional anticancer drugs, nano-drugs have shown many obvious advantages, disease treatment based on nanotechnology will bring a revolution in cancer treatment. Due to its inherent biocompatibility, large drug load and long half-life in the blood circulation, erythrocyte-inspired antibiotics, and some anticancer drugs delivery systems have also entered the clinical trial stage. At present, there are relatively few studies on drug delivery by platelets as carriers. It is necessary to overcome the shortcomings of platelets, such as easy activation, deformation, thrombosis, and difficult preservation. There are many ways to combine drugs with these carriers, and each has its own advantages and disadvantages. It is necessary to seek the best combination scheme to increase drug loading and reduce the damage to therapeutic components to the carriers, so as to bring more mature and reliable methods for the clinical application of drug delivery technology. Several drug-loading technologies and their development were described according to various categories. The combination of drugs and carriers is summarized for better understanding of its practical application.

Transdermal permeability of triamcinolone acetonide lipid nanoparticles

Background

Triamcinolone acetonide (TAA) is an effective and the most commonly used corticosteroid hormone for the treatment of hypertrophic scars (HSs). However, the clinically used dosage has poor tissue permeability and injection safety. By contrast, lipid nanoparticles (LNPs) have the advantage of high affinity for the skin.

Materials and methods

This article describes the preparation of TAA-LNPs using poly(lactic-co-glycolic acid) as a carrier material, which have good biocompatibility and biodegradability. Based on a systematic investigation of its physicochemical properties, a rabbit ear HSs model was established to evaluate the percutaneous permeability of TAA-LNPs in scar tissue in vitro as well as to assess its curative effect and skin irritation.

Results

The results showed that the TAA-LNPs formed uniform and round particles under fluoroscopy and had a complex structure in which a nanoparticle core was surrounded by multiple vesicles. The particles were 232.2±8.2 nm in size, and the complimentary potential was -42.16 mV. The encapsulation efficiency was 85.24%, which is greater than that of other common liposomes and nanoparticles. A test of in vitro scar tissue permeability showed that penetration into scar tissue was twofold and 40-fold higher for TAA-LNPs than for common liposome and commercial suspensions, respectively. The concentration of the absorbed drug effectively inhibited fibroblast proliferation, achieved a therapeutic effect in HSs, and did not stimulate intact or damaged skin.

Conclusion

The preparation of TAA into LNPs for transdermal administration can enhance transdermal permeation performance and the safety of this drug, which is beneficial for the treatment of HSs.

Solutol HS15 based binary mixed micelles with penetration enhancers for augmented corneal delivery of sertaconazole nitrate: optimization, in vitro, ex vivo and in vivo characterization

Keratomycosis is a serious corneal disease that can cause a permanent visual disability if not treated effectively. Sertaconazole nitrate (STZ), a novel broad spectrum antifungal drug, was suggested as a promising treatment. However, its utility in the ocular route is restricted by its poor solubility, along with other problems facing the ocular delivery like short residence time, and the existing corneal barrier. Therefore, the objective of this study was to formulate STZ loaded binary mixed micelles (STZ-MMs) enriched with different penetration enhancers using thin-film hydration method, based on a 3¹.2² mixed factorial design. Different formulation variables were examined, namely, type of auxiliary surfactant, type of penetration enhancer, and total surfactants: drug ratio, and their effects on the solubility of STZ in MMs (S_M), particle size (PS), polydispersity index (PDI), and zeta potential (ZP) were evaluated. STZ-MMs enhanced STZ aqueous solubility up to 338.82-fold compared to free STZ. Two optimized formulations (MM-8 and MM-11) based on the desirability factor (0.891 and 0.866) were selected by Design expert^® software for further investigations. The optimized formulations were imaged by TEM which revealed nanosized spherical micelles. Moreover, they were examined for corneal mucoadhesion, stability upon dilution, storage effect, and ex vivo corneal permeation studies. Finally, both in vivo corneal uptake and in vivo corneal tolerance were investigated. MM-8 showed superiority in the ex vivo and in vivo permeation studies when compared to the STZ-suspension. The obtained results suggest that the aforementioned STZ loaded mixed micellar system could be an effective candidate for Keratomycosis-targeted therapy.

Nanostructured lipid carriers-based thermosensitive eye drops for enhanced, sustained delivery of dexamethasone

AIM

Nanostructured lipid carriers in-gel (NLCs-gel) were prepared to enhance and improve the ocular delivery of dexamethasone. Materials & methods: NLCs containing dexamethasone prepared by high-pressure homogenization were characterized and dispersed into thermosensitive gels (Pluronic F127 and F68 as gels material). In vitro drug release studies, ocular irritation tests, ex vivo corneal penetration and drug dynamics of NLCs and NLCs-gel were evaluated in aqueous humor.

RESULTS

NLCs-gel exhibited a rapid sol-gel transition at 34.4°C and presented nano-sized, narrowly distributed particles. Corneal penetration studies revealed steady sustained drug release (Ritger-Peppas); NLCs-gel increased ocular bioavailability by prolonging precorneal retention time and improving corneal permeation.

CONCLUSION

These findings suggest developing NLCs-gel for potential treatment of posterior segment eye diseases.

Formulation and Characterization of Carvedilol Leciplex for Glaucoma Treatment: In-Vitro, Ex-Vivo and In-Vivo Study

This study evaluated the efficacy of cationic nanoparticle (leciplex) to deliver carvedilol to ocular surface for glaucoma treatment as recent studies pointed out the effect of topical carvedilol on intraocular pressure, therefore carvedilol loaded leciplex formulae were prepared using soy phosphatidyl choline (SPC) and cationic surfactant (CTAB/DDAB) and characterized for morphology, entrapment efficiency, particle size, zeta potential and ex-vivo corneal permeation. Then the selected formula was evaluated via in-vivo studies in comparison with carvedilol solution. Leciplex nanoparticles appeared spherical in shape with entrapment efficiency exceeded 95% in all formulae. Leciplex formula composed of SPC and DDAB in (1:1) molar ratio showed the smallest particle size (16.04 ± 1.2 nm), highest zeta potential value (53.9 ± 0.91 mv) and highest apparent corneal permeability coefficient (0.1157 cm/h). Carvedilol leciplex reduced intraocular pressure (IOP) to normal range in ocular hypertensive rabbits after 30 min and duration of action lasted for 24 h, while carvedilol solution reduced IOP to normal value after 60 min and duration of action lasted for 6 h. Furthermore, histological examination of eyeballs of rabbits treated with carvedilol leciplex showed improvement of retinal atrophy of glaucomatous eyes. This study concluded that leciplex improve transcorneal permeation and bioavailability of carvedilol.

A potential nanoparticle-loaded in situ gel for enhanced and sustained ophthalmic delivery of dexamethasone

Increasing the permeability of drugs across the cornea is key to improving drug absorption by the eye. This study presents a newly developed in situ gel loaded with nanoparticles, which could achieve controlled drug release and high ocular drug bioavailability by avoiding rapid precorneal clearance. The physicochemical parameters of the formulation were investigated and showed uniform size, physical stability, and favorable rheological and gelling properties. Ex vivo permeation studies revealed significantly higher drug release from the in situ gel loaded with nanoparticles compared to the conventional poloxamer in situ gel and the drug solution. When compared with a marketed formulation, the in situ gel loaded with nanoparticles provided slower controlled release and higher ocular bioavailability of dexamethasone. In conclusion, the developed nanoparticle-loaded in situ gel can successfully increase drug ocular bioavailability by enhancing contact time with the ocular surface and permeation through the cornea.