Lipid-Based Nanocarriers as Topical Drug Delivery Systems for Intraocular Diseases

Liposomal topical drug administration surpasses alternative methods in glaucoma therapeutics: a novel paradigm for enhanced treatment

OBJECTIVES

Glaucoma is a leading cause of permanent blindness. Despite therapeutic advancements, glaucoma management remains challenging due to limitations of conventional drug delivery, primarily topical eye drops, resulting in suboptimal outcomes and a global surge in cases. To address these issues, liposomal drug delivery has emerged as a promising approach.

KEY FINDINGS

This review explores the potential of liposomal-based medications, with a particular focus on topical administration as a superior alternative to enhance therapeutic efficacy and improve patient compliance compared to existing treatments. This writing delves into the therapeutic prospects of liposomal formulations across different administration routes, as evidenced by ongoing clinical trials. Additionally, critical aspects of liposomal production and market strategies are discussed herein.

SUMMARY

By overcoming ocular barriers and optimizing drug delivery, liposomal topical administration holds the key to significantly improving glaucoma treatment outcomes.

Anti-biofilm activity of carvacrol-thymoquinone nanocarriers on vulvovaginal candidiasis isolates

Given the recurrent nature of vulvovaginal candidiasis (VVC), the restricted availability of effective antifungal agents, and the recent rise in drug resistance, this study sought to assess the antifungal efficacy of carvacrol-thymoquinone delivered via a nanocarrier on Candida isolates obtained from patients with VVC. Isolates were identified using phenotypic and genotypic methods. Nanocarriers were synthesized using the thin-film hydration method. The antifungal activity of carvacrol-thymoquinone was evaluated using the broth microdilution method (CLSIM27-A3). The impact of nanocarriers on the biofilm formation capabilities of Candida isolates was assessed using the MTT assay. Data were analyzed using the Mann-Whitney U test. The nanocarrier exhibited a spherical morphology with a diameter measuring 50 nm. The nano-formulated drug combination could inhibit biofilm formation in C. albicans at half the minimum inhibitory concentration and in C. glabrata at the minimum inhibitory concentration. Our results suggest that the carvacrol-thymoquinone nanocarrier can be studied further in vivo for potential use in the treatment of recurrent VVC.

Nanocarrier-Based, ocular drug delivery: Challenges, prospects, and the therapeutic landscape in the United Arab Emirates

Human eyes have the most complex and advanced physiological defense barriers. Due to these barriers, efficient delivery of ocular drugs is a major challenge in the treatment of eye diseases and disorders. Posterior eye diseases such as retinopathy are the leading causes of impaired vision and blindness globally. The topical and systemic administration of drugs such as eye drops, ointments, intravitreal injections, intraocular implants, contact lenses, and emulsions are the perennial approaches employed to treat ocular diseases. However, these modalities are inefficient due to the low bioavailability of the active drug and the potential for drug-related cytotoxicity to the ocular tissue. In this review, the conventional approaches in ocular drug delivery systems (DDSs) are explored and the limitations associated with each technique are elucidated. A comparison between the different DDSs is presented, showing the most effective treatment techniques available to date. In addition, this review presents recent advances in the field of nanocarriers and microcarriers used in ocular drug delivery systems such as nanoparticles, nano-suspensions, nanofibers, nanogels, nano-liposomes, nano micelles, dendrimers, contact lens, microneedle, and implants. Further, this review identifies the utility of nano-carriers in enabling the development of new-generation ocular DDSs with low toxicity, high efficiency, and high stability of targeted drug delivery systems to overcome the limitations observed with conventional ocular DDSs. In addition, this manuscript sheds light on the incidence and unique landscape of ocular diseases in the United Arab Emirates (UAE), and the potential for employing novel ocular DDSs for targeted treatment of conditions such as diabetic retinopathy in the UAE. It also discusses the putative role genetic variants of the VEGF gene may play in predisposing the local population in the UAE to developing posterior eye segment diseases such as retinopathy.

Nanomedicine in Ophthalmology: From Bench to Bedside

Ocular diseases such as cataract, refractive error, age-related macular degeneration, glaucoma, and diabetic retinopathy significantly impact vision and quality of life worldwide. Despite advances in conventional treatments, challenges like limited bioavailability, poor patient compliance, and invasive administration methods hinder their effectiveness. Nanomedicine offers a promising solution by enhancing drug delivery to targeted ocular tissues, enabling sustained release, and improving therapeutic outcomes. This review explores the journey of nanomedicine from bench to bedside, focusing on key nanotechnology platforms, preclinical models, and case studies of successful clinical translation. It addresses critical challenges, including pharmacokinetics, regulatory hurdles, and manufacturing scalability, which must be overcome for successful market entry. Additionally, this review highlights safety considerations, current marketed and FDA-approved nanomedicine products, and emerging trends such as gene therapy and personalized approaches. By providing a comprehensive overview of the current landscape and future directions, this article aims to guide researchers, clinicians, and industry stakeholders in advancing the clinical application of nanomedicine in ophthalmology.

Nanotechnological prospective for enhancing the antibacterial activity of mupirocin and cinnamon essential oil: a combination therapy

Backgrounds

The aim of the current study was to develop a distinctive nanolipid formulation, namely, nanostructured lipid carrier (NLC), which would deliver an antibacterial medication such as mupirocin (MP). Additionally, cinnamon essential oil (CEO), which is reported to exhibit antibacterial activity, was utilized in the development process in an attempt to improve the influence of MP.

Methods

As a consequence, different MP-NLC formulations were developed using the central composite design (CCD) approach. One optimized formula was selected and incorporated within the pre-formulated gel matrix, providing the MP-NLC-gel formula for efficient topical application. MP-NLC-gel was assessed for its physical characteristics to check its suitability for topical application and evaluated for its in vitro drug release over 6 h. Furthermore, it studied the formulation for its stability at different conditions; 25°C ± 2°C and at 4°C ± 3°C for 6 months. Finally, the formulation was examined for its antibacterial performance against gram-positive and -negative bacteria.

Results

The developed topical NLC-gel formulation demonstrated pH 5.8, viscosity 14,510 cP, and spreadability 58.1 mm, which were seemed to be satisfactory properties for successful topical application. The drug was released successfully for over 6 h with 52.9%. Additionally, it was stable in both storage conditions for 6 months since it displayed non-significant variations in its evaluated characteristics compared to those of fresh preparation. Ultimately, the developed gel formulation could inhibit the growth of different bacterial strains, especially gram-negative strains.

Conclusion

To sum up, these findings would demonstrate the efficiency of NLC prepared with CEO and incorporating MP to be a promising antibacterial lipid nanocarrier.

Exploring Hydrogel Nanoparticle Systems for Enhanced Ocular Drug Delivery

Drug delivery to the ocular system is affected by anatomical factors like the corneal epithelium, blinking reflex, aqueous blood barrier, and retinal blood barrier, which lead to quick removal from the site and inefficient drug delivery. Developing a drug delivery mechanism that targets specific eye tissue is a major hurdle for researchers. Our study examines the challenges of drug absorption in these pathways. Hydrogels have been researched as a suitable delivery method to overcome some obstacles. These are developed alone or in conjunction with other technologies, such as nanoparticles. Many polymer hydrogel nanoparticle systems utilizing both natural and synthetic polymers have been created and investigated; each has pros and cons. The complex release mechanism of encapsulated agents from hydrogel nanoparticles depends on three key factors: hydrogel matrix swelling, drug-matrix chemical interactions, and drug diffusion. This mechanism exists regardless of the type of polymer. This study provides an overview of the classification of hydrogels, release mechanisms, and the role of controlled release systems in pharmaceutical applications. Additionally, it highlights the integration of nanotechnology in ocular disease therapy, focusing on different types of nanoparticles, including nanosuspensions, nanoemulsions, and pharmaceutical nanoparticles. Finally, the review discusses current commercial formulations for ocular drug delivery and recent advancements in non-invasive techniques. The objective is to present a comprehensive overview of the possibilities for enhancing ocular medication delivery through hydrogel nanoparticle systems.

Recent advances and strategies for nanocarrier-mediated topical therapy and theranostic for posterior eye disease

Posterior eye disorders, such as age-related macular degeneration, diabetic retinopathy, and glaucoma, have a significant impact on human quality of life and are the primary cause of age-related retinal diseases among adults. There is a pressing need for innovative topical approaches to treat posterior eye disorders, as current methods often rely on invasive procedures with inherent risks. Limited success was attained in the realm of topical ophthalmic delivery through non-invasive means. Additionally, there exists a dearth of literature that delves into the potential of this approach for drug delivery and theranostic purposes, or that offers comprehensive design strategies for nanocarrier developers to surmount the significant physiological ocular barriers. This review offers a thorough and up-to-date state-of-the-art overview of 40 studies on therapeutic loaded nanocarriers and theranostic devices that, to the best of our knowledge, represent all successful works that reached posterior eye segments through a topical non-invasive administration. Most importantly, based on the successful literature studies, this review provides a comprehensive summary of the potential design strategies that can be implemented during nanocarrier development to overcome each ocular barrier.

Engineered therapeutic proteins for sustained-release drug delivery systems

Proteins play a vital role in diverse biological processes in the human body, and protein therapeutics have been applied to treat different diseases such as cancers, genetic disorders, autoimmunity, and inflammation. Protein therapeutics have demonstrated their advantages, such as specific pharmaceutical effects, low toxicity, and strong solubility. However, several disadvantages arise in clinical applications, including short half-life, immunogenicity, and low permeation, leading to reduced drug effectiveness. The structure of protein therapeutics can be modified to increase molecular size, leading to prolonged stability and increased plasma half-life. Notably, the controlled-release delivery systems for the sustained release of protein drugs and preserving the stability of cargo proteins are envisioned as a potential approach to overcome these challenges. In this review, we summarize recent research progress related to structural modifications (PEGylation, glycosylation, poly amino acid modification, and molecular biology-based strategies) and promising long-term delivery systems, such as polymer-based systems (injectable gel/implants, microparticles, nanoparticles, micro/nanogels, functional polymers), lipid-based systems (liposomes, solid lipid nanoparticles, nanostructured lipid carriers), and inorganic nanoparticles exploited for protein therapeutics. STATEMENT OF SIGNIFICANCE: In this review, we highlight recent advances concerning modifying proteins directly to enhance their stability and functionality and discuss state-of-the-art methods for the delivery and controlled long-term release of active protein therapeutics to their target site. In terms of drug modifications, four widely used strategies, including PEGylation, poly amino acid modification, glycosylation, and genetic, are discussed. As for drug delivery systems, we emphasize recent progress relating to polymer-based systems, lipid-based systems developed, and inorganic nanoparticles for protein sustained-release delivery. This review points out the areas requiring focused research attention before the full potential of protein therapeutics for human health and disease can be realized.

Trends in Formulation Approaches for Sustained Drug Delivery to the Posterior Segment of the Eye

The eye, an intricate organ comprising physical and physiological barriers, poses a significant challenge for ophthalmic physicians seeking to treat serious ocular diseases affecting the posterior segment, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Despite extensive efforts, the delivery of therapeutic drugs to the rear part of the eye remains an unresolved issue. This comprehensive review delves into conventional and innovative formulation strategies for drug delivery to the posterior segment of the eye. By utilizing alternative nanoformulation approaches such as liposomes, nanoparticles, and microneedle patches, researchers and clinicians can overcome the limitations of conventional eye drops and achieve more effective drug delivery to the posterior segment of the eye. These innovative strategies offer improved drug penetration, prolonged residence time, and controlled release, enhancing therapeutic outcomes for ocular diseases. Moreover, this article explores recently approved delivery systems that leverage diverse polymer technologies, such as chitosan and hyaluronic acid, to regulate drug-controlled release over an extended period. By offering a comprehensive understanding of the available formulation strategies, this review aims to empower researchers and clinicians in their pursuit of developing highly effective treatments for posterior-segment ocular diseases.

Lipid-based nanocarriers challenging the ocular biological barriers: Current paradigm and future perspectives

Eye is the most specialized and sensory body organ and treating eye diseases efficiently is necessary. Despite various attempts, the design of a consummate ophthalmic drug delivery system remains unsolved because of anatomical and physiological barriers that hinder drug transport into the desired ocular tissues. It is important to advance new platforms to manage ocular disorders, whether they exist in the anterior or posterior cavities. Nanotechnology has piqued the interest of formulation scientists because of its capability to augment ocular bioavailability, control drug release, and minimize inefficacious drug absorption, with special attention to lipid-based nanocarriers (LBNs) because of their cellular safety profiles. LBNs have greatly improved medication availability at the targeted ocular site in the required concentration while causing minimal adverse effects on the eye tissues. Nevertheless, the exact mechanisms by which lipid-based nanocarriers can bypass different ocular barriers are still unclear and have not been discussed. Thus, to bridge this gap, the current work aims to highlight the applications of LBNs in the ocular drug delivery exploring the different ocular barriers and the mechanisms viz. adhesion, fusion, endocytosis, and lipid exchange, through which these platforms can overcome the barrier characteristics challenges.

Cannabidiol nanoemulsion for eye treatment - Anti-inflammatory, wound healing activity and its bioavailability using in vitro human corneal substitute

Cannabidiol (CBD) is the non-psychoactive component of the plant Cannabis sativa (L.) that has great anti-inflammatory benefits and wound healing effects. However, its high lipophilicity, chemical instability, and extensive metabolism impair its bioavailability and clinical use. Here, we report on the preparation of a human cornea substitute in vitro and validate this substitute for the evaluation of drug penetration. CBD nanoemulsion was developed and evaluated for stability and biological activity. The physicochemical properties of CBD nanoemulsion were maintained during storage for 90 days under room conditions. In the scratch assay, nanoformulation showed significantly ameliorated wound closure rates compared to the control and pure CBD. Due to the lower cytotoxicity of nanoformulated CBD, a higher anti-inflammatory activity was demonstrated. Neither nanoemulsion nor pure CBD can penetrate the cornea after the four-hour apical treatment. For nanoemulsion, 94 % of the initial amount of CBD remained in the apical compartment while only 54 % of the original amount of pure CBD was detected in the apical medium, and 7 % in the cornea, the rest was most likely metabolized. In summary, the nanoemulsion developed in this study enhanced the stability and biological activity of CBD.

The Evolution of Triamcinolone Acetonide Therapeutic Use in Retinal Diseases: From Off-Label Intravitreal Injection to Advanced Nano-Drug Delivery Systems

Ophthalmic drug delivery to the posterior segment of the eye has been challenging due to the complex ocular anatomy. Intravitreal injection of drugs was introduced to deliver therapeutic doses in the posterior segment. Different posterior segment diseases including age-related macular degeneration, diabetic macular edema, retinal vein occlusions, uveitis, and cystoid macular edema, among others, have been historically treated with intravitreal corticosteroids injections, and more recently with intravitreal corticosteroids drug implants. Triamcinolone acetonide (TA) is the most frequently used intraocular synthetic corticosteroid. Using nanoparticle-based TA delivery systems has been proposed as an alternative to intravitreal injections in the treatment of posterior segment diseases. From these novel delivery systems, topical liposomes have been the most promising strategy. This review is oriented to exhibit triamcinolone acetonide drug evolution and its results in treating posterior segment diseases using diverse delivery platforms.

Development of a Self-Assembled Hydrogels Based on Carboxymethyl Chitosan and Oxidized Hyaluronic Acid Containing Tanshinone Extract Nanocrystals for Enhanced Dissolution and Acne Treatment

This study aimed to construct a pH-responsive nanocrystalline hydrogel drug delivery system for topical delivery of insoluble drugs based on the self-assembly behavior of carboxymethyl chitosan (CMC) and oxidized hyaluronic acid (OHA). The tanshinone nanocrystal (TNCs) extract was prepared by dielectric milling method, the type and ratio of stabilizer of the drug were investigated to optimize the prescription, and the effector surface method was used to optimize the preparation process. OHA was prepared by the sodium periodate oxidation method, and the concentration of CMC and OHA was optimized using gel formation time as an indicator. OHA was dissolved in TNCs and self-assembled with CMC solution to form tanshinone extract nanocrystal hydrogels (CMC-OHA/TNCs), of which the physicochemical properties and in vitro antibacterial activity were evaluated. Results showed that the optimized prescription and process could produce tanshinone extract nanocrystals with a particle size of (223.67 ± 4.03) nm and a polydispersity index (PDI) of 0.2173 ± 0.0008. According to SEM and XRD results, TNCs were completely wrapped in the hydrogel as nanoparticles, and the crystallinity of TNCs was reduced and the diffraction peaks in CMC-OHA/TNCs almost disappeared. In vitro, transdermal test results showed that CMC-OHA/TNCs could release the drug continuously at the acne lesions. The cell-counting kit-8 (CCK-8) assay confirmed that the CMC-OHA/TNCs had no obvious cytotoxicity. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CMC-OHA/TNCs against Propionibacterium acnes and Staphylococcus aureus were significantly lower and the diameter of the inhibition circle was obviously higher than that of TNCs and tanshinone extract crude suspension. This study demonstrated that CMC-OHA/TNCs was a promising delivery system for topical delivery of insoluble drugs, which could improve the solubility of tanshinone extract and enhance its in vitro bacterial inhibitory activity.

Nutraceuticals: A Promising Therapeutic Approach in Ophthalmology

Oxidative stress represents one of the main factors driving the pathophysiology of multiple ophthalmic conditions including presbyopia, cataracts, dry eye disease (DED), glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Currently, different studies have demonstrated the role of orally administered nutraceuticals in these diseases. For instance, they have demonstrated to improve lens accommodation in presbyopia, reduce protein aggregation in cataracts, ameliorate tear film stability, break up time, and tear production in dry eye, and participate in the avoidance of retinal neuronal damage and a decrease in intraocular pressure in glaucoma, contribute to the delayed progression of AMD, or in the prevention or treatment of neuronal death in diabetic retinopathy. In this review, we summarized the nutraceuticals which have presented a positive impact in ocular disorders, emphasizing the clinical assays. The characteristics of the different types of nutraceuticals are specified along with the nutraceutical concentration used to achieve a therapeutic outcome in ocular diseases.

Shea Butter Potentiates the Anti-Bacterial Activity of Fusidic Acid Incorporated into Solid Lipid Nanoparticle

Fusidic acid (FA) is an efficient anti-bacterial drug proven to be efficient against a wide range of bacteria. Nevertheless, the main restriction in its formulation is the limited solubility. To avoid such an obstacle, the drug is incorporated into the lipid core of the nanolipid formulation. Consequently, the present study was an attempt to formulate nanolipid preparation, mainly, solid lipid nanoparticle (SLN) integrating FA. FA-SLN was prepared using shea butter as a lipid phase owing to its reported anti-bacterial activity. Different FA-SLNs were fabricated using the central composite design (CCD) approach. The optimized formula was selected and integrated into a hydrogel base to be efficiently used topically. FA-SLN-hydrogel was evaluated for its character, morphology, in vitro release and stability. The formula was examined for irritation reaction and finally evaluated for its anti-bacterial performance. The optimized formula showed particle size 283.83 nm and entrapment 73.057%. The formulated FA-SLN-hydrogel displayed pH 6.2, viscosity 15,610 cP, spreadability 51.1 mm and in vitro release 64.6% following 180 min. FA-SLN-hydrogel showed good stability for three months at different conditions (room temperature and refrigerator). It exhibited no irritation reaction on the treated rats. Eventually, shea butter displayed a noteworthy effect against bacterial growth that improved the effect of FA. This would indicate prospective anti-bacterial activity of FA when combined with shea butter in SLN formulation as a promising nanocarrier.

The dose-dependent effect of a stabilized cannabidiol nanoemulsion on ocular surface inflammation and intraocular pressure

Cannabidiol (CBD) is a phytocannabinoid that has a great clinical therapeutic potential. Few studies have been published on its efficacy in ocular inflammations while its impact on intraocular pressure (IOP), a major risk factor for glaucoma, remains unclear. Moreover, due to its lability and high lipophilicity, its formulation within a prolonged stable topical ophthalmic solution or emulsion able to penetrate the highly selective corneal barrier is challenging. Therefore, various CBD nanoemulsions (NEs) were designed and evaluated for stability in accelerated conditions. Further, the optimal formulation was tested on a murine LPS-induced keratitis inflammation model. Lastly, increasing CBD concentrations were topically applied, for two weeks, on mice eyes, for IOP measurement. CBD NEs exhibited optimal physicochemical characteristics for ocular delivery. A specific antioxidant was required to obtain the stable, final, formulation. In vivo, 0.4 to 1.6% CBD w/v reduced the levels of key inflammatory cytokines, depending on the concentration applied. These concentrations decreased or did not affect the IOP. Our results showed that a well-designed CBD ocular dosage form can be stabilized for an extended shelf life. Furthermore, the significant decrease in inflammatory cytokines levels could be exploited, provided that an adequate therapeutic dosage regimen is identified in humans.

Topical Pirfenidone-Loaded Liposomes Ophthalmic Formulation Reduces Haze Development after Corneal Alkali Burn in Mice

Corneal chemical burns (CCBs) frequently result in corneal fibrosis or haze, an opacity of the cornea that obstructs vision and induces corneal blindness. Diverse strategies have been employed to prevent or reduce CCB-related corneal haze. In this study, we evaluated the physicochemical characteristics and biologic effects of a topical pirfenidone (PFD)-loaded liposomal formulation (PL) on a corneal alkali burn mice model. We found that PL was appropriate for ocular application due to its physiologic tear pH, osmolarity and viscosity suitable for topical ophthalmic use. Regarding its therapeutic activity, PL-treated mice had significantly reduced haze size and density, corneal edema, corneal thickness, and corneal inflammatory infiltration, in contrast to PFD in aqueous solution (p < 0.01). Importantly, the antifibrotic activity of PL (reduction of corneal haze) was associated with modulation of transforming growth factor (TGF)-β and Interleukin (IL)-1β genes. PL suppressed TGF-β expression and restored normal IL-1β expression in corneal tissue more efficiently in contrast to PFD in aqueous solution. In conclusion, PFD showed essential anti-inflammatory and anti-fibrotic effects in the treatment of alkali burns. Noteworthy, a new formulation of PFD-loaded liposomes remarkably improved these effects, standing out as a promising treatment for corneal haze.

Lipid Nanoparticles for the Posterior Eye Segment

This review highlights the application of lipid nanoparticles (Solid Lipid Nanoparticles, Nanostructured Lipid Carriers, or Lipid Drug Conjugates) as effective drug carriers for pathologies affecting the posterior ocular segment. Eye anatomy and the most relevant diseases affecting the posterior segment will be summarized. Moreover, preparation methods and different types and subtypes of lipid nanoparticles will also be reviewed. Lipid nanoparticles used as carriers to deliver drugs to the posterior eye segment as well as their administration routes, pharmaceutical forms and ocular distribution will be discussed emphasizing the different targeting strategies most recently employed for ocular drug delivery.

Nanocubosomal based in situ gel loaded with natamycin for ocular fungal diseases: development, optimization, in-vitro, and in-vivo assessment

Natamycin (NT) is a synthetic broad-spectrum antifungal used in eye drops. However, it has low solubility and high molecular weight, limiting its permeation, and generally causes eye discomfort or irritation when administered. Therefore, the present study aimed to develop an ophthalmic in situ gel formulation with NT-loaded cubosomes to enhance ocular permeation, improve antifungal activity, and prolong the retention time within the eye. The NT-loaded cubosome (NT-Cub) formula was first optimized using an I-optimal design utilizing phytantriol, PolyMulse, and NT as the independent formulation factors and particle size, entrapment efficiency %, and inhibition zone as responses. Phytantriol was found to increase particle size and entrapment efficiency %. Higher levels of PolyMulse slightly increased the inhibition zone whereas a decrease in particle size and EE% was observed. Increasing the NT level initially increased the entrapment efficiency % and inhibition zone. The optimized NT-Cub formulation was converted into an in situ gel system using 1.5% Carbopol 934. The optimum formula showed a pH-sensitive increase in viscosity, favoring prolonged retention in the eye. The in vitro release of NT was found to be 71 ± 4% in simulated tear fluid. The optimum formulation enhanced the ex vivo permeation of NT by 3.3 times compared to a commercial formulation and 5.2 times compared to the NT suspension. The in vivo ocular irritation test proved that the optimum formulation is less irritating than a commercial formulation of NT. This further implies that the developed formulation produces less ocular irritation and can reduce the required frequency of administration.

Nanotechnology for Topical Drug Delivery to the Anterior Segment of the Eye

Topical drug delivery is one of the most challenging aspects of eye therapy. Eye drops are the most prevalent drug form, especially for widely distributed anterior segment eye diseases (cataracts, glaucoma, dry eye syndrome, inflammatory diseases, etc.), because they are convenient and easy to apply by patients. However, conventional drug formulations are usually characterized by short retention time in the tear film, insufficient contact with epithelium, fast elimination, and difficulties in overcoming ocular tissue barriers. Not more than 5% of the total drug dose administered in eye drops reaches the interior ocular tissues. To overcome the ocular drug delivery barriers and improve drug bioavailability, various conventional and novel drug delivery systems have been developed. Among these, nanosize carriers are the most attractive. The review is focused on the different drug carriers, such as synthetic and natural polymers, as well as inorganic carriers, with special attention to nanoparticles and nanomicelles. Studies in vitro and in vivo have demonstrated that new formulations could help to improve the bioavailability of the drugs, provide sustained drug release, enhance and prolong their therapeutic action. Promising results were obtained with drug-loaded nanoparticles included in in situ gel.

Development of Lactoferrin-Loaded Liposomes for the Management of Dry Eye Disease and Ocular Inflammation

Dry eye disease (DED) is a high prevalent multifactorial disease characterized by a lack of homeostasis of the tear film which causes ocular surface inflammation, soreness, and visual disturbance. Conventional ophthalmic treatments present limitations such as low bioavailability and side effects. Lactoferrin (LF) constitutes a promising therapeutic tool, but its poor aqueous stability and high nasolacrimal duct drainage hinder its potential efficacy. In this study, we incorporate lactoferrin into hyaluronic acid coated liposomes by the lipid film method, followed by high pressure homogenization. Pharmacokinetic and pharmacodynamic profiles were evaluated in vitro and ex vivo. Cytotoxicity and ocular tolerance were assayed both in vitro and in vivo using New Zealand rabbits, as well as dry eye and anti-inflammatory treatments. LF loaded liposomes showed an average size of 90 nm, monomodal population, positive surface charge and a high molecular weight protein encapsulation of 53%. Biopharmaceutical behaviour was enhanced by the nanocarrier, and any cytotoxic effect was studied in human corneal epithelial cells. Developed liposomes revealed the ability to reverse dry eye symptoms and possess anti-inflammatory efficacy, without inducing ocular irritation. Hence, lactoferrin loaded liposomes could offer an innovative nanotechnological tool as suitable approach in the treatment of DED.