Enhanced ocular anti-inflammatory activity of ibuprofen carried by an Eudragit RS100 nanoparticle suspension

Graphene Scaffolds: A Striking Approach to Combat Dermatophytosis

Exclusive physicochemical and biological properties of carbon allotrope graphene have attracted the peer attention of researchers for the synthesis and development of newer topical remedies including films, scaffolds, microspheres, and hydrogels. Here, graphene nanoplatelets (GN) were embedded into a different ratio of polymeric ERL100/ERS100 solution and fabricated in the form of a scaffold through the electrospinning process. FTIR spectra displayed characteristic similar peaks present both in GN and GN-loaded scaffold owing to the compatibility of GN and polymeric mixture. XRD curve revealed a distinct GN peak at nearly 26° whereas from DSC/TGA thermal stability was observed between polymers and graphene nanoplatelets. FESEM images showed ultrathin architecture of GN-loaded scaffold in a range of 280 ± 90 nm. The fabricated scaffold exhibited hydrophilicity (contact angle 48.8 ± 2.8°) and desirable swelling index (646% in skin pH media) which were desired criteria for the scaffold for topical application. In vitro, antifungal activity was conducted through the broth microdilution method against different virulent dermatophytes i.e., Microsporum gypseum, M. canis, M. fulvum, and Trychophyton rubrum. For in vivo evaluation, T. rubrum inoculum was applied on the dorsal surface of each group of Swiss albino mice, and the degree and intensity of mycelial growth or erythema on skin surfaces was visually investigated. The study depicted complete signs of cure after 14 days of application of G3-loaded scaffold on the infected dorsal site. Hence graphene-loaded scaffold represented a possible alternative for the treatment of topical fungal infections caused by dermatophytes.

Immune modulating nanoparticles for the treatment of ocular diseases

Ocular diseases are increasingly influencing people’s quality of life. Complicated inflammatory mechanisms involved in the pathogenic process of ocular diseases make inflammation-targeting treatment a potential therapeutic approach. The limited efficacy of conventional anti-inflammatory therapeutic strategies, caused by various objective factors, such as complex ocular biological barriers, and subjective factors, such as poor compliance, are promoting the development of new therapeutic methods. With the advantages of considerable tissue permeability, a controllable drug release rate, and selective tissue targeting ability, nanoparticles have successfully captured researchers’ attention and have become a research hotspot in treating ocular diseases. This review will focus on the advantages of nanosystems over traditional therapy, the anti-inflammation mechanisms of nanoparticles, and the anti-inflammatory applications of nanoparticles in different ocular diseases (ocular surface diseases, vitreoretinopathy, uveal diseases, glaucoma, and visual pathway diseases). Furthermore, by analyzing the current situation of nanotherapy and the challenges encountered, we hope to inspire new ideas and incentives for designing nanoparticles more consistent with human physiological characteristics to make progress based on conventional treatments. Overall, some progress has been made in nanoparticles for the treatment of ocular diseases, and nanoparticles have rather broad future clinical translation prospects.

The Therapeutic Benefits of Nanoencapsulation in Drug Delivery to the Anterior Segment of the Eye: A Systematic Review

Background: Although numerous nanoparticle formulations have been developed for ocular administration, concerns are being raised about a possible mismatch between potential promises made by the field of nanoparticle research and demonstration of actual therapeutic benefit. Therefore, the primary focus of this present review was to critically assess to what extent nanoencapsulation of ocular drugs improved the therapeutic outcome when treating conditions in the anterior segment of the eye.

Methods: A systematic search was conducted using Medline, PubMed, and Embase databases as well as Google Scholar for published peer-reviewed articles in English focusing on conventional nanoparticles used as drug delivery systems to the anterior segment of the eye in in vivo studies. The major therapeutic outcomes were intraocular pressure, tear secretion, number of polymorphonuclear leucocytes and pupil size. The outcome after encapsulation was compared to the non-encapsulated drug.

Results: From the search, 250 results were retrieved. Thirty-eight studies met the inclusion criteria. Rabbits were used as study subjects in all but one study, and the number of animals ranged from 3 to 10. Coated and uncoated liposomes, lipid-based and polymeric nanoparticles, as well as micelles, were studied, varying in both particle size and surface charge, and encapsulating a total of 24 different drugs, including 6 salts. The majority of the in vivo studies demonstrated some improvement after nanoencapsulation, but the duration of the benefit varied from less than 1 h to more than 20 h. The most common in vitro methods performed in the studies were drug release, transcorneal permeation, and mucin interaction.

Discussion: Nanoparticles that are small and mucoadhesive, often due to positive surface charge, appeared beneficial. Although in vitro assays can unravel more of the hidden and sophisticated interplay between the encapsulated drug and the nanoparticle structure, they suffered from a lack of in vitro—in vivo correlation. Therefore, more research should be focused towards developing predictive in vitro models, allowing rational design and systematic optimization of ocular nanoparticles with minimal animal experimentation.

Development of Eudragit® Nanoparticles for Intranasal Drug Delivery: Preliminary Technological and Toxicological Evaluation

Intranasal administration has assumed in the last years an increasing value as an alternative strategy for the systemic adsorption of drugs, as an alternative to oral and parenteral routes thanks to the high vascularized nasal mucosa. Nevertheless, different drug features may restrict its absorption through the nasal mucosa with an insufficient diffusion to the systemic circulation. Several technological strategies are under investigation to improve drug absorption during nasal formulation design and production. The use of bioadhesive polymers can be considered a valid approach to pursue the aforementioned goal. Based on this consideration, Eudragit® Retard RS100 and RL100 resins were selected as positively charged copolymers to prepare polymeric NPs with potential mucoadhesive properties suitable for intranasal application. NPs were produced by the Quasi-emulsion Solvent Evaporation (QESD) method and loaded with diclofenac acid (DIC) or its epolamine salt (DIEP). Preliminary investigations were performed to obtain the optimized blank formulation and drugs loaded NPs evaluating different parameters that can affect particles size and polydispersity. The optimized formulations unloaded and loaded with DIC and DIEP were further evaluated for their thermotropic behavior by differential scanning calorimetry. Mucoadhesive evaluation was assessed by measuring variation in zeta potential and by turbidimetric assay after incubation of particles with mucin in simulated nasal fluid (SNF) at 37 °C at different time points (0, 1 and 24 h) compared to the pure suspensions. Stability of DIC and DIEP loaded NPs was also evaluated in SNF to predict potential aggregation phenomena after nasal administration. Finally, in vivo experiments showed absence of toxicity on the nasal mucosa of mice.

Polysorbate-Based Drug Formulations for Brain-Targeted Drug Delivery and Anticancer Therapy

Polysorbates (PSs) are synthetic nonionic surfactants consisting of polyethoxy sorbitan fatty acid esters. PSs have been widely employed as emulsifiers and stabilizers in various drug formulations and food additives. Recently, various PS-based formulations have been developed for safe and efficient drug delivery. This review introduces the general features of PSs and PS-based drug carriers, summarizes recent progress in the development of PS-based drug formulations, and discusses the physicochemical properties, biological safety, P-glycoprotein inhibitory properties, and therapeutic applications of PS-based drug formulations. Additionally, recent advances in brain-targeted drug delivery using PS-based drug formulations have been highlighted. This review will help researchers understand the potential of PSs as effective drug formulation agents.

Colloidal nanosystems with mucoadhesive properties designed for ocular topical delivery

Over the last years, the scientific interest about topical ocular delivery targeting the posterior segment of the eye has been increasing. This is probably due to the fact that this is a non-invasive administration route, well tolerated by patients and with fewer local and systemic side effects. However, it is a challenging task due to the external ocular barriers, tear film clearance, blood flow in the conjunctiva and choriocapillaris and due to the blood-retinal barriers, amongst other features. An enhanced intraocular bioavailability of drugs can be achieved by either improving corneal permeability or by improving precorneal retention time. Regarding this last option, increasing residence time in the precorneal area can be achieved using mucoadhesive polymers such as xyloglucan, poly(acrylate), hyaluronic acid, chitosan, and carbomers. On the other hand, colloidal particles can interact with the ocular mucosa and enhance corneal and conjunctival permeability. These nanosystems are able to deliver a wide range of drugs, including macromolecules, providing stability and improving ocular bioavailability. New pharmaceutical approaches based on nanotechnology associated to bioadhesive compounds have emerged as strategies for a more efficient treatment of ocular diseases. Bearing this in mind, this review provides an overview of the current mucoadhesive colloidal nanosystems developed for ocular topical administration, focusing on their advantages and limitations.

Advanced nanodelivery platforms for topical ophthalmic drug delivery

Conventional eye drops have several limitations, including the need for multiple applications per dose, hourly based dosage regiments, and suboptimal ocular bioavailability (<5%). The efficacy of topical ophthalmic medications can be significantly improved by controlling their contact time with the adherent mucin layer and by inducing sustained release properties, thus allowing for a prolonged contact time of the drug with the ocular tissues, which eventually will lead to improved drug bioavailability and a significant decrease in the frequency of eyedrop instillation. In this review, we critically highlight recent and innovative nanodrug delivery platforms, with a primary focus on the integration of nanotechnology, biomaterials, and polymer chemistry to facilitate precise spatial and temporal control over sustained drug release to the cornea.

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.

Expedition of Eudragit® Polymers in the Development of Novel Drug Delivery Systems

Eudragit® polymer has been widely used in film-coating for enhancing the quality of products over other materials (e.g., shellac or sugar). Eudragit® polymers are obtained synthetically from the esters of acrylic and methacrylic acid. For the last few years, they have shown immense potential in the formulations of conventional, pH-triggered, and novel drug delivery systems for incorporating a vast range of therapeutics including proteins, vitamins, hormones, vaccines, and genes. Different grades of Eudragit® have been used for designing and delivery of therapeutics at a specific site via the oral route, for instance, in stomach-specific delivery, intestinal delivery, colon-specific delivery, mucosal delivery. Further, these polymers have also shown their great aptitude in topical and ophthalmic delivery. Moreover, available literature evidences the promises of distinct Eudragit® polymers for efficient targeting of incorporated drugs to the site of interest. This review summarizes some potential researches that are being conducted by eminent scientists utilizing the distinct grades of Eudragit® polymers for efficient delivery of therapeutics at various sites of interest.

Dexibuprofen Biodegradable Nanoparticles: One Step Closer towards a Better Ocular Interaction Study

Ocular inflammation is one of the most prevalent diseases in ophthalmology, which can affect various parts of the eye or the surrounding tissues. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, are commonly used to treat ocular inflammation in the form of eye-drops. However, their bioavailability in ocular tissues is very low (less than 5%). Therefore, drug delivery systems such as biodegradable polymeric PLGA nanoparticles constitute a suitable alternative to topical eye administration, as they can improve ocular bioavailability and simultaneously reduce drug induced side effects. Moreover, their prolonged drug release can enhance patient treatment adherence as they require fewer administrations. Therefore, several formulations of PLGA based nanoparticles encapsulating dexibuprofen (active enantiomer of Ibuprofen) were prepared using the solvent displacement method employing different surfactants. The formulations have been characterized and their interactions with a customized lipid corneal membrane model were studied. Ex vivo permeation through ocular tissues and in vivo anti-inflammatory efficacy have also been studied.

Emerging role of nanosuspensions in drug delivery systems

Rapid advancement in drug discovery process is leading to a number of potential new drug candidates having excellent drug efficacy but limited aqueous solubility. By virtue of the submicron particle size and distinct physicochemical properties, nanosuspension has the potential ability to tackle many formulation and drug delivery issues typically associated with poorly water and lipid soluble drugs. Conventional size reduction equipment such as media mill and high-pressure homogenizers and formulation approaches such as precipitation, emulsion-solvent evaporation, solvent diffusion and microemulsion techniques can be successfully implemented to prepare and scale-up nanosuspensions. Maintaining the stability in solution as well as in solid state, resuspendability without aggregation are the key factors to be considered for the successful production and scale-up of nanosuspensions. Due to the considerable enhancement of bioavailability, adaptability for surface modification and mucoadhesion for drug targeting have significantly expanded the scope of this novel formulation strategy. The application of nanosuspensions in different drug delivery systems such as oral, ocular, brain, topical, buccal, nasal and transdermal routes are currently undergoing extensive research. Oral drug delivery of nanosuspension with receptor mediated endocytosis has the promising ability to resolve most permeability limited absorption and hepatic first-pass metabolism related issues adversely affecting bioavailability. Advancement of enabling technologies such as nanosuspension can solve many formulation challenges currently faced among protein and peptide-based pharmaceuticals.

Preparation and Evaluation of Eudragit® L100 Nanoparticles Loaded Impregnated with KT Tromethamine Loaded PVA -HEC Insertions for Ophthalmic Drug Delivery

Purpose: The purpose of the present study was to improve the ocular delivery for ketorolac tromethamine (KT) used to treat inflammation of the eye.

Methods: Eudragit nanoparticles loaded with KT were prepared and incorporated in polyvinyl alcohol (PVA) and hydroxyethyl cellulose (HEC) films. Nanoparticles were characterized by Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM). Physicochemical properties and encapsulation effciency were investigated for nanoparticles. Also, the inserts were evaluated for their physiochemical parameters like percentage moisture absorption, percentage moisture loss, thickness and folding endurance.

Results: Mean particle size and zeta potential were in range of 153.8-217 nm and (-10.8) - (-40.7) mV, respectively. The results show that the use of a surfactant has not led to any major change on drug loading. The loading increases with the amount of polymer. The insert had a thickness varying from 0.072 ± 0.0098 to 0.0865 ± 0.0035 mm. The thicknesses of the inserts and the folding endurance increased with the total polymer concentration. The physicochemical properties showed that the Eudragit® L-100 nanoparticles loaded PVA-HEC films could be an effective carrier for KT.

Conclusion: For the first time, inserts of Eudragit nanoparticles were successfully prepared for ophthalmic drug delivery system to prevent frequent drug administration and enhance patient compliance.

Optimization of the Interaction between Diclofenac and Ibuprofen with Benzalkonium Chloride to Prepare Ocular Nanosuspension

BACKGROUND

Non-steroidal anti-inflammatory drugs are most commonly used in the management of ocular inflammations. These drugs have poorly aqueous solubility and weakly acidic nature. They interact with cationic quaternary ammonium compound benzalkonium chloride, used as a preservative in ophthalmic formulations, to form insoluble complexes. To overcome this incompatibility solubilizers like polysorbate 80, lysine salts, tocopheryl polyethylene glycol succinate etc. are used which are quite irritating and affect the corneal integrity.

OBJECTIVE

The objective of the present study is to formulate nonirritating, compatible, microbiologically stable ophthalmic formulation with good corneal permeation characteristics. The interaction between diclofenac sodium or ibuprofen with benzalkonium chloride was optimized using a central composite experimental design to prepare nanosuspensions by nanoprecipitation.

METHODS

The optimized batches of nanosuspensions were evaluated for ex vivo corneal permeation study, preservative challenge test and physical stability. The optimal concentrations of benzalkonium chloride for diclofenac sodium (0.1%, w/v) and ibuprofen (0.1% w/v) nanosuspensions were determined to be 0.002%(w/v), which had a respective average particle size of 440 nm and 331 nm, respectively. The nanosuspensions of diclofenac sodium and ibuprofen provided 1.6 and 2.1- fold higher ex vivo corneal permeation than their respective conventional aqueous solution dosage forms. Further, the concentration of benzalkonium chloride used in the formulations showed adequate preservative efficacy.

RESULTS

The optimized nanosuspension formulations of diclofenac and ibuprofen were found to be physically stable and microbiologically safe with greater corneal penetration than the conventional solution dosage forms.

Novel ultra-small micelles based on ginsenoside Rb1: a potential nanoplatform for ocular drug delivery

OBJECTIVES

Ginsenosides Rb1 (Rb1) could form micelles in aqueous solutions. Self-assembled Rb1 micelles could potentially be utilized as ocular drug delivery system, and it was postulated that the encapsulation of a medicine within Rb1 micelles might strengthen the drug's therapeutic action and reduce side effects.

METHODS

Diclofenac-loaded Rb1 micelles (Rb1-Dic micelles) were formulated, optimized, and then further evaluated for in vitro cytotoxicity/in vivo ocular irritation, in vivo corneal permeation, and in vivo anti-inflammatory efficacy.

RESULTS

Rb1 self-assembled into micelles with ultra-small particle size (<8 nm) in a homogeneous distribution state (polydispersity index [PDI] < 0.3). Diclofenac was highly encapsulated into the micelles according to the weight ratios of Rb1 to diclofenac. The ophthalmic solution of Rb1-Dic micelle was simple to prepare. Rb1 had good cellular tolerance, and it also improved the cellular tolerance of the encapsulated diclofenac. Rb1-Dic micelles also showed non-irritants to the rabbit eyes. The use of Rb1 micelles significantly improved the in vivo corneal permeation as well as the anti-inflammatory efficacy of diclofenac when compared to commercial diclofenac eye drops.

CONCLUSION

Rb1 micelle formulations have great potential as a novel ocular drug delivery system to improve the bioavailability of drugs such as diclofenac.

Design, development and characterization of ketorolac tromethamine polymeric nanosuspension

Aim: At present, various ophthalmic formulations show low bioavailability. The rationale of present work was to design and develop stable ketorolac tromethamine nanosuspension with sustained effect and greater permeability for ocular drug delivery and increased ocular residence. Materials & methods: Formulations were designed by using central composite design, developed by combined nanoprecipitation and probe sonication method. Results & discussion: Nanosuspensions depicted the size range of the particles in between 199 and 441 nm with slight reduction in crystallinity of drug. In vitro drug release revealed that higher % entrapment efficiency of drug in nanosuspension delays the drug release. Conclusion: Eudragit RL-100-based nanosuspension increases viscosity and avoids problems like drug loss from precorneal surface and rapid drainage through nasolacrimal areas.

Ultra-small micelles based on polyoxyl 15 hydroxystearate for ocular delivery of myricetin: optimization, in vitro, and in vivo evaluation

The aim was to develop a nanocarrier based on polyoxyl 15 hydroxystearate (Kolliphor® HS15, HS15) micelles for the solubility, stability, and ocular delivery of myricetin (Myr). An optimized ratio of HS15 and Myr was prepared to fabricate HS15-Myr micelle ophthalmic solution. Myr-encapsulating HS15 micelles (HS15-Myr micelles) were subjected to physicochemical characterizations. The chemical stability of Myr in HS15 micelles and storage stability of HS15-Myr micelle ophthalmic solutions were evaluated. In vitro parallel artificial membrane permeability assay and antioxidant activity of Myr in HS15 micelles were also measured. In vivo ocular tolerance, corneal permeation, and anti-inflammatory efficacy studies were conducted following ocular topical administration. HS15-Myr micelles were successfully prepared and presented transparent appearance with high encapsulation (96.12 ± 0.31%), ultra-small micelle size (a mean diameter of 12.17 ± 0.73 nm), uniform size distribution (polydispersity index [PDI] = 0.137 ± 0.013), and negative surface charge (- [4.28 ± 0.42] mV). Myr in HS15 micelle solution demonstrated higher aqueous stability than the free Myr solution among the accepted pH range for eyedrops. HS15-Myr micelle ophthalmic solution demonstrated high storage stability at 4 °C and 25 °C. HS15 micelles could significantly improve in vitro antioxidant activity and faster membrane permeation of Myr. No irritations or corneal damage were revealed in rabbit eyes after ocular administration of HS15-Myr micelle solution. In vivo corneal permeation study demonstrated that HS15-Myr micelles could penetrate the cornea efficiently in mouse eyes. Further, HS15-Myr micelles also demonstrated significant in vivo anti-inflammatory activity. It can be concluded that HS15 micelles are a potential ophthalmic delivery nanocarrier for poorly soluble drugs such as Myr.

Parenteral nanosuspensions: a brief review from solubility enhancement to more novel and specific applications

Advancements in in silico techniques of lead molecule selection have resulted in the failure of around 70% of new chemical entities (NCEs). Some of these molecules are getting rejected at final developmental stage resulting in wastage of money and resources. Unfavourable physicochemical properties affect ADME profile of any efficacious and potent molecule, which may ultimately lead to killing of NCE at final stage. Numerous techniques are being explored including nanocrystals for solubility enhancement purposes. Nanocrystals are the most successful and the ones which had a shorter gap between invention and subsequent commercialization of the first marketed product. Several nanocrystal-based products are commercially available and there is a paradigm shift in using approach from simply being solubility enhancement technique to more novel and specific applications. Some other aspects in relation to parenteral nanosuspensions are concentrations of surfactant to be used, scalability and in vivo fate. At present, there exists a wide gap due to poor understanding of these critical factors, which we have tried to address in this review. This review will focus on parenteral nanosuspensions, covering varied aspects especially stabilizers used, GRAS (Generally Recognized as Safe) status of stabilizers, scalability challenges, issues of physical and chemical stability, solidification techniques to combat stability problems and in vivo fate.

Tolnaftate–graphene composite-loaded nanoengineered electrospun scaffolds as efficient therapeutic dressing material for regimen of dermatomycosis

Graphene “The novel carbon nano-trope” tailors auspicious platform for designing antimicrobial regimen by virtue of its conspicuous molecular interaction with the microorganism. In this work, Tolnaftate (Tf), an antifungal drug, was mingled with Graphene nanoplatelets (Gn) to develop composite (Tf–Gn) via the wet chemical route, embedded in a biocompatible polymeric blend of Eudragit RL100/Eudragit RS100 (EuRL100/EuRS100) and subjected to electrospinning to obtain nonwoven nanoengineered scaffolds (nanofibers) for enhanced anti-dermatophytic virtue. Pursuing cluster of optimization experiments, 20% w/v EuRL100/EuRS 100 was found to be adequate for formation of smooth, defect-free, and regular fibers. Field emission electron microscopy (FESEM) acknowledged zestfully fabrication of smooth, shiny, nano-range, and mesh-like architecture, comprising distinct pockets within their structure. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC) conceded formation of the composite Tf–Gn, its physical compatibility with polymers, and improved thermal behavior. Exceptional swelling capacity, significant hydrophilicity, and immense drug entrapment efficiency were obtained of nanofibers fabricated from 3:1 ratio of EuRL100/EuRS100 polymers blend owing to relatively higher permeability which gratified essential benchmark for fabrication of nanofibrous scaffold to alleviate fungal infections caused by dermatophytes. In vitro drug release interpreted controlled liberation of Tf in dissolution media, following Korsmeyer–Peppas model kinetics, and suggested a diffusion-based mechanism. Microdilution broth method was performed for in vitro antifungal efficacy against extremely devastating dermatophytes, i.e., anthropophilic Trichophyton rubrum and zoophilic Microsporum canis, exhibited preeminent growth inhibition against T.rubrum and scanty for M.canis. Findings revealed the superior antifungal activity of Tf–Gn-loaded nanofibers as compared to Tf-loaded nanofibers and recommended potential dressing materials for an effective regimen of dermatomycosis.

Nanoparticles for drug delivery to the anterior segment of the eye

Commercially available ocular drug delivery systems are effective but less efficacious to manage diseases/disorders of the anterior segment of the eye. Recent advances in nanotechnology and molecular biology offer a great opportunity for efficacious ocular drug delivery for the treatments of anterior segment diseases/disorders. Nanoparticles have been designed for preparing eye drops or injectable solutions to surmount ocular obstacles faced after administration. Better drug pharmacokinetics, pharmacodynamics, non-specific toxicity, immunogenicity, and biorecognition can be achieved to improve drug efficacy when drugs are loaded in the nanoparticles. Despite the fact that a number of review articles have been published at various points in the past regarding nanoparticles for drug delivery, there is not a review yet focusing on the development of nanoparticles for ocular drug delivery to the anterior segment of the eye. This review fills in the gap and summarizes the development of nanoparticles as drug carriers for improving the penetration and bioavailability of drugs to the anterior segment of the eye.

Non-invasive strategies for targeting the posterior segment of eye

The safe and effective treatment of eye diseases has been remained a global myth. Several advancements have been done and various drug delivery and treatment techniques have been suggested. The Posterior segment disorders are the leading cause of visual impairments and blindness. Targeting the therapeutic agents to the anterior and posterior segments of the eye has attracted extensive attention from the scientific community. Significant key factors in the success of ocular therapy are the development of safe, effective, economic and non-invasive novel drug delivery systems. These specialized non-invasive ocular drug delivery systems revolutionized the drug delivery strategies by overcoming the limitations, provided targeted delivery to the ocular tissues by avoiding larger doses, and reducing the toxicity encountered by the conventional approaches. These non-invasive systems are fabricated by ingredients encompassing biodegradability, biocompatibility, mucoadhesion, solubility and permeability enhancement and stimuli responsiveness. The variety of routes are utilized to provide minimally invasive drug delivery to the patients without any discomfort and pain. This review is focused on the brief introduction, types, significance, preparation techniques, components and mechanism of drug release of non-invasive systems, including in situ gelling systems, microspheres, iontophoresis, nanoparticles, nanosuspensions and specialized novel emulsions.

New nanomicelle curcumin formulation for ocular delivery: improved stability, solubility, and ocular anti-inflammatory treatment

CONTEXT

A stable topical ophthalmic curcumin formulation with high solubility, stability, and efficacy is needed for pharmaceutical use in clinics.

OBJECTIVES

The objective of this article was to describe a novel curcumin containing a nanomicelle formulation using a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (PVCL-PVA-PEG) graft copolymer.

METHODS

Nanomicelle curcumin was formulated and optimized and then further evaluated for in vitro cytotoxicity/in vivo ocular irritation, in vitro cellular uptake/in vivo corneal permeation, and in vitro antioxidant activity/in vivo anti-inflammatory efficacy.

RESULTS

The solubility, chemical stability, and antioxidant activity were greatly improved after the encapsulation of the PVCL-PVA-PEG nanomicelles. The nanomicelle curcumin ophthalmic solution was simple to prepare and the nanomicelles are stable to the storage conditions, and it had good cellular tolerance. Nanomicelle curcumin also had excellent ocular tolerance in rabbits. The use of nanomicelles significantly improved in vitro cellular uptake and in vivo corneal permeation as well as improved anti-inflammatory efficacy when compared with a free curcumin solution.

CONCLUSIONS

These findings indicate that nanomicelles could be promising topical delivery systems for the ocular administration of curcumin.

Nanosuspensions in Nanobiomedicine

The tremendous success in developing new nanomaterials and fostering technological innovation arises from the focus on interdisciplinary research and collaboration between physical and medical scientists. The concept of nano-medicine is one of the most important and exciting ideas ever generated by the applications of nanoscience. One of the most challenging tasks in the pharmaceutical industry is the formulation of poorly soluble drugs. The implication of conventional techniques for improving the solubility has gained limited success. Nanoparticles facilitate formulation with improved solubility and efficacy mainly through nanosuspension approach. Techniques such as media milling, high-pressure homogenization, and use of microemulsion have been used for production of nanosuspensions for a novel delivery system. Moreover, they are manoeuvred to patient-acceptable dosage forms like tablets, capsules, and lyophilized powder products. Nanosuspension technology has also been studied for active and passive targeted drug delivery systems, which the chapter highlights on various formulational perspectives and applications as a biomedicine delivery system.

A novel nanoparticles impregnated ocular insert for enhanced bioavailability to posterior segment of eye: In vitro, in vivo and stability studies

The present investigation was carried out to demonstrate with the help of in vitro and in vivo studies that nanoparticles impregnated ocular inserts effectively delivers significant concentration of drug to the posterior segment of eye after topical administration for treatment of glaucoma. Drug loaded Nanoparticles and their ocular insert have been reported to reduce side effects of orally administered Acetazolamide. Eudragit NPs were prepared by the solvent diffusion nanoprecipitation technique. The prepared NPs were evaluated for various parameters such as particle size, zeta potential, % entrapment efficiency, % drug loading, DSC, FTIR, TEM and stability studies. Ocular inserts of NPs were prepared by solvent casting method. The prepared ocular inserts were evaluated for thickness, content uniformity, folding endurance, disintegration time, morphology and stability study. The NPs and ocular inserts were evaluated for in-vitro drug diffusion study, ex-vivo trans-corneal permeability study, in-vivo ocular tolerability and intra ocular pressure (IOP) reduction study. The optimized batch was stable for a period of 3months in lyophilized form. The optimized formulations had size range of 367nm±8nm, zeta potential around +7mV±1.3mV and 51.61%±3.84% entrapment efficiency with 19%±1.40% drug loading. The ex-vivo trans-corneal study showed higher cumulative corneal permeation, flux across corneal tissue (2.460±0.028μg/ml) and apparent corneal permeability (3.926×10^-6cm²/s & 3.863×10^-6cm²/s) from drug loaded Eudragit NPs and Ocular inserts as compared to drug solution (0.671±0.020μg/ml & 3.166×10^-6cm²/s). In-vivo study showed the Eudragit NPs and ocular insert produced significant (P<0.001) lowering in intra ocular pressure compared with the solution of free drug after 3h of topical ocular administration. Plain Eudragit NPs caused no inflammation and/or discomfort in rabbit eyes and neither affected the intra ocular pressure establishing their safety and non irritancy.

Ophthalmic applications of lipid-based drug nanocarriers: an update of research and patenting activity

Ophthalmic diseases collect great attention by researchers and pharmaceutical technologists, since they can dramatically worsen the quality of life. Because of the limited duration of action on the eye surface, and anatomical/physiological barriers to drug penetration from it into the inner eye structures, conventional ocular formulations are generally unable to perform at their best. Nanotechnology approaches can represent a solution to improve the therapeutic efficiency, compliance and safety of ocular drugs. In this respect, lipid-based nanocarriers are among the most interesting systems. Their composition and production methods make them highly biocompatible and safe formulations. This review illustrates the developments achieved in ocular drug delivery using lipid-based nanocarriers, with a critical revision of recent scientific articles and filed patents.

Conjugation of cell-penetrating peptides with poly(lactic-co-glycolic acid)-polyethylene glycol nanoparticles improves ocular drug delivery

In this work, a peptide for ocular delivery (POD) and human immunodeficiency virus transactivator were conjugated with biodegradable poly(lactic-co-glycolic acid) (PGLA)-polyethylene glycol (PEG)-nanoparticles (NPs) in an attempt to improve ocular drug bioavailability. The NPs were prepared by the solvent displacement method following two different pathways. One involved preparation of PLGA NPs followed by PEG and peptide conjugation (PLGA-NPs-PEG-peptide); the other involved self-assembly of PLGA-PEG and the PLGA-PEG-peptide copolymer followed by NP formulation. The conjugation of the PEG and the peptide was confirmed by a colorimetric test and proton nuclear magnetic resonance spectroscopy. Flurbiprofen was used as an example of an anti-inflammatory drug. The physicochemical properties of the resulting NPs (morphology, in vitro release, cell viability, and ocular tolerance) were studied. In vivo anti-inflammatory efficacy was assessed in rabbit eyes after topical instillation of sodium arachidonate. Of the formulations developed, the PLGA-PEG-POD NPs were the smaller particles and exhibited greater entrapment efficiency and more sustained release. The positive charge on the surface of these NPs, due to the conjugation with the positively charged peptide, facilitated penetration into the corneal epithelium, resulting in more effective prevention of ocular inflammation. The in vitro toxicity of the NPs developed was very low; no ocular irritation in vitro (hen's egg test-chorioallantoic membrane assay) or in vivo (Draize test) was detected. Taken together, these data demonstrate that PLGA-PEG-POD NPs are promising vehicles for ocular drug delivery.

Enhanced corneal permeation of coumarin-6 using nanoliposomes containing dipotassium glycyrrhizinate: in vitro mechanism and in vivo permeation evaluation

The fluidity of the liposomal membrane differently affected cellular uptake/internalization and in vivo corneal penetration of the nanoliposomes.

Clavanin bacterial sepsis control using a novel methacrylate nanocarrier

Controlling human pathogenic bacteria is a worldwide problem due to increasing bacterial resistance. This has prompted a number of studies investigating peptides isolated from marine animals as a possible alternative for control of human pathogen infections. Clavanins are antimicrobial peptides isolated from the marine tunicate Styela clava, showing 23 amino acid residues in length, cationic properties, and also high bactericidal activity. In spite of clear benefits from the use of peptides, currently 95% of peptide properties have limited pharmaceutical applicability, such as low solubility and short half-life in the circulatory system. Here, nanobiotechnology was used to encapsulate clavanin A in order to develop nanoantibiotics against bacterial sepsis. Clavanin was nanostructured using EUDRAGIT^® L 100-55 and RS 30 D solution (3:1 w:w). Atomic force, scanning electron microscopy and dynamic light scattering showed nanoparticles ranging from 120 to 372 nm in diameter, with a zeta potential of -7.16 mV and a polydispersity index of 0.123. Encapsulation rate of 98% was assessed by reversed-phase chromatography. In vitro bioassays showed that the nanostructured clavanin was partially able to control development of Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Furthermore, nanostructures did not show hemolytic activity. In vivo sepsis bioassays were performed using C57BL6 mice strain inoculated with a polymicrobial suspension. Assays led to 100% survival rate under sub-lethal sepsis assays and 40% under lethal sepsis assays in the presence of nanoformulated clavanin A until the seventh day of the experiment. Data here reported indicated that nanostructured clavanin A form shows improved antimicrobial activity and has the potential to be used to treat polymicrobial infections.

Nanocrystals: industrially feasible multifunctional formulation technology for poorly soluble actives

Poor solubility of new drugs and their related low oral bioavailability and general delivery problems are becoming a major challenge. Nanocrystals being a kind of "universal" formulation approach for these molecules are reviewed in this paper regarding the industrial feasibility, i.e. industrially available production processes (bottom-up and top-down technologies), regulatory aspects and nanotoxicology. This article also includes second generation nanocrystals (<<100 nm) as smartCrystals. The status of products on the market and in clinical phases is presented. The different special features of nanocrystals, which are exploited in different products, are described (tablets, capsule, aqueous nanosuspension). The main focus is given for oral and intravenous products. However, the potential and delivery strategies for other administration routes are discussed, i.e. dermal and mucosal, ocular, pulmonary and targeted delivery (e.g. via differential protein adsorption to the brain). In addition, the potential of the nanocrystal technology for delivery of poorly soluble, non-pharmaceutical actives is highlighted, i.e. in cosmetics or nutraceuticals.

Eudragit RL100 nanoparticle system for the ophthalmic delivery of cloricromene

A Eudragit RL100 polymer nanoparticle system loaded with cloricromene was prepared and characterized on the basis of physicochemical properties, stability and drug release features. To investigate the ocular bioavailability of cloricromene after inclusion in the polymer matrix, the new nanoparticle system was topically administered in the rabbit eye and compared with an aqueous solution of the same drug. The nanoparticle system showed interesting size distribution and surface charge values, suitable for ophthalmic application. The results indicated that the dispersion of cloricromene within Eudragit RL100 polymer nanoparticles increased its ocular bioavailability and enhanced the biopharmaceutical profile. The new cloricromene-loaded nanoparticle system described here may be useful in clinical practice.

Targeted drug-delivery approaches by nanoparticulate carriers in the therapy of inflammatory diseases

Limitations in therapy induced by adverse effects due to unselective drug availability and therefore the use of potentially too high doses are a common problem. One prominent example for this dilemma are inflammatory diseases. Colloidal carriers allow one to improve delivery of drugs to the site of action and appear promising to overcome this general therapeutic drawback. Specific uptake of nanoparticles by immune-related cells in inflamed barriers offers selective drug targeting to the inflamed tissue. Here we focus on nanocarrier-based drug delivery strategies for the treatment of common inflammatory disorders like rheumatoid arthritis, multiple sclerosis, uveitis or inflammatory bowel disease.

Eudragit® microparticles as a possible tool for ophthalmic administration of acyclovir

This paper describes the production and characterization of polyacrylic polymer (Eudragit RL, RS and NE) microparticles by spray drying method. Microparticles were designed for ophthalmic administration of acyclovir. Microparticle morphology was characterized by optical and electron microscopy. The release kinetics of the drug from microspheres were determined by a dialysis method. The spray drying method described allows the production of microparticles with acceptable encapsulation efficiency and appropriate dimensional characteristics for ophthalmic administration. Release profile data indicate that acyclovir is released from microparticles in a controlled manner. In addition the release pattern of the drug is influenced by the type of Eudragit used for microparticle production. Moreover the plaque reduction efficiency of acyclovir containing microparticles (except for RS/NE microspheres) is comparable to that displayed by the free drug. Finally our results suggest that acyclovir containing microparticles could represent an interesting system for the release of this antiviral drug at the eye site.

Flurbiprofen loaded biodegradable nanoparticles for ophtalmic administration

Poly(lactic/glycolic) acid nanoparticles incorporating flurbiprofen (FB) were prepared by the solvent displacement technique using poloxamer 188 as a stabilizer to improve the availability of the drug for the prevention of the inflammation caused by ocular surgery. A 2(3) + star design was applied to investigate the influence of several factors such as the pH of the aqueous phase, the initial concentration of the stabilizer, and the drug used to prepare the nanoparticles (NPs) on the physicochemical properties (particle size analysis, zeta potential, and drug loading efficiency) of the colloidal system. The best formulations were those prepared at pH 3.5 with a concentration of 1.5 mg/mL of FB and 10 or 20 mg/mL of poloxamer 188. These formulations showed an appropriate average size for ophthalmic administration (232.8 and 277.6 nm, respectively) and a good yield of entrapment efficiency (94.60% and 93.55%, respectively). The release behavior of FB from the developed NPs was complete and exhibited a biphasic pattern. Formulations did not show toxicity on ocular tissues. In vivo anti-inflammatory efficacy was assessed in the rabbit eye after topical instillation of sodium arachidonate (SA). A higher decrease of the SA-induced inflammation was obtained for the NP formulations.

Nanomedicine: An unresolved regulatory issue

Nanomedicine is a science that uses nanotechnology to maintain and improve human health at the molecular scale. Current and potential applications of nanotechnology in medicine range from research involving diagnostic devices, drug delivery vehicles to enhanced gene therapy and tissue engineering procedures. Its advantage over conventional medicine lies on its size. Particle size has effect on serum lifetime and pattern of deposition. This allows drugs of nanosize be used in lower concentration and has an earlier onset of therapeutic action. It also provides materials for controlled drug delivery by directing carriers to a specific location. Major efforts are underway, however, very little attention is devoted to assessment of health risks to human or to the ecosystem. Inhaled nanoparticles have already been related to lung injury. It is recognized that physico-chemical properties in conjunction with environmental factors and stability of the nanomaterial all contribute to the overall toxicological responses. Nanotoxicological information, currently insufficient, will be vital in aiding academia, industry and regulatory bodies in elucidating the mechanisms of action, balancing its risk and benefit, thus maximizing the utility of these materials in medicine without compromising public health and environmental integrity.

Nanotechnology: intelligent design to treat complex disease

The purpose of this expert review is to discuss the impact of nanotechnology in the treatment of the major health threats including cancer, infections, metabolic diseases, autoimmune diseases, and inflammations. Indeed, during the past 30 years, the explosive growth of nanotechnology has burst into challenging innovations in pharmacology, the main input being the ability to perform temporal and spatial site-specific delivery. This has led to some marketed compounds through the last decade. Although the introduction of nanotechnology obviously permitted to step over numerous milestones toward the development of the "magic bullet" proposed a century ago by the immunologist Paul Ehrlich, there are, however, unresolved delivery problems to be still addressed. These scientific and technological locks are discussed along this review together with an analysis of the current situation concerning the industrial development.