Development and Evaluation of Diclofenac Sodium Loaded-N-Trimethyl Chitosan Nanoparticles for Ophthalmic Use

Absorption enhancement strategies in chitosan-based nanosystems and hydrogels intended for ocular delivery: Latest advances for optimization of drug permeation

Ophthalmic diseases can be presented as acute diseases like allergies, ocular infections, etc., or chronic ones that can be manifested as a result of systemic disorders, like diabetes mellitus, thyroid, rheumatic disorders, and others. Chitosan (CS) and its derivatives have been widely investigated as nanocarriers in the delivery of drugs, genes, and many biological products. The biocompatibility and biodegradability of CS made it a good candidate for ocular delivery of many ingredients, including immunomodulating agents, antibiotics, ocular hypertension medications, etc. CS-based nanosystems have been successfully reported to modulate ocular diseases by penetrating biological ocular barriers and targeting and controlling drug release. This review provides guidance to drug delivery formulators on the most recently published strategies that can enhance drug permeation to the ocular tissues in CS-based nanosystems, thus improving therapeutic effects through enhancing drug bioavailability. This review will highlight the main ocular barriers to drug delivery observed in the nano-delivery system. In addition, the CS physicochemical properties that contribute to formulation aspects are discussed. It also categorized the permeation enhancement strategies that can be optimized in CS-based nanosystems into four aspects: CS-related physicochemical properties, formulation components, fabrication conditions, and adopting a novel delivery system like implants, inserts, etc. as described in the published literature within the last ten years. Finally, challenges encountered in CS-based nanosystems and future perspectives are mentioned.

Exploring the Ocular Absorption Pathway of Fasudil Hydrochloride towards Developing a Nanoparticulate Formulation with Improved Performance

Rho-kinase (ROCK) inhibitors represent a new category of anti-glaucoma medications. Among them, Fasudil hydrochloride, a selective ROCK inhibitor, has demonstrated promising outcomes in glaucoma treatment. It works by inhibiting the ROCK pathway, which plays a crucial role in regulating the trabecular meshwork and canal of Schlemm's aqueous humor outflow. This study aims to investigate the ocular absorption pathway of Fasudil hydrochloride and, subsequently, develop a nanoparticle-based delivery system for enhanced corneal absorption. Employing the ionic gelation method and statistical experimental design, the factors influencing chitosan nanoparticle (Cs NP) characteristics and performance were explored. Fasudil in vitro release and ex vivo permeation studies were performed, and Cs NP ocular tolerability and cytotoxicity on human lens epithelial cells were evaluated. Permeation studies on excised bovine eyes revealed significantly higher Fasudil permeation through the sclera compared to the cornea (370.0 μg/cm2 vs. 96.8 μg/cm2, respectively). The nanoparticle size (144.0 ± 15.6 nm to 835.9 ± 23.4 nm) and entrapment efficiency range achieved (17.2% to 41.4%) were predominantly influenced by chitosan quantity. Cs NPs showed a substantial improvement in the permeation of Fasudil via the cornea, along with slower release compared to the Fasudil aqueous solution. The results from the Hen's Egg Test Chorioallantoic Membrane (HET-CAM) and Bovine Corneal Opacity and Permeability (BCOP) tests indicated good conjunctival and corneal biocompatibility of the formulated chitosan nanoparticles, respectively. Lens epithelial cells displayed excellent tolerance to low concentrations of these nanoparticles (>94% cell viability). To the best of our knowledge, this is the first report on the ocular absorption pathway of topically applied Fasudil hydrochloride where the cornea has been identified as a potential barrier that could be overcome using Cs NPs.

Overview of Recent Advances in Nano-Based Ocular Drug Delivery

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

Development and Validation of Facile RP-HPLC Method for Simultaneous Determination of Timolol Maleate, Moxifloxacin Hydrochloride, Diclofenac Sodium and Dexamethasone in Plasma, Aqueous Humor and Pharmaceutical Products

The present study aimed to develop a validated RP-HPLC method for the simultaneous determination of timolol maleate (TM), moxifloxacin hydrochloride (MOXI), diclofenac sodium (DS) and dexamethasone (DEXA) in human plasma, bovine aqueous humor and pharmaceutical preparations. The chromatographic separation was studied using the C18 column. The chromatographic conditions, such as composition, pH, the flow rate of mobile phase, the temperature of column, wavelength of absorption and injection volume of the sample, were studied. The method was validated to confirm specificity, linearity and accuracy in accordance with an International Conference on Harmonization guidelines. The optimum conditions for separation included mobile phase 0.05 M monobasic phosphate buffer: acetonitrile (65:35 v/v), pH of buffer adjusted to 6.2 and the flow rate of 1 mL/minute. The optimum temperature of the column was found to be 35°C, absorption wavelength 265 nm and injection volume 50 μL. The baseline separation of all four drugs with good sensitivity, resolution, and a less than 15 min run time was achieved. The retention time of TM, MOXI, DS and DEXA were 4.3,5.7,9.9 and 13.5 minutes respectively. The limit of detection (LOD) values were 6.2, 4.8, 0.8 and 1.2 ng/mL for TM, MOXI, DS and DEXA, respectively, whereas their respective limit of quantification (LOQ) values was: were 42.6, 26.8, 5.6 and 6.2 ng/mL. The coefficient of variation for intra-day and inter-day were in the range of 0.32-1.57 and 1.29-3.07%, respectively. The method was found to be sensitive, precise and accurate in human plasma and bovine aqueous humor and can be applied for the quantification of these compounds in plasma, aqueous humor and pharmaceuticals.

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

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

Recent Advances in Chitosan-Based Applications-A Review

Chitosan derived from chitin gas gathered much interest as a biopolymer due to its known and possible broad applications. Chitin is a nitrogen-enriched polymer abundantly present in the exoskeletons of arthropods, cell walls of fungi, green algae, and microorganisms, radulae and beaks of molluscs and cephalopods, etc. Chitosan is a promising candidate for a wide variety of applications due to its macromolecular structure and its unique biological and physiological properties, including solubility, biocompatibility, biodegradability, and reactivity. Chitosan and its derivatives have been known to be applicable in medicine, pharmaceuticals, food, cosmetics, agriculture, the textile and paper industries, the energy industry, and industrial sustainability. More specifically, their use in drug delivery, dentistry, ophthalmology, wound dressing, cell encapsulation, bioimaging, tissue engineering, food packaging, gelling and coating, food additives and preservatives, active biopolymeric nanofilms, nutraceuticals, skin and hair care, preventing abiotic stress in flora, increasing water availability in plants, controlled release fertilizers, dye-sensitised solar cells, wastewater and sludge treatment, and metal extraction. The merits and demerits associated with the use of chitosan derivatives in the above applications are elucidated, and finally, the key challenges and future perspectives are discussed in detail.

Nanotechnology based drug delivery systems for the treatment of anterior segment eye diseases

Diseases affecting the anterior segment of the eye are the primary causes of vision impairment and blindness globally. Drug administration through the topical ocular route is widely accepted because of its user/patient friendliness - ease of administration and convenience. However, it remains a significant challenge to efficiently deliver drugs to the eye through this route because of various structural and physiological constraints that restrict the distribution of therapeutic molecules into the ocular tissues. The bioavailability of topically applied ocular medications such as eye drops is typically less than 5%. Developing novel delivery systems to increase the retention time on the ocular surfaces and permeation through the cornea is one of the approaches adopted to boost the bioavailability of topically administered medications. Drug delivery systems based on nanotechnology such as micelles, nanosuspensions, nanoparticles, nanoemulsions, liposomes, dendrimers, niosomes, cubosomes and nanowafers have been investigated as effective alternatives to conventional ocular delivery systems in treating diseases of the anterior segment of the eye. This review discussed different nanotechnology-based delivery systems that are currently investigated for treating and managing diseases affecting the anterior ocular tissues. We also looked at the challenges in translating these systems into clinical use and the prospects of nanocarriers as a vehicle for the delivery of phytoactive compounds to the anterior segment of the eye.

Preparation and Characterization of Chitosan/LDH Composite Membranes for Drug Delivery Application

In this study, composite membranes based on chitosan (CS), layered double hydroxide (LDH), and diclofenac were prepared via dispersing of LDH and diclofenac (DCF) in the chitosan matrix for gradual delivery of diclofenac sodium. The effect of using LDH in composites was compared to chitosan loaded with diclofenac membrane. LDH was added in order to develop a system with a long release of diclofenac sodium, which is used in inflammatory conditions as an anti-inflammatory drug. The prepared composite membranes were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope Analysis (SEM), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA) and UV-Vis Spectroscopy. The results of the FTIR and XPS analyses confirmed the obtaining of the composite membrane and the efficient incorporation of diclofenac. It was observed that the addition of LDH can increase the thermal stability of the composite membrane and favors the gradual release of diclofenac, highlighted by UV-Vis spectra that showed a gradual release in the first 48 h. In conclusion, the composite membrane based on CS-LDH can be used in potential drug delivery application.

A Novel Approach for the Availability and Ocular Delivery of Tenoxicam Potassium: Synthesis, Characterization, and In Vivo Application

Tenoxicam (TX) is a non-steroidal anti-inflammatory agent that can be used to control pain in various ophthalmic lesions like cataracts, refractive surgery, and corneal abrasion. TX has a very slightly aqueous solubility of 0.072 mg/mL resulting in difficulty to be formulated in ophthalmic solutions. This study aims to improve TX solubility by converting it into its potassium salt to achieve a target of 10 mg/mL (1%w/v) concentration of TX in the desired aqueous medium for the formulation of aqueous ophthalmic solutions. The synthesized TX salt was characterized by different evaluation parameters such as solubility studies, ¹H NMR, IR, and elemental analyses. Different TX potassium solutions were formulated at concentrations of 0.5% and 1% w/v using different viscosity-imparting agents. The prepared solutions were characterized for their physicochemical properties including visual inspection, pH, rheological, in vitro release, and kinetic behavior. Also, the formulations were biologically evaluated in vivo using male albino rabbits. The obtained results showed the successful synthesis of TX salt, as indicated by IR and NMR, and elemental analysis. The solubility study showed that the solubility of TX was improved hugely to 18 mg/mL (250-fold). In addition, the results showed that the prepared formulations showed acceptable physicochemical properties. The highest release rate was obtained with formula F1, which contains no viscosity-imparting agents. While as, the lowest release rate was obtained in the case of formula F9, composed of Pluronic F127 (12% w/v). The in vivo results showed that TX optimized ophthalmic solutions F8 and F9 inhibited the redness and edema in an extended or sustained manner.

Chitosan Encapsulated Meloxicam Nanoparticles for Sustained Drug Delivery Applications: Preparation, Characterization, and Pharmacokinetics in Wistar Rats

Meloxicam (MLX) is currently used in the therapeutic management of both acute and chronic inflammatory disorders such as pain, injuries, osteoarthritis, and rheumatoid arthritis in both humans and animals. Gastrointestinal toxicity and occasional renal toxicity were observed in patients taking it for a long-term period. Meloxicam's late attainment of peak plasma concentration results in a slow onset of action. The goal of the current study was to prepare and characterize chitosan encapsulated meloxicam nanoparticles (CEMNPs) with high bioavailability and less gastro intestinal toxicity in order to prevent such issues. The size of the prepared CEMNPs was approximately 110-220 nm with a zetapotential of +39.9 mV and polydispersity index of 0.268, suggesting that they were uniformly dispersed nanoparticles. The FTIR and UV-Vis spectroscopy have confirmed the presence of MLX in the prepared CEMNPs. The pharmacokinetics have been studied with three groups of male Wistar rats receiving either of the treatments, viz., 4 mg·kg-1 of MLX and 1 or 4 mg·kg-1 of CEMNPs. Plasma samples were collected until 48 h post administration, and concentrations of MLX were quantified by using reverse (C18) phase HPLC. Non-compartmental analysis was applied to determine pharmacokinetic variables. Upon oral administration, the maximum concentration (Cmax) was reached in 4 h for CEMNPs and 6 h for MLX. The mean area under the plasma MLX concentration-time curve from 'zero' to infinity (AUC0-∞), half-life (t1/2β), and mean resident time (MRT) of 1 mg·kg-1 of CEMNPs was 1.4-, 2-, and 1.8-fold greater than 4 mg·kg-1 of MLX. The prepared CEMNPs demonstrated quicker absorption and prolonged release along with a significant improvement in the bioavailability of MLX, paving a prospective path for the development of drugs with enhanced bioavailability with less side effects.

Chitosan Nanoparticles for Meloxicam Ocular Delivery: Development, In Vitro Characterization, and In Vivo Evaluation in a Rabbit Eye Model

Eye inflammation is considered one of the most common co-morbidities associated with ocular disorders and surgeries. Conventional management of this condition with non-steroidal anti-inflammatory drugs as eye drops is associated with low corneal bioavailability and ocular irritancy. In the current study, we first investigated the capacity of different solvent systems to enhance the solubility of Meloxicam (MLX). Then, we prepared chitosan nanoparticles loaded with meloxicam (MLX-CS-NPs) through electrostatic interaction between the cationic chitosan and the anionic MLX using either 100% v/v polyethylene glycol 400 or 0.25% w/v tripolyphosphate solution as solvents based on the MLX solubility data. In further studies, MLX-CS-NPs were characterized in vitro and assessed for their ex vivo corneal and scleral permeability. The morphology, average particle size (195–597 nm), zeta potential (25–54 mV), and percent entrapment efficiencies (70–96%) of the prepared MLX-CS-NPs were evaluated. The in vitro release study of MLX from the selected MLX-CS-NPs showed a sustained drug release for 72 h with accepted flux and permeation through the cornea and sclera of rabbits. In the in vivo studies, MLX-CS-NPs eye drop dispersion showed enhanced anti-inflammatory activity and no ocular irritancy compared to MLX-eye drop solution. Our findings suggest the potential for using chitosan nanotechnology for ocular delivery of MLX with high contact time and activity.

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.

Chitosan Nanoparticles at the Biological Interface: Implications for Drug Delivery

The unique properties of chitosan make it a useful choice for various nanoparticulate drug delivery applications. Although chitosan is biocompatible and enables cellular uptake, its interactions at cellular and systemic levels need to be studied in more depth. This review focuses on the various physical and chemical properties of chitosan that affect its performance in biological systems. We aim to analyze recent research studying interactions of chitosan nanoparticles (NPs) upon their cellular uptake and their journey through the various compartments of the cell. The positive charge of chitosan enables it to efficiently attach to cells, increasing the probability of cellular uptake. Chitosan NPs are taken up by cells via different pathways and escape endosomal degradation due to the proton sponge effect. Furthermore, we have reviewed the interaction of chitosan NPs upon in vivo administration. Chitosan NPs are immediately surrounded by a serum protein corona in systemic circulation upon intravenous administration, and their biodistribution is mainly to the liver and spleen indicating RES uptake. However, the evasion of RES system as well as the targeting ability and bioavailability of chitosan NPs can be improved by utilizing specific routes of administration and covalent modifications of surface properties. Ongoing clinical trials of chitosan formulations for therapeutic applications are paving the way for the introduction of chitosan into the pharmaceutical market and for their toxicological evaluation. Chitosan provides specific biophysical properties for effective and tunable cellular uptake and systemic delivery for a wide range of applications.

Innovative topical niosomal gel formulation containing diclofenac sodium (niofenac)

The purpose of this research was to enhance the transdermal delivery of diclofenac sodium niosomal formulations. To characterise the obtained niosomes, SEM, XRPD, DSC and ATR-FTIR were employed. The size of the niosomes increased from 158.00 ± 6.17 to 400.87 ± 4.99 nm when cholesterol was incorporated into the formulations. It was observed that the zeta potential of niofenac varies from -25.40 ± 1.352 to -43.13 ± 1.171 mV when the cholesterol percentage decreased from 2% to 0.2%. The higher entrapment efficiency percentage (63.70 ± 0.18%) was obtained for the formulations with larger particle sizes and higher cholesterol content. The optimised niofenac formulation showed a controlled release fashion where 61.71 ± 0.59% of the drug released within 24 h. The results showed that the value of permeated diclofenac sodium through the skin layers was higher for the niofenac gel formulation (242.3 ± 31.11 µg/cm²) compared to simple gel formulation (127.40 ± 27.80 µg/cm²). Besides, niofenac formulation outperformed the anti-inflammatory activities in the formalin test compared to the control and diclofenac simple gel group. The licking time was significantly lower in both early (40.2 ± 7.3 s) and late stages (432.4 ± 31.7 s) for niofenac compared to conventional formulation (early stage 130.4 ± 8.73 s and late stage 660.6 ± 123.73 s). This study indicates that niosomal formulations can improve drug therapeutic effects by increasing drug delivery to specific sites.

Assessment of Exenatide loaded Biotinylated Trimethylated Chitosan/HP-55 Nanoparticles

BACKGROUND

Exenatide (EXE) is an anti-hyperglycemic agent approved for treating type 2 diabetes by the Food and Drug Administration (FDA). However, twice-daily injection of exenatide inconveniences most patients.

OBJECTIVE

In this study, biotinylated trimethylated chitosan (Bio-TMC) based nanoparticles were proposed to promote oral absorption of exenatide. Realizing the oral administration of exenatide is very important to alleviate patient suffering and improve patient compliance.

METHODS

Bio-TMC was synthesized, and the chemical structure was characterized by Fourier transform infrared (FT-IR) spectroscopy and 1H NMR spectroscopy. Nanoparticles were prepared through polyelectrolyte interaction in the presence of sodium tripolyphosphate (TPP) and Hydroxypropyl methylcellulose phthalate (HP-55). The formulations were physically and chemically characterized. In vitro release was investigated in different pH media. In vivo antidiabetic activities of biotin modified and non-biotin modified chitosan were evaluated in db/db mice.

RESULTS

EXE-loaded Bio-TMC/HP-55 nanoparticles were spherical in shape with a mean diameter of 156.2 nm and zeta potential of +11.3 mV. The drug loading efficiency and loading contents were 52.38% and 2.08%, respectively. In vitro release revealed that EXE-loaded Bio-TMC/HP-55 nanoparticles were released faster in pH 1.2 than pH 6.8 (63.71% vs. 50.12%), indicating that nanoparticles had enteric characteristics. Antidiabetic activity study revealed that after oral administration to diabetic mice, the relative pharmacological bioavailability (FPharm%) of the biotin modified nanoparticles was found to be 1.27-fold higher compared with the unmodified ones and the hypoglycemic effect was also better.

CONCLUSION

Bio-TMC/HP-55 nanoparticles are feasible as oral drug carriers of exenatide and have the potential to be extended to other drugs that are not readily oral, such as monoclonal antibodies, vaccines, genes, etc., thus, this would be beneficial for pharmaceutical industries. Further research will focus on the biodistribution of Bio-TMC/HP-55 nanoparticles after oral administration.

An Overview of Current Knowledge on the Properties, Synthesis and Applications of Quaternary Chitosan Derivatives

Chitosan, a chitin-derivative polysaccharide, known for its non-toxicity, biocompatibility and biodegradability, presents limited applications due to its low solubility in neutral or basic pH medium. Quaternization stands out as an alternative to modify this natural polymer, aiming to improve its solubility over a wide pH range and, consequently, expand its range of applications. Quaternization occurs by introducing a quaternary ammonium moiety onto or outside the chitosan backbone, via chemical reactions with primary amino and hydroxyl groups, under vast experimental conditions. The oldest and most common forms of quaternized chitosan involve N,N,N-trimethyl chitosan (TMC) and N-[(2-hydroxy-3-trimethyl ammonium) propyl] chitosan (HTCC) and, more recently, quaternized chitosan by insertion of pyridinium or phosphonium salts. By modifying chitosan through the insertion of a quaternary moiety, permanent cationic charges on the polysaccharide backbone are achieved and properties such as water solubility, antimicrobial activity, mucoadhesiveness and permeability are significantly improved, enabling the application mainly in the biomedical and pharmaceutical areas. In this review, the main quaternized chitosan compounds are addressed in terms of their structure, properties, synthesis routes and applications. In addition, other less explored compounds are also presented, involving the main findings and future prospects regarding the field of quaternized chitosans.

Quaternary Ammonium Chitosans: The Importance of the Positive Fixed Charge of the Drug Delivery Systems

As a natural polysaccharide, chitosan has good biocompatibility, biodegradability and biosecurity. The hydroxyl and amino groups present in its structure make it an extremely versatile and chemically modifiable material. In recent years, various synthetic strategies have been used to modify chitosan, mainly to solve the problem of its insolubility in neutral physiological fluids. Thus, derivatives with negative or positive fixed charge were synthesized and used to prepare innovative drug delivery systems. Positively charged conjugates showed improved properties compared to unmodified chitosan. In this review the main quaternary ammonium derivatives of chitosan will be considered, their preparation and their applications will be described to evaluate the impact of the positive fixed charge on the improvement of the properties of the drug delivery systems based on these polymers. Furthermore, the performances of the proposed systems resulting from in vitro and ex vivo experiments will be taken into consideration, with particular attention to cytotoxicity of systems, and their ability to promote drug absorption.

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.

Stimulus Responsive Ocular Gentamycin-Ferrying Chitosan Nanoparticles Hydrogel: Formulation Optimization, Ocular Safety and Antibacterial Assessment

PURPOSE

The present study was designed to study the gentamycin (GTM)-loaded stimulus-responsive chitosan nanoparticles to treat bacterial conjunctivitis.

METHODS

GTM-loaded chitosan nanoparticles (GTM-CHNPs) were prepared by ionotropic gelation method and further optimized by 3-factor and 3-level Box-Behnken design. Chitosan (A), sodium tripolyphosphate (B), and stirring speed (C) were selected as independent variables. Their effects were observed on particle size (PS as Y1), entrapment efficiency (EE as Y2), and loading capacity (LC as Y3).

RESULTS

The optimized formulation showed the particle size, entrapment efficiency, and loading capacity of 135.2±3.24 nm, 60.18±1.65%, and 34.19±1.17%, respectively. The optimized gentamycin-loaded chitosan nanoparticle (GTM-CHNPopt) was further converted to the stimulus-responsive sol-gel system (using pH-sensitive carbopol 974P). GTM-CHNPopt sol-gel (NSG5) exhibited good gelling strength and sustained release (58.99±1.28% in 12h). The corneal hydration and histopathology of excised goat cornea revealed safe to the cornea. It also exhibited significant (p<0.05) higher ZOI than the marketed eye drop.

CONCLUSION

The finding suggests that GTM-CHNP-based sol-gel is suitable for ocular delivery to enhance the corneal contact time and improved patient compliance.

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.

Amelioration of Physical Properties and Printability of Paper Coated with N-methylated Chitosan

In offset printing process, poor mechanical properties and printability of paper substrate usually result in printing problems, low quality of print and waste of paper materials. Therefore, many researches focus on the quality improvement of paper substrates using suitable additives. In this work, N-methylated chitosan, including N, N-dimethyl chitosan (DMC) and N, N, N-trimethyl chitosan (TMC), were prepared and employed as coating agents to ameliorate the mechanical properties and printability of paper sheets. Analysis results showed that the mechanical strength of coated papers with DMC and TMC were largely improved, because the fibers with negative charges were prone to form electrostatic bonding with the positively charged N-methylated chitosan, thus enhancing paper strength. Particularly, compared with chitosan and DMC, the TMC-coated paper exhibited better mechanical properties, printability and surface properties due to the high cationic charge density of TMC. Therefore, surface coating with TMC is of great benefit to decrease the printing problem of paper sheets and enhance the operation speed in offset printing. This work provides a valuable reference for the amelioration of the printability and physical properties of high-quality paper products for many promising applications.

Therapeutic Nanoparticles and Their Targeted Delivery Applications

Nanotechnology offers many advantages in various fields of science. In this regard, nanoparticles are the essential building blocks of nanotechnology. Recent advances in nanotechnology have proven that nanoparticles acquire a great potential in medical applications. Formation of stable interactions with ligands, variability in size and shape, high carrier capacity, and convenience of binding of both hydrophilic and hydrophobic substances make nanoparticles favorable platforms for the target-specific and controlled delivery of micro- and macromolecules in disease therapy. Nanoparticles combined with the therapeutic agents overcome problems associated with conventional therapy; however, some issues like side effects and toxicity are still debated and should be well concerned before their utilization in biological systems. It is therefore important to understand the specific properties of therapeutic nanoparticles and their delivery strategies. Here, we provide an overview on the unique features of nanoparticles in the biological systems. We emphasize on the type of clinically used nanoparticles and their specificity for therapeutic applications, as well as on their current delivery strategies for specific diseases such as cancer, infectious, autoimmune, cardiovascular, neurodegenerative, ocular, and pulmonary diseases. Understanding of the characteristics of nanoparticles and their interactions with the biological environment will enable us to establish novel strategies for the treatment, prevention, and diagnosis in many diseases, particularly untreatable ones.

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.

Formulation development and in vitro evaluation of transferrin-conjugated liposomes as a carrier of ganciclovir targeting the retina

Ganciclovir (GCV) is an antiviral drug approved for treatment of cytomegalovirus (CMV) retinitis. It can be delivered to the eye via systemic administrations. However, local delivery of GCV that targets the retina is considered as an alternative to increase efficacy of the treatment and lessen side effects. Thus, this study aimed to develop formulations of transferrin (Tf)-conjugated liposomes containing GCV (Tf-GCV-LPs) for intravitreal injection and topical instillation. Tf-GCV-LPs were prepared by the reverse-phase evaporation technique and then conjugated to Tf. Their physicochemical properties were evaluated. The optimized formulation was selected and subjected to the cytotoxicity test, cellular uptake study in the human retinal pigment epithelial cells (the ARPE-19 cells) and antiviral activity evaluation. The results showed that physicochemical properties of Tf-GCV-LPs were affected by formulation compositions. The optimized Tf-GCV-LPs had a particle size lower than 100 nm with a negative value of zeta potential. They were safe for the ARPE-19 cells. These Tf-GCV-LPs were taken up by these cells via Tf receptors-mediated endocytosis and showed inhibitory activity on CMV in the infected cells. Therefore, the optimized Tf-GCV-LPs could be accepted as a promising drug delivery system for targeted GCV delivery to the retina in the treatment of CMV retinitis.

Physicochemical properties of alpha-mangostin loaded nanomeulsions prepared by ultrasonication technique

Hypothesis

Alpha-mangostin (AMG) is a natural compound possessing strong antibacterial activity. Because of its poor water solubility, the formulations of AMG usually require high concentrations of solubilizers leading limitation for using in some clinical applications. Thus, the novel formulation of topical nanoemulsion (NE) containing AMG (AMG-NE) with optimal content of the oil phase and surfactants was developed.

Experiments

AMG was extracted, purified and used as an active ingredient of AMG-NE. Blank NEs (NEs without AMG) with varying in contents of the oil phase and surfactants and AMG-NE were prepared by the ultrasonication technique. They were investigated their physicochemical properties including antibacterial activity against Staphyloccocus aureus and Propionibacterium acnes (which is recently renamed as Cutibacterium acnes).

Findings

Blank NEs and AMG-NE had droplet size in a range of nanometer and negative value of zeta potential. The droplet size, polydispersity index and zeta potential of blank NEs were affected by formulation compositions and sonication intensities. AMG could be loaded into a representative Blank NE at a maximum concentration of 0.2% w/w and did not cause significant changes in physicochemical properties. AMG-NE showed the antibacterial activity against Staphyloccocus aureus and Propionibacterium acnes without toxicity to the skin cells. Therefore, AMG-NE had potential for using in a clinical study to investigate its efficacy and safety in patients.

Strategies for Improving Ocular Drug Bioavailability and Corneal Wound Healing with Chitosan-Based Delivery Systems

The main inconvenience of conventional eye drops is the rapid washout of the drugs due to nasolacrimal drainage or ophthalmic barriers. The ocular drug bioavailability can be improved by either prolonging retention time in the cul-de-sac or by increasing the ocular permeability. The focus of this review is to highlight some chitosan-based drug delivery approaches that proved to have good clinical efficacy and high potential for use in ophthalmology. They are exemplified by recent studies exploring in-depth the techniques and mechanisms in order to improve ocular bioavailability of the active substances. Used alone or in combination with other compounds with synergistic action, chitosan enables ocular retention time and corneal permeability. Associated with other stimuli-responsive polymers, it enhances the mechanical strength of the gels. Chitosan and its derivatives increase drug permeability through the cornea by temporarily opening tight junctions between epithelial cells. Different types of chitosan-based colloidal systems have the potential to overcome the ocular barriers without disturbing the vision process. Chitosan also plays a key role in improving corneal wound healing by stimulating the migration of keratinocytes when it is used alone or in combination with other compounds with synergistic action.

Development of Yam Dioscorin-Loaded Nanoparticles for Paracellular Transport Across Human Intestinal Caco-2 Cell Monolayers

Dioscorins, the major storage proteins of yam tubers, exert immunomodulatory activities. To improve oral bioavailability of dioscorins in the intestine, recombinant dioscorin (rDioscorin) was coated with N,N,N-trimethyl chitosan (TMC) and tripolyphosphate (TPP), resulting in the formation of TMC-rDio-TPP nanoparticles (NPs). The loading capacity and entrapment efficiency of rDioscorin in the NPs were 26 ± 0.7% and 61 ± 1.4%, respectively. The NPs demonstrated a substantial release profile in the pH environment of the jejunum. The rDioscorin released from the NPs stimulated proliferation and phagocytosis of the macrophage RAW264.7 and activated the gene expression of IL-1β and IL-6. Incubation of the NPs in the Caco-2 cell monolayer led to a 5.2-fold increase of P_app compared with rDioscorin alone, suggesting that rDioscorin, with the assistance of TMC, can be promptly transported across the intestinal epithelia. These results demonstrate that the TMC-rDio-TPP NPs can be utilized for elucidating the immunopharmacological effects of dioscorins through oral delivery.

Current progress and challenges of nanoparticle-based therapeutics in pain management

Pain is a widespread and growing health problem worldwide that exerts a considerable social and economic impact on both patients and healthcare systems and, therefore, on society in general. Although current treatment modalities include a wide variety of pharmacological and non-pharmacological approaches, due to the complexity of pain and individual differences in clinical response these options are not always effective in mitigating and relieving pain. In addition, some pain drugs such as non-steroidal anti-inflammatory drugs (NSAIDs), local anesthetics and opioids show several unfavorable side effects. Therefore, current research advances in this medical field are based on the development of potential treatments to address many of the unmet needs and to overcome the existing limitations in pain management. Nanoparticle drug delivery systems present an exciting opportunity as alternative platforms to improve efficacy and safety of medications currently in use. Herein, we review a broad range of nanoparticle formulations (organic nanostructures and inorganic nanoparticles), which have been developed to encapsulate an array of painkillers, paying special attention to the key advantages that these systems offer, (compared to the use of the free drug), as well as to the more relevant results of preclinical studies in animal models. Additionally, we will briefly discuss the impact of some of these nanoformulations in clinical trials.

Long circulating PEGylated-chitosan nanoparticles of rosuvastatin calcium: Development and in vitro and in vivo evaluations

The aim of this study was to improve the pharmacokinetics and pharmacodynamics profile of rosuvastatin calcium by formulating long-circulating PEGylated chitosan nanoparticles (NPs). Chitosan was PEGylated by a carbodiimide mediated reaction, using a carboxylic acid derivative of PEG (polyethylene glycol). The NPs were optimised for particle size, polydispersity index, zeta potential and drug entrapment efficiency. In vitro drug release, pharmacokinetic and pharmacodynamics studies of the optimized nanoparticles were performed. PEGylation of chitosan was confirmed by FTIR analysis. Drug-excipient compatibility was studied by differential scanning calorimetry and FTIR analyses. Two batches of nanoparticles were optimized with particle size of <200nm and entrapment efficiency of ≈14%. In vitro drug release studies revealed cumulative release of 14.07±0.57% and 22.02±0.81% of rosuvastatin over the period of 120h, indicating appreciable sustained release of drug. TEM analysis showed the spherical structure of nanoparticles. Pharmacokinetic studies indicated that optimized NPs showed prolonged drug release over a period of 72h. Pharmacodynamics studies in hyperlipidemic rat model demonstrated greater lipid-lowering capability of rosuvastatin nanoparticles in comparison with plain rosuvastatin. The nanoparticles demonstrated substantial prolonged delivery of the drug in vivo along with better therapeutic action, which could be potential drug delivery modality for 'statins'.

Nanotechnology: from In Vivo Imaging System to Controlled Drug Delivery

Science and technology have always been the vitals of human's struggle, utilized exclusively for the development of novel tools and products, ranging from micro- to nanosize. Nanotechnology has gained significant attention due to its extensive applications in biomedicine, particularly related to bio imaging and drug delivery. Various nanodevices and nanomaterials have been developed for the diagnosis and treatment of different diseases. Herein, we have described two primary aspects of the nanomedicine, i.e., in vivo imaging and drug delivery, highlighting the recent advancements and future explorations. Tremendous advancements in the nanotechnology tools for the imaging, particularly of the cancer cells, have recently been observed. Nanoparticles offer a suitable medium to carryout molecular level modifications including the site-specific imaging and targeting. Invention of radionuclides, quantum dots, magnetic nanoparticles, and carbon nanotubes and use of gold nanoparticles in biosensors have revolutionized the field of imaging, resulting in easy understanding of the pathophysiology of disease, improved ability to diagnose and enhanced therapeutic delivery. This high specificity and selectivity of the nanomedicine is important, and thus, the recent advancements in this field need to be understood for a better today and a more prosperous future.

Intranasal administration of brain-targeted HP-β-CD/chitosan nanoparticles for delivery of scutellarin, a compound with protective effect in cerebral ischaemia

OBJECTIVES

Scutellarin (SCU) is a traditional Chinese medicine used for the treatment of ischaemic cerebrovascular disease, but its clinic applications have been limited due to its poor water solubility, poor bioavailability and short half-life. In comparison with the conventional oral and intravenous administration, nasal administration may help targeting the drug more directly to brain. Thus, we proposed to employ a novel SCU-loaded HP-β-CD/chitosan nanoparticles (CD/CS-SCU-NPs) to deliver SCU to brain through the nasal route.

METHODS

CD/CS-SCU-NPs were prepared by an ionic cross-linking method. The NPs formulation was tested in vivo in C57BL mice. The concentrations of SCU in brain and plasma after intranasal and oral administration of the CD/CS-SCU-NPs and after intranasal administration of SCU solution (SCU-SL) were determined and brain targeting parameters were calculated.

KEY FINDINGS

Compared to the intranasal administration of SCU-SL, intranasal and oral administration of the CD/CS-SCU-NPs increased accumulation of SCU in brain, indicating that CD/CS-SCU-NPs have obvious brain targeting advantage, although the advantage is more evident after intranasal administration.

CONCLUSIONS

Findings from in-vivo study indicated that much higher SCU brain exposure was observed after intranasal administration of the CD/CS-SCU-NPs. Administration of CD/CS-SCU-NPs through the nasal route would have potential to treat ischemic cerebrovascular disease.

Formulation optimization of scutellarin-loaded HP-β-CD/chitosan nanoparticles using response surface methodology with Box-Behnken design

The aim of this paper is to investigate and optimize the preparation of scutellarin (SCU)-loaded HP-β-CD/chitosan (CS) nanoparticles (CD/CS-SCU-NPs). CD/CS-SCU-NPs were prepared by ionic cross-linking method and the process and formulation variables were optimized using response surface methodology (RSM) with a three-level, three factor Box–Behnken design (BBD). The independent variables were the added amounts of CS, sodium tripolyphosphate (TPP) and Pluronic F-68 during the preparation. Dependent variables (responses) were particle size and entrapment efficiency. Mathematical equations and respond surface plots were used to correlate independent and dependent variables. The preparation process and formulation variables were optimized to achieve minimum particle size and maximum entrapment efficiency by calculating the overall desirability value (OD). The optimized NP formulation was characterized for particle size, PDI, zeta potential, entrapment efficiency and in vitro drug release. According to the results, an optimized CD/CS-SCU-NP formulation was prepared. Results for particle size, PDI, zeta potential and entrapment efficiency were found to be around 200 nm, 0.5, 25 mV, and 70% respectively. For in vitro study, the release of SCU from the NPs exhibited a biphasic release and was in accordance with Higuchi equation. The optimized preparation was simple with the probability for industrialization. The combination use of RSM, BBD and overall desirability values could provide a promising application for incorporating CD into CS nanoparticles as drug delivery carrier and help develop lab-scale procedures.

A novel ion-exchange carrier based upon liposome-encapsulated montmorillonite for ophthalmic delivery of betaxolol hydrochloride

As a novel ion-exchange carrier with high surface area and excellent exchangeability, montmorillonite (Mt) was intercalated with betaxolol hydrochloride (BH) to form a nanocomposite and then encapsulated by liposomes (Mt-BH-LPs) for an ophthalmic drug-delivery system. The Mt-BH and Mt-BH-LPs were prepared by an acidification process and ethanol injection combined with ammonium sulfate gradient methods. The successful formation of Mt-BH and Mt-BH-LPs was verified by thermogravimetric analysis, X-ray diffraction, Fourier-transform infrared spectra, and transmission electron microscopy. Mt-BH-LPs possessed the favorable physical characteristics of encapsulation efficiency, drug loading, mean particle size, and ζ-potential. In vitro release studies indicated Mt-BH-LPs effectively maintained a relatively sustained slow release. Immortalized human corneal epithelial cell cytotoxicity, in vivo rabbit eye-irritation tests, and chorioallantoic membrane–trypan blue staining all revealed that Mt-BH-LPs had no obvious irritation on ocular tissues. A new in vitro tear-turnover model, including inserts containing human corneal epithelial cells, was designed to evaluate the precorneal retention time of Mt-BH-LPs. The results showed that Mt-BH-LPs maintained a certain BH concentration in tear fluid for a longer period than the BH solution. In vivo precorneal retention studies also indicated Mt-BH-LPs prolonged drug retention on the ocular surface more than the BH solution. Furthermore, pharmacodynamic studies showed that Mt-BH-LPs had a prolonged effect on decreasing intraocular optical pressure in rabbits. Our results demonstrated that Mt-BH-LPs have potential as an ophthalmic delivery system.

Gamma sterilization of diclofenac sodium loaded- N-trimethyl chitosan nanoparticles for ophthalmic use

This study was conducted to investigate the effect of gamma irradiation on physicochemical properties of N-trimethyl chitosan (TMC), diclofenac sodium (DC) and diclofenac sodium loaded N-trimethylchitosan nanoparticles (DC-TMCNs), and to determine suitable doses of gamma rays for sterilization of DC-TMCNs. Physicochemical properties of TMC, DC and DC-TMCNs before and after exposure to gamma rays at various doses were investigated. It was found that gamma irradiation at doses of 5-25kGy did not cause any significant changes in physical and chemical properties of TMC, DC and DC-TMCNs. The bioburden of DC-TMCNs was 1.5×10⁶ CFU/vial. The initial contaminating bacteria were radiosensitive bacteria. A number of microorganisms was reduced to 10^-6 after exposure to 9.9kGy of gamma rays. Therefore, DC-TMCNs could be sterilized by gamma irradiation at a dose of 10kGy, which did not alter their physicochemical properties and did not produce any substances toxic to the eye.

Alkyl cross-linked low molecular weight polypropyleneimine dendrimers as efficient gene delivery vectors

OBJECTIVES

In recent years, polypropyleneimine (PPI) dendrimers have attracted great interest as non-viral gene delivery systems because of their attractive features including highly branched architecture with number of reactive end groups. However, without being structurally modified, they are not efficient gene carriers. In the present study, generation 2 and 3 (G2 and G3) of PPI dendrimers were conjugated with alkylcarboxylate groups as linker to enhance the transfection efficiency while maintaining their low cell toxicity.

MATERIALS AND METHODS

First, 10-bromodecanoic acid was covalently attached to all available surface primary amines of PPI G2 and G3 to increase their lipophilicity. In the subsequent step, PPIs were conjugated to the alkylcarboxylate groups of alkylcarboxylate-PPI derivatives to increase the number of surface primary amines. Physicochemical properties of modified PPIs were determined. Transfection experiments (using both luciferase and green fluorescent protein (GFP)- expressing plasmids) and cytotoxicity assay were performed to evaluate the efficiency of the final derivatives.

RESULTS

Fabricated vectors condensed DNA effectively so that polyplexes with appropriate size (below 155 nm) and positive surface charge were constructed. Cross-linked low molecular weight PPIs (G2 or G3) with decanoate linkage increased transfection efficiency significantly while maintaining the low cytotoxicity. PPI G2 derivative exhibited increased buffering capacity which is believed to be responsible for better proton sponge mechanism leading to higher transfection efficiency.

CONCLUSION

Our results indicated that oligomerization of low molecular weight PPI (PPI G2-alkyl-PPI G2 conjugate) could be an approach to increase the transfection efficiency and to lower the cytotoxicity of low molecular weight polycations.

Ocular delivery of cyanidin-3-glycoside in liposomes and its prevention of selenite-induced oxidative stress

CONTEXT

Cataracts have become the leading cause of blindness around the world, which is mainly mediated by oxidative stress.

OBJECTIVE

N-trimethyl chitosan (TMC)-coated liposomes of cyanidin-3-glycoside (C3G) (C3G-TCL) were prepared to attenuate oxidative stress induced by selenite sodium in rats.

MATERIALS AND METHODS

C3G-TCL were prepared by reverse-phase evaporation method and then coated with self-synthesized TMC. The physicochemical properties were determined. A gamma-scintigraphy study was employed to evaluate the precorneal elimination of the radioactive preparations. The transcorneal visualization for fluorescence-labeled samples was determined by confocal laser scanning microscopy (CLSM). The in vivo anti-oxidative study using C3G-TCL was carried out in rats with selenite-induced cataracts by topical administration.

RESULTS

The sphere-like morphological characterization of the vesicles was confirmed by TEM, with a size of 158.3 ± 2.8 nm and a zeta potential of 31.7 mV. The encapsulation efficiency was (53.7 ± 0.2) % as measured by ultrafiltration. C3G-TCL showed a 3.3-fold increment in precorneal residence time when compared with that of the (99m)Tc-solution. A TMC coating enhanced the transepithelial transport of liposomes to a depth of 40-μm in the cornea. Moreover, C3G-TCL could significantly elevate the activity of superoxide dismutase and catalase in lens and also show a considerable reversal of reduced glutathione activity. The lipid peroxidation in lens was strongly prevented when compared with that of groups treated with uncoated C3G-loaded liposomes.

DISCUSSION AND CONCLUSION

The coating material TMC for liposomes helps improve the anti-oxidative effect of C3G in vivo through prolonged residence time on the cornea and improved permeability in the corneal epithelium.