Development of besifloxacin HCl loaded nanofibrous ocular inserts for the treatment of bacterial keratitis: In vitro, ex vivo and in vivo evaluation

Microtubular and high porosity design of electrospun PEGylated poly (lactic-co-glycolic acid) fibrous implant for ocular multi-route administration and medication

Electrospun fibers have been gaining popularity in ocular drug delivery and cellular therapies. However, most of electrospun fibers are planar-shape membrane with large dimension relative to intraocular space, making difficult to use as therapeutic implants. Herein, fibrous microtubes with a hollow center were fabricated by electrospinning using linear diblock mPEG2000-PLGA. Uniform microfibers with 0.809 μm diameter was tailored using Box-Behnken Design model for electrospinning process optimization. The microtubes were 1 mm long with a 0.386 mm diameter. Their suitability for intraocular administration was demonstrated by both injection via a 22-gauge needle and implant via integration of intraocular lens into the vitreous or anterior chamber of eyes, respectively. Electrospun mPEG2000-PLGA had higher porosity, smaller specific surface area, and smaller water contact angle, than that of PLGA. Macroscopically, mPEG2000-PLGA microfibers can maintain overall geometry upon exposure to aqueous buffer for 12 h while having high water uptake and exhibited good elasticity. Hydrolysis with 90 % polymeric degradation in 10.5 weeks underlied sustained slow release of anti-inflammatory drug dexamethasone. PEGylation of PLGA imparted preferential cell adhesion with markedly higher growth of human retinal epithelial cells than lens epithelial ones. This study highlights the potential utility of implantable electrospun PLGA-based microtubes for multiple intraocular delivery routes.

Oriented cellulose hydrogel: Directed tissue regeneration for reducing corneal leukoplakia and managing fungal corneal ulcers

Fungal corneal ulcer is one of the leading causes of corneal blindness in developing countries. Corneal scars such as leukoplakia are formed due to inflammation, oxidative stress and non-directed repair, which seriously affect the patients' subsequent visual and life quality. In this study, drawing inspiration from the oriented structure of collagen fibers within the corneal stroma, we first proposed the directional arrangement of CuTA-CMHT hydrogel system at micro and macro scales based on the 3D printing extrusion method combined with secondary patterning. It played an antifungal role and induced oriented repair in therapy of fungal corneal ulcer. The results showed that it effectively inhibited Candida albicans, Aspergillus Niger, Fusarium sapropelum, which mainly affects TNF, NF-kappa B, and HIF-1 signaling pathways, achieving effective antifungal functions. More importantly, the fibroblasts interacted with extracellular matrix (ECM) of corneal stroma through formation of focal adhesions, promoted the proliferation and directional migration of cells in vitro, induced the directional alignment of collagen fibers and corneal stromal orthogonally oriented repair in vivo. This process is mainly associated with MYLK, MYL9, and ITGA3 molecules. Furthermore, the downregulation the growth factors TGF-β and PDGF-β inhibits myofibroblast development and reduces scar-type ECM production, thereby reducing corneal leukoplakia. It also activates the PI3K-AKT signaling pathway, promoting corneal healing. In conclusion, the oriented CuTA-CMHT hydrogel system mimics the orthogonal arrangement of collagen fibers, inhibits inflammation, eliminates reactive oxygen species, and reduces corneal leukoplakia, which is of great significance in the treatment of fungal corneal ulcer and is expected to write a new chapter in corneal tissue engineering.

Formulation and Development of Nanofiber-Based Ophthalmic Insert for the Treatment of Bacterial Conjunctivitis

A novel ophthalmic delivery system utilizing levofloxacin-loaded, preservative-free, nanofiber-based inserts was investigated. Polyvinyl alcohol (PVA) and Poloxamer 407 (Polox)were employed as matrix materials, while hydroxypropyl-beta-cyclodextrin (HP-β-CD) was a solubilizer. The formulations were prepared via electrospinning and characterized for fiber morphology, drug dissolution, cytotoxicity, and antimicrobial activity. Scanning electron microscopy confirmed uniform fibrous structures. Fourier Transform Infrared spectroscopy and X-ray diffraction analyses demonstrated the amorphous state of levofloxacin within the fibers. In vitro dissolution studies revealed a rapid (within 2 min) and complete drug release, with higher HP-β-CD levels slightly delaying the release. Cytotoxicity tests showed increased HP-β-CD concentrations induced irritation, that was mitigated by sodium hyaluronate. The antimicrobial efficacy of the nanofibers was comparable to conventional eye drops, with lower minimum inhibitory concentrations for most tested strains. The nanofibrous formulation prepared from a PVA-Polox-based viscous solution of the drug:CD 1:1 mol ratio, containing 0.4% (w/w) sodium hyaluronate) was identified as a particularly promising alternative formulation due to its rapid and complete dissolution, good biocompatibility, and effective antimicrobial properties. Its gelling properties indicate that the residence time on the eye surface can be increased, potentially reducing discomfort and enhancing therapeutic outcomes. The nanofibrous formulations enhanced antimicrobial efficacy, providing a preservative-free alternative that minimizes the potential eye irritation that might occur because of the preservative agent and reduces the administrated dose frequency by extending the drug's retention time on the eye's surface. Subsequently, it improves patients' adherence, which would reflect positively on the bioavailability. The levofloxacin-HP-β-CD nanofibers demonstrate promise as an alternative to traditional eye drops, offering advantages in solubility, stability, and patient compliance for ocular infection treatment.

Formulation of hesperidin-loaded in situ gel for ocular drug delivery: a comprehensive study

BACKGROUND

Allergic conjunctivitis is one of the most common eye disorders. Different drugs are used for its treatment. Hesperidin is an active substance isolated from Citrus sinensis L. (Rutaceae) fruit peels, with known anti-inflammatory activity but low solubility. It was complexed with cyclodextrin and encapsulated in situ gel to extend its duration in the eye.

RESULTS

The optimized formulation comprised 1% hesperidin, 1.5% hydroxyethyl cellulose, and 16% poloxamer 407. The viscosity at 25 °C was 492 ± 82 cP, and at 35 °C it was 8875 ± 248 cP, the pH was 7.01 ± 0.03, gelation temperature was 34 ± 1.3 °C, and gelation time was 33 ± 1.2 s. There was a 66% in vitro release in the initial 2 h, with a burst effect. A lipoxygenase (LOX) inhibition test determined that hesperidin was active at high doses on leukotyrens seen in the body in allergic diseases. In cell-culture studies, the hesperidin cyclodextrin complex loaded in situ gel, BRN9-CD (poloxamer 16%, hydroxy ethyl cellulose (HEC) 1.5%), enhanced cell viability in comparison with the hesperidin solution. It was determined that BRN9-CD did not cause any irritation in the ocular tissues in the Draize test.

CONCLUSION

The findings of this study demonstrate the potential of the in situ gel formulation of hesperidin in terms of ease of application and residence time on the ocular surface. Due to its notable LOX inhibition activity and positive outcomes in the in vivo Draize test, it appears promising for incorporation into pharmaceutical formulations. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Synthetic and Natural Biomaterials in Veterinary Medicine and Ophthalmology: A Review of Clinical Cases and Experimental Studies

In recent years, there has been a growing interest in 3D printing technology within the field of bioengineering. This technology offers the ability to create devices with intricate macro- and micro-geometries, as well as specific models. It has particularly gained attention for its potential in personalized medicine, allowing for the production of organ or tissue models tailored to individual patient needs. Further, 3D printing has opened up possibilities to manufacture structures that can substitute, complement, or enhance damaged or dysfunctional organic parts. To apply 3D printing in the medical field, researchers have studied various materials known as biomaterials, each with distinct chemical and physical characteristics. These materials fall into two main categories: hard and soft materials. Each biomaterial needs to possess specific characteristics that are compatible with biological systems, ensuring long-term stability and biocompatibility. In this paper, we aim to review some of the materials used in the biomedical field, with a particular focus on those utilized in veterinary medicine and ophthalmology. We will discuss the significant findings from recent scientific research, focusing on the biocompatibility, structure, applicability, and in vitro and in vivo biological characteristics of two hard and four soft materials. Additionally, we will present the current state and prospects of veterinary ophthalmology.

Development and Evaluation of Different Electrospun Cysteamine-Loaded Nanofibrous Webs: A Promising Option for Treating a Rare Lysosomal Storage Disorder

Nanofibers can be utilized to overcome the challenges faced by conventional ophthalmic formulations. This study aimed to develop and characterize cysteamine (Cys)-loaded nanofiber-based ophthalmic inserts (OIs) as a potential candidate for the treatment of ophthalmic cystinosis using water-soluble polyvinyl alcohol (PVA)/poloxamer 407 (PO-407) and water-insoluble tetraethoxysilane (TEOS)/PVA nanofibers. Plain and Cys-loaded fibers in different proportions were prepared by the electrospinning method and studied for their morphological, physicochemical, release study, cytocompatibility effects, and stability study. The fiber formation was confirmed by scanning electron microscopy, while Fourier transform infrared spectra showed the most critical peaks for the Cys and the excipients. The release of the Cys was fast from the two polymeric matrices (≤20 min). The release from TEOS/PVA nanofibers is characterized by Case II transport (0.75 < β < 1), while the release from PVA/PO-407 nanofibers follows Fickian diffusion (β < 0.75). The cytocompatibility of compositions was confirmed by hen eggs tested on the chorioallantoic membrane (HET-CAM) of chick embryos. All formulations remained stable under stress conditions (40 ± 2 °C, 75 ± 5% relative humidity) regarding morphology and physicochemical characteristics. The developed nanofibrous mats could be an excellent alternative to available Cys drops, with better stability and convenience of self-administration as OIs.

Gingerol containing polymeric nanofibers: a healing touch for accelerated wound recovery

OBJECTIVE

In the current research, 6-gingerol (GA)-loaded nanofiber drug delivery system were developed, and their potential usage in wound healing was evaluated.

SIGNIFICANCE

This study investigates the effectiveness of nanofibrous membranes composed of sodium alginate (SA), poly(vinyl alcohol) (PVA), and 6-gingerol (GA) as delivery systems for anti-inflammatory agents in the context of wound dressings.

METHODS

GA-loaded SA/PVA nanofiber was prepared using electrospinning. In vitro characterization of this nanofiber included the examination of comprehensive in vitro characterization, anti-inflammatory and antioxidant activities, cytotoxicity, a scratch tes and in vivo skin test.

RESULTS

GA was extracted from Zingiber officinale, and its successful isolation was confirmed through analyses such as H-NMR, C-NMR. Then GA was electrospuned into the SA/PVA nanofibers, and scanning electron microscopy (SEM) imaging revealed that the fiber diameters of the formulations ranged between 148 nm and 176 nm. Anti-inflammatory and antioxidant studies demonstrated that the effectiveness of GA increased with higher doses; however, this increase was accompanied by decreased cell viability. In vitro release studies revealed that GA exhibited a burst release within the first 8 h, followed by a controlled release, reaching completion within 24 h. Within the scope of in vitro release kinetics, release data are mathematically compatible with the Weibull model with high correlation. The scratch test results indicated that TB2 (%1 GA) promoted epithelialization. Furthermore, it was determined that TB2 (%1 GA) did not cause any irritation.

CONCLUSIONS

As a result, TB2 shows promise as a formulation for wound dressings, offering potential benefits in the field of wound care.

Design and development of dual drug-loaded nanofibrous inserts for ophthalmic sustained delivery of AMK and VAN: Pharmacokinetic study in rabbit's eye

Bacterial corneal keratitis is a damage to the corneal tissue that if not treated, can cause various complications like severe vision loss or even blindness. Combination therapy with two antibiotics which are effective against Gram-positive and Gram-negative bacteria offers sufficient broad-spectrum antibiotic coverage for the treatment of keratitis. Nanofibers can be a potential carrier in dual drug delivery due to their structural characteristics, specific surface area and high porosity. In order to achieve a sustained delivery of amikacin (AMK) and vancomycin (VAN), the current study designed, assessed, and compared nanofibrous inserts utilizing polyvinyl alcohol (PVA) and polycaprolactone (PCL) as biocompatible polymers. Electrospinning method was utilized to prepare two different formulations, PVA-VAN/AMK and PCL/PVA-VAN/AMK, with 351.8 ± 53.59 nm and 383.85 ± 49 nm diameters, respectively. The nanofibers were simply inserted in the cul-de-sac as a noninvasive approach for in vivo studies. The data obtained from the physicochemical and mechanical properties studies confirmed the suitability of the formulations. Antimicrobial investigations showed the antibacterial properties of synthesized nanofibers against Staphylococcus aureus and Pseudomonas aeruginosa. Both in vitro and animal studies demonstrated sustained drug release of the prepared nanofibers for 120 h. Based on the in vivo findings, the prepared nanofibers' AUC0-120 was found to be 20 to 31 times greater than the VAN and AMK solutions. Considering the results, the nanofibrous inserts can be utilized as an effective and safe system in drug delivery.

An insight on ophthalmic drug delivery systems: Focus on polymeric biomaterials-based carriers

Presently, different types of eye diseases, such as glaucoma, myopia, infection, and dry eyes are treated with topical eye drops. However, due to ocular surface barriers, eye drops require multiple administrations, which may cause several risks, thereby necessitating additional strategies. Some of the key characteristics of an ideal ocular drug delivery system are as follows: (a) good penetration into cornea, (b) high drug retention in the ocular tissues, (c) targetability to the desired regions of the eye, and (d) good bioavailability. It is worthy to note that the corneal epithelial tight junctions hinder the permeation of therapeutics through the cornea. Therefore, it is necessary to design nanocarriers that can overcome these barriers and enhance drug penetration into the inner parts of the eye. Moreover, intelligent multifunctional nanocarriers can be designed to include cavities, which may help encapsulate sufficient amount of the drug. In addition, nanocarriers can be modified with the targeting moieties. Different types of nanocarriers have been developed for ocular drug delivery applications, including emulsions, liposomes, micelles, and nanoparticles. However, these formulations may be rapidly cleared from the eye. The therapeutic use of the nanoparticles (NPs) is also hindered by the non-specific adsorption of proteins on NPs, which may limit their interaction with the cellular moieties or other targeted biological factors. Functional drug delivery systems (DDS), which can offer targeted ocular drug delivery while avoiding the non-specific protein adsorption could exhibit great potential. This could be further realized by the on-demand DDS, which can respond to the stimuli in a spatio-temporal fashion. The cell-mediated DDS offer another valuable platform for ophthalmological drug delivery.

Formulation development of Lornoxicam loaded heat triggered ocular in-situ gel using factorial design

OBJECTIVE

In the current research, lornoxicam-loaded in situ gels were developed, and their potential usage in ocular inflammation was evaluated.

SIGNIFICANCE

Lornoxicam cyclodextrin complex prepared with hydroxypropyl methylcellulose and poloxamer P407 because of the low viscosity of in situ gels to provide easy application. However, washing and removing it from the ocular surface becomes difficult due to the gelation formation with heat.

METHODS

A three-level factorial experimental design was used to evaluate the effects of poloxamer 407 concentration, polymer type, and polymer concentration on viscosity, pH, gelation capacity, gelation time, and gelation temperature, which were considered the optimal indicators of lornoxicam-containing formulations.

RESULTS

As a result of the three-level factorial experimental design, the optimized formulation contained 15 (%w/v) poloxamer 407 and 1 (%w/v) hydroxypropyl methylcellulose. The optimize formulation viscosity 25 °C = 504 ± 49cP, viscosity 35 °C = 11247 ± 214cP, pH = 6.80 ± 0.01, gelation temprature = 35 ± 0.2 °C, and gelation time= 34 ± 0.2 s was obtained. In the in vitro release studies, 68% of lornoxicam was released with a burst effect in the first three hours; then, the release continued for eight hours with controlled release. Release kinetics of the formulations were modeled mathematically, and it was found to be compatible with the Korsemeyer-Peppas and Weibull models. In cell culture studies, cell viability at 100 µg/mL was 83% and 96% for NL6 and NL6-CD, respectively. In Draize's in vivo test, no negative conditions occurred in rats.

CONCLUSIONS

Therefore, the NL6-CD formulation has the potential to be a favorable option for treating ocular inflammation.

In Vitro and Ex Vivo Models for Assessing Drug Permeation across the Cornea

Drug permeation across the cornea remains a major challenge due to its unique and complex anatomy and physiology. Static barriers such as the different layers of the cornea, as well as dynamic aspects such as the constant renewal of the tear film and the presence of the mucin layer together with efflux pumps, all present unique challenges for effective ophthalmic drug delivery. To overcome some of the current ophthalmic drug limitations, the identification and testing of novel drug formulations such as liposomes, nanoemulsions, and nanoparticles began to be considered and widely explored. In the early stages of corneal drug development reliable in vitro and ex vivo alternatives, are required, to be in line with the principles of the 3Rs (Replacement, Reduction, and Refinement), with such methods being in addition faster and more ethical alternatives to in vivo studies. The ocular field remains limited to a handful of predictive models for ophthalmic drug permeation. In vitro cell culture models are increasingly used when it comes to transcorneal permeation studies. Ex vivo models using excised animal tissue such as porcine eyes are the model of choice to study corneal permeation and promising advancements have been reported over the years. Interspecies characteristics must be considered in detail when using such models. This review updates the current knowledge about in vitro and ex vivo corneal permeability models and evaluates their advantages and limitations.

Nanofibers in Ocular Drug Targeting and Tissue Engineering: Their Importance, Advantages, Advances, and Future Perspectives

Nanofibers are frequently encountered in daily life as a modern material with a wide range of applications. The important advantages of production techniques, such as being easy, cost effective, and industrially applicable are important factors in the preference for nanofibers. Nanofibers, which have a broad scope of use in the field of health, are preferred both in drug delivery systems and tissue engineering. Due to the biocompatible materials used in their construction, they are also frequently preferred in ocular applications. The fact that they have a long drug release time as a drug delivery system and have been used in corneal tissue studies, which have been successfully developed in tissue engineering, stand out as important advantages of nanofibers. This review examines nanofibers, their production techniques and general information, nanofiber-based ocular drug delivery systems, and tissue engineering concepts in detail.

Core-Shell Polyvinyl Alcohol (PVA) Base Electrospinning Microfibers for Drug Delivery

In this study, electrospun membranes were developed for controlled drug release applications. Both uniaxial Polyvinyl alcohol (PVA) and coaxial fibers with a PVA core and a poly (L-lactic acid) (PLLA) and polycaprolactone (PCL) coating were produced with different coating structures. The best conditions for the manufacture of the fibers were also studied and their morphology was analyzed as a function of the electrospinning parameters. Special attention was paid to the fiber surface morphology of the coaxial fibers, obtaining both porous and non-porous coatings. Bovine serum albumin (BSA) was used as the model protein for the drug release studies and, as expected, the uncoated fibers were determined to have the fastest release kinetics. Different release rates were obtained for the coated fibers, which makes this drug release system suitable for different applications according to the release time required.

Overview of Side-Effects of Antibacterial Fluoroquinolones: New Drugs versus Old Drugs, a Step Forward in the Safety Profile?

Antibacterial fluoroquinolones (FQs) are frequently used in treating infections. However, the value of FQs is debatable due to their association with severe adverse effects (AEs). The Food and Drug Administration (FDA) issued safety warnings concerning their side-effects in 2008, followed by the European Medicine Agency (EMA) and regulatory authorities from other countries. Severe AEs associated with some FQs have been reported, leading to their withdrawal from the market. New systemic FQs have been recently approved. The FDA and EMA approved delafloxacin. Additionally, lascufloxacin, levonadifloxacin, nemonoxacin, sitafloxacin, and zabofloxacin were approved in their origin countries. The relevant AEs of FQs and their mechanisms of occurrence have been approached. New systemic FQs present potent antibacterial activity against many resistant bacteria (including resistance to FQs). Generally, in clinical studies, the new FQs were well-tolerated with mild or moderate AEs. All the new FQs approved in the origin countries require more clinical studies to meet FDA or EMA requirements. Post-marketing surveillance will confirm or infirm the known safety profile of these new antibacterial drugs. The main AEs of the FQs class were addressed, highlighting the existing data for the recently approved ones. In addition, the general management of AEs when they occur and the rational use and caution of modern FQs were outlined.

Innovation in the Development of Synthetic and Natural Ocular Drug Delivery Systems for Eye Diseases Treatment: Focusing on Drug-Loaded Ocular Inserts, Contacts, and Intraocular Lenses

Nowadays, ocular drug delivery still remains a challenge, since the conventional dosage forms used for anterior and posterior ocular disease treatments, such as topical, systemic, and intraocular administration methods, present important limitations mainly related to the anatomical complexity of the eye. In particular, the blood-ocular barrier along with the corneal barrier, ocular surface, and lacrimal fluid secretion reduce the availability of the administered active compounds and their efficacy. These limitations have increased the need to develop safe and effective ocular delivery systems able to sustain the drug release in the interested ocular segment over time. In the last few years, thanks to the innovations in the materials and technologies employed, different ocular drug delivery systems have been developed. Therefore, this review aims to summarize the synthetic and natural drug-loaded ocular inserts, contacts, and intraocular lenses that have been recently developed, emphasizing the characteristics that make them promising for future ocular clinical applications.

Overview of Antimicrobial Biodegradable Polyester-Based Formulations

As the clinical complications induced by microbial infections are known to have life-threatening side effects, conventional anti-infective therapy is necessary, but not sufficient to overcome these issues. Some of their limitations are connected to drug-related inefficiency or resistance and pathogen-related adaptive modifications. Therefore, there is an urgent need for advanced antimicrobials and antimicrobial devices. A challenging, yet successful route has been the development of new biostatic or biocide agents and biomaterials by considering the indisputable advantages of biopolymers. Polymers are attractive materials due to their physical and chemical properties, such as compositional and structural versatility, tunable reactivity, solubility and degradability, and mechanical and chemical tunability, together with their intrinsic biocompatibility and bioactivity, thus enabling the fabrication of effective pharmacologically active antimicrobial formulations. Besides representing protective or potentiating carriers for conventional drugs, biopolymers possess an impressive ability for conjugation or functionalization. These aspects are key for avoiding malicious side effects or providing targeted and triggered drug delivery (specific and selective cellular targeting), and generally to define their pharmacological efficacy. Moreover, biopolymers can be processed in different forms (particles, fibers, films, membranes, or scaffolds), which prove excellent candidates for modern anti-infective applications. This review contains an overview of antimicrobial polyester-based formulations, centered around the effect of the dimensionality over the properties of the material and the effect of the production route or post-processing actions.

Formulation development and in Vitro-Ex vivo characterization of hot-melt extruded ciprofloxacin hydrochloride inserts for ocular applications: Part I

This study developed, optimized, characterized, and evaluated bioadhesive, hot-melt extruded (HME), extended-release ocular inserts containing ciprofloxacin hydrochloride (CIP-HCL) to improve the therapeutic outcomes of ocular bacterial infections. The inserts were fabricated with FDA-approved biocompatible, biodegradable, and bioadhesive polymers that were tuned in different ratios to achieve a sustained release profile. The results revealed an inverse relationship between the Klucel™ hydroxypropyl cellulose (HPC, 140,000 Da) concentration and drug release and extended-release profile over 24 h. The CIP-HCL-HME inserts presented stable drug content, thermal behavior, surface pH, and release profiles over three months of room-temperature storage and demonstrated adequate mucoadhesive strength. SEM micrographs revealed a smooth surface. Bacterial growth was not observed on the samples during the in vitro release experiment (0.5-24 h), indicating that a minimum inhibitory concentration (MIC) of 90 against Pseudomonas aeruginosa was achieved. Ex vivo transcorneal permeation studies using excised rabbit corneas revealed that the prepared ocular inserts prolonged the transcorneal flux of the drug compared to commercial eye drops and immediate-release inserts and could reduce the administration frequency to once daily. Therefore, the inserts could increase patient compliance and exhibited prolonged antibacterial activity and thus could provide better therapeutic outcomes against ocular bacterial infections.

A Literature-Based Review and Analysis of the Pharmacodynamics of the Dose Frequency of Topical 0.3% Ciprofloxacin and 0.3% Ofloxacin in the Day-1 Treatment of Bacterial Keratitis

Purpose: To determine the appropriate dose frequency for the second-generation fluoroquinolones (2FQs), ciprofloxacin 0.3% and ofloxacin 0.3%, in the day-1 treatment of bacterial keratitis (BK) based on the corneal concentrations achievable and required Minimum Inhibitory Concentration₉₀ (MIC₉₀) of common BK isolates. Methods: Literature-based ocular MIC₉₀ required to treat bacterial isolates of BK patients were determined for each fluoroquinolone. Published corneal concentrations for each 2FQ, and the drop regimens used to reach these concentrations, were then analyzed to determine the relationship between the corneal 2FQ concentration and the amount of drug applied per hour and the total amount applied. Results: Significant relationships were found to exist for corneal concentrations of both ciprofloxacin and ofloxacin and the amount of drug applied per hour (both P = 0.005), and the total amount of drug applied (P = 0.003 and P = 0.0004, respectively). Derived ciprofloxacin drops/hour corneal concentrations agreed well with both a literature-based regimen and the manufacturers' day-1 drop regimen for various MIC₉₀. Derived ofloxacin drops per hour indicated a higher rate than that suggested by the manufacturer. Conclusions: Both a literature-based and the manufacturers' drop regimens for the day-1 treatment of BK using 0.3% ciprofloxacin have a pharmacodynamic basis, which is related to the required MIC₉₀ of commonly encountered isolates in BK. Dose frequency for 0.3% ofloxacin should be in line with the manufacturers' maximum suggested drop regimen. Commonly suggested drop regimens below these recommendations for either FQ may need to be revised in view of these findings.

Drug Delivery for Ocular Allergy: Current Formulation Design Strategies and Future Perspectives

The incidences of ocular allergy have been growing with the increase in pollution. Because of challenges in new drug development, there have been efforts to maximize the efficacy of existing drugs through drug delivery approaches. The effectiveness of drugs in ophthalmic conditions is primarily determined by permeability across the barrier, corneal retention, and sustained release. Thus, there have been widespread efforts to optimize these parameters to enhance efficacy through novel formulations. This review aims to analyze the approaches to drug delivery systems to encourage further research to optimize effectiveness. With this objective, research on drug delivery aspects of anti-allergy therapeutics was included and analyzed based on formulation/drug delivery technique, Food and Drug Administration approval limits, residence time, compatibility, pre-clinical efficacy, and potential for translational application. Conventional eye drops have concerns such as poor residence time and ocular bioavailability. The novel formulations have the potential to improve residence and bioavailability. However, the use of preservatives and the lack of regulatory approval for polymers limit the translational application. The review may assist readers in identifying novel drug delivery strategies and their limitations for the development of effective ophthalmic formulations for the treatment of ocular allergy.

Microneedle-based ocular drug delivery systems - recent advances and challenges

Eye diseases and injuries constitute a significant clinical problem worldwide. Safe and effective delivery of drugs to the eye is challenging mostly due to the presence of ocular barriers and clearance mechanisms. In everyday practice, the traditional eye drops, gels and ointments are most often used. Unfortunately, they are usually not well tolerated by patients due to the need for frequent use as well as the discomfort during application. Therefore, novel drug delivery systems with improved biopharmaceutical properties are a subject of ongoing scientific investigations. Due to the developments in microtechnology, in recent years, there has been a remarkable advance in the development of microneedle-based systems as an alternative, non-invasive form for administering drugs to the eye. This review summarizes the latest achievements in the field of obtaining microneedle ocular patches. In the manuscript, the most important manufacturing technologies, microneedle classification, and the research studies related to ophthalmic application of microneedles are presented. Finally, the most important advantages and drawbacks, as well as potential challenges related to the unique anatomy and physiology of the eye are summarized and discussed.

Recent advancements in polymeric nanofibers for ophthalmic drug delivery and ophthalmic tissue engineering

Nanofibers due to their unique properties such as high surface-to-volume ratio, porous structure, mechanical strength, flexibility and their resemblance to the extracellular matrix, have been researched extensively in the field of ocular drug delivery and tissue engineering. Further, different modifications considering the formulation and process parameters have been carried out to alter the drug release profile and its interaction with the surrounding biological environment. Electrospinning is the most commonly used technique for preparing nanofibers with industrial scalability. Advanced techniques such as co-axial electrospinning and combined system such as embedding nanoparticles in nanofiber provide an alternative approach to enhance the performance of the scaffold. Electrospun nanofibers offers a matrix like structure for cell regeneration. Nanofibers have been used for ocular delivery of various drugs like antibiotics, anti-inflammatory and various proteins. In addition, lens-coated medical devices provide new insights into the clinical use of nanofibers. Through fabricating the nanofibers researchers have overcome the issues of low bioavailability and compatibility with ocular tissue. Therefore, nanofibers have great potential in ocular drug delivery and tissue engineering and have the capacity to revolutionize these therapeutic areas in the field of ophthalmology. This review is mainly focused on the recent advances in the preparation of nanofibers and their applications in ocular drug delivery and tissue engineering. The authors have attempted to emphasize the processing challenges and future perspectives along with an overview of the safety and toxicity aspects of nanofibers.

Alginate as a Promising Biopolymer in Drug Delivery and Wound Healing: A Review of the State-of-the-Art

Biopolymeric nanoparticulate systems hold favorable carrier properties for active delivery. The enhancement in the research interest in alginate formulations in biomedical and pharmaceutical research, owing to its biodegradable, biocompatible, and bioadhesive characteristics, reiterates its future use as an efficient drug delivery matrix. Alginates, obtained from natural sources, are the colloidal polysaccharide group, which are water-soluble, non-toxic, and non-irritant. These are linear copolymeric blocks of α-(1→4)-linked l-guluronic acid (G) and β-(1→4)-linked d-mannuronic acid (M) residues. Owing to the monosaccharide sequencing and the enzymatically governed reactions, alginates are well-known as an essential bio-polymer group for multifarious biomedical implementations. Additionally, alginate’s bio-adhesive property makes it significant in the pharmaceutical industry. Alginate has shown immense potential in wound healing and drug delivery applications to date because its gel-forming ability maintains the structural resemblance to the extracellular matrices in tissues and can be altered to perform numerous crucial functions. The initial section of this review will deliver a perception of the extraction source and alginate’s remarkable properties. Furthermore, we have aspired to discuss the current literature on alginate utilization as a biopolymeric carrier for drug delivery through numerous administration routes. Finally, the latest investigations on alginate composite utilization in wound healing are addressed.

Formulation and Evaluation of Moxifloxacin Loaded Bilosomes In-Situ Gel: Optimization to Antibacterial Evaluation

In this study, moxifloxacin (MX)-loaded bilosome (BS) in situ gel was prepared to improve ocular residence time. MX-BSs were prepared using the thin-film hydration method. They were optimized using a Box−Behnken design (BBD) with bile salt (A, sodium deoxycholate), an edge activator (B, Cremophor EL), and a surfactant (C, Span 60) as process variables. Their effects were assessed based on hydrodynamic diameter (Y1), entrapment efficacy (Y2), and polydispersity index (Y3). The optimized formulation (MX-BSop) depicted a low hydrodynamic diameter (192 ± 4 nm) and high entrapment efficiency (76 ± 1%). Further, MX-BSop was successfully transformed into an in situ gel using chitosan and sodium alginate as carriers. The optimized MX-BSop in situ gel (MX-BSop-Ig4) was further evaluated for gelling capacity, clarity, pH, viscosity, in vitro release, bio-adhesiveness, ex vivo permeation, toxicity, and antimicrobial properties. MX-BSop-Ig4 exhibited an optimum viscosity of 65.4 ± 5.3 cps in sol and 287.5 ± 10.5 cps in gel states. The sustained release profile (82 ± 4% in 24 h) was achieved with a Korsmeyer−Peppas kinetic release model (R2 = 0.9466). Significant bio-adhesion (967.9 dyne/cm2) was achieved in tear film. It also exhibited 1.2-fold and 2.8-fold higher permeation than MX-Ig and a pure MX solution, respectively. It did not show any toxicity to the tested tissue, confirmed by corneal hydration (77.3%), cornea histopathology (no internal changes), and a HET-CAM test (zero score). MX-BSop-Ig4 exhibited a significantly (p < 0.05) higher antimicrobial effect than pure MX against Staphylococcus aureus and Escherichia coli. The findings suggest that bilosome in situ gel is a good alternative to increase corneal residence time, as well as to improve therapeutic activity.

Novel Drug Delivery Systems to Improve the Treatment of Keratitis

Keratitis is a disease characterized by inflammation of the cornea caused by different pathogens. It can cause serious visual morbidity if not treated quickly. Depending on the pathogen causing keratitis, eye drops containing antibacterial, antifungal, or antiviral agents such as besiloxacin, moxifloxacin, ofloxacin, voriconazol, econazole, fluconazole, and acyclovir are used, and these drops need to be applied frequently due to their low bioavailability. Studies are carried out on formulations with extended residence time in the cornea and increased permeability. These formulations include various new drug delivery systems such as inserts, nanoparticles, liposomes, niosomes, cubosomes, microemulsions, in situ gels, contact lenses, nanostructured lipid carriers, carbon quantum dots, and microneedles. Ex vivo and in vivo studies with these formulations have shown that the residence time of the active substances in the cornea is prolonged, and their ocular bioavailability is increased. In addition, in vivo studies have shown that these formulations successfully treat keratitis. However, it has been observed that fluoroquinolones are used in most of the studies; similar drug delivery systems are generally preferred for antifungal drugs, and studies for viral and acanthameba keratitis are limited. There is a need for new studies on different types of keratitis and different drug active substances. At the same time, proving the efficacy of drug delivery systems, which give promising results in in vivo animal models, with clinical studies is of great importance for progress in the treatment of keratitis.

Design of Besifloxacin HCl-Loaded Nanostructured Lipid Carriers: In Vitro and Ex Vivo Evaluation

Objective: In the treatment of severe cases of bacterial keratitis, conventional eye drops containing antibiotics should be applied daily and very frequently. The aim of this study is to develop low-dose high-effect formulations with the prepared nanostructured lipid carrier (NLC) formulations to reduce antibiotic resistance and increase patient compliance. Methods: NLC formulations were loaded with besifloxacin HCl (BHL) and the besifloxacin HCl: sulfobutyl ether beta-cyclodextrin (SBE-CD) complex. Positive charge was gained with chitosan, and corneal permeation and resolubility were increased with SBE-CD. In vitro characterization studies, permeability studies, and cytotoxicity and ex vivo transport studies were carried out. Results: In this study, it was found that SBE-CD increased BHL's solubility by 8-fold based on phase solubility studies. The optimized NLCs were small in size (13.63-16.09 nm) with a low polydispersity index (0.107-0.181) and adequate BHL drug loading efficiency. In vitro release studies showed that formulations were released approximately for 8 h and at levels over the minimum inhibitory concentration of Pseudomonas aeruginosa and Staphylococcus aureus. NLC formulations had a better corneal permeation rate than the marketed product during 6 h of ex vivo studies. Conclusions: According to in vitro and ex vivo data, it was determined that the most favorable NLC formulation was the formulation containing BHL/SBE-CD that was covered with chitosan. It has the highest drug loading capacity and one of the highest ex vivo corneal passage levels, along with desired drug release. The formulation containing BHL/SBE-CD and chitosan can be a potential alternative for the treatment of bacterial keratitis.

Improved solubility and corneal permeation of PEGylated curcumin complex used for the treatment of ophthalmic bacterial infections

Naturally occurring curcumin can be used for the treatment of corneal bacterial infections with its limitation of poor solubility. Aim of the present study was to enhance solubility and permeation of curcumin for the treatment of corneal bacterial infections. For increasing solubility, curcumin and polyethylene glycol (PEG 6000) complex (1:3) was prepared by fusion melting method. Phase solubility studies were used for the calculation of Gibbs free energy of curcumin. Central composite rotatable design (CCRD) was applied for optimization of Curcumin (CUR), PEGylated Curcumin (PEG-CUR), penetration enhancer cremophore (CR). Optimized ointments were further evaluated by mucous permeation, membrane permeability and cell toxicity studies by Transwell cell, ussing chamber and Caco-2 cells respectively. Antibacterial test was also performed by agar well diffusion method. Solubility of PEG-CUR was increased up to 93±3.2% as compared to pure curcumin and content uniformity was in the range of 95-110%. Curcumin permeation from PEG-CUR ointment was increased up to 12 folds. No toxicity of Caco-2 cells for PEG-CUR even after 24h was observed. Activity index of pure CUR, PEG-CUR ointment with or without CR against S. aureus and P. aeruginosa was 97±2.3, 96±1.6, 95±2.5% respectively. Ointment with solubility enhanced PEG-CUR and cremophore can be used as a promising tool for the treatment of corneal bacterial infections.

Bibliometric and visualized analysis of ocular drug delivery from 2001 to 2020

OBJECTIVE

To perform a bibliometric analysis in the field of ocular drug delivery research to characterize the current international trends and to present visual representations of the past and emerging trends on ocular drug delivery research over the past decade.

METHOD

In this cross-sectional study, a bibliometric analysis of data retrieved and extracted from the Web of Science Core Collection (WoSCC) database was performed to analyze evolution and theme trends on ocular drug delivery research from January 1, 2001, to December 31, 2020. A total of 4334 articles on ocular drug delivery were evaluated for specific characteristics, such as publication year, journals, authors, institutions, countries/regions, references, and keywords. Co-authorship analysis, co-occurrence analysis, co-citation analysis, and network visualization were constructed by VOSviewer. Some important subtopics identified by bibliometric characterization were further discussed and reviewed.

RESULTS

From 2001 to 2020, the annual global publications increased by 746.15%, from 52 to 440. International Journal of Pharmaceutics published the most manuscripts (250 publications) and produced the highest citations (9509 citations), followed by Investigative Ophthalmology & Visual Science (202 publications) and Journal of Ocular Pharmacology and Therapeutics (136 publications). The United States (1289 publications, 31,512 citations), the University of Florida (82 publications, 2986 citations), and Chauhan, Anuj (52 publications, 2354 citations) were the most productive and impactful institution, country, and author respectively. The co-occurrence cluster analysis of the top 100 keywords form five clusters: (1) micro/nano ocular drug delivery systems; (2) the treatment of inflammation and posterior diseases; (3) macroscopic ocular drug delivery systems/devices; (4) the characteristics of drug delivery systems; (5) and the ocular drug delivery for glaucoma treatment. Diabetic macular edema, anti-VEGF, ranibizumab, bevacizumab, micelles and latanoprost, were the latest high-frequency keywords, indicating the emerging frontiers of ocular drug delivery. Further discussions into the subtopics were provided to assist researchers to determine the range of research topics and plan research direction.

CONCLUSIONS

Over the last two decades there has been a progressive increase in the number of publications and citations on research related to ocular drug delivery across many countries, institutions, and authors. The present study sheds light on current trends, global collaboration patterns, basic knowledge, research hotspots, and emerging frontiers of ocular drug delivery. Novel solutions for ocular drug delivery and the treatment of inflammation and posterior diseases were the major themes over the last 20 years.

Optimization of the Micellar-Based In Situ Gelling Systems Posaconazole with Quality by Design (QbD) Approach and Characterization by In Vitro Studies

Background: Fungal ocular infections can cause serious consequences, despite their low incidence. It has been reported that Posaconazole (PSC) is used in the treatment of fungal infections in different ocular tissues by diluting the oral suspension, and successful results were obtained despite low ocular permeation. Therefore, we optimized PSC-loaded ocular micelles and demonstrated that the permeation/penetration of PSC in ocular tissues was enhanced. Methods: The micellar-based in situ gels based on the QbD approach to increase the ocular bioavailability of PSC were developed. Different ratios of Poloxamer 407 and Poloxamer 188 were chosen as CMAs. Tsol/gel, gelling capacity and rheological behavior were chosen as CQA parameters. The data were evaluated by Minitab 18, and the formulations were optimized with the QbD approach. The in vitro release study, ocular toxicity, and anti-fungal activity of the optimized formulation were performed. Results: Optimized in situ gel shows viscoelastic property and becomes gel form at physiological temperatures even when diluted with the tear film. In addition, it has been shown that the formulation had high anti-fungal activity and did not have any ocular toxicity. Conclusions: In our previous studies, PSC-loaded ocular micelles were developed and optimized for the first time in the literature. With this study, the in situ gels of PSC for ocular application were developed and optimized for the first time. The optimized micellar-based in situ gel is a promising drug delivery system that may increase the ocular permeation and bioavailability of PSC.

Considerations for Polymers Used in Ocular Drug Delivery

PURPOSE

Age-related eye diseases are becoming more prevalent. A notable increase has been seen in the most common causes including glaucoma, age-related macular degeneration (AMD), and cataract. Current clinical treatments vary from tissue replacement with polymers to topical eye drops and intravitreal injections. Research and development efforts have increased using polymers for sustained release to the eye to overcome treatment challenges, showing promise in improving drug release and delivery, patient experience, and treatment compliance. Polymers provide unique properties that allow for specific engineered devices to provide improved treatment options. Recent work has shown the utilization of synthetic and biopolymer derived biomaterials in various forms, with this review containing a focus on polymers Food and Drug Administration (FDA) approved for ocular use.

METHODS

This provides an overview of some prevalent synthetic polymers and biopolymers used in ocular delivery and their benefits, brief discussion of the various types and synthesis methods used, and administration techniques. Polymers approved by the FDA for different applications in the eye are listed and compared to new polymers being explored in the literature. This article summarizes research findings using polymers for ocular drug delivery from various stages: laboratory, preclinical studies, clinical trials, and currently approved. This review also focuses on some of the challenges to bringing these new innovations to the clinic, including limited selection of approved polymers.

RESULTS

Polymers help improve drug delivery by increasing solubility, controlling pharmacokinetics, and extending release. Several polymer classes including synthetic, biopolymer, and combinations were discussed along with the benefits and challenges of each class. The ways both polymer synthesis and processing techniques can influence drug release in the eye were discussed.

CONCLUSION

The use of biomaterials, specifically polymers, is a well-studied field for drug delivery, and polymers have been used as implants in the eye for over 75 years. Promising new ocular drug delivery systems are emerging using polymers an innovative option for treating ocular diseases because of their tunable properties. This review touches on important considerations and challenges of using polymers for sustained ocular drug delivery with the goal translating research to the clinic.

Challenges and solutions in polymer drug delivery for bacterial biofilm treatment: A tissue-by-tissue account

To tackle the emerging antibiotic resistance crisis, novel antimicrobial approaches are urgently needed. Bacterial communities (biofilms) are a particular concern in this context. Biofilms are responsible for most human infections and are inherently less susceptible to antibiotic treatments. Biofilms have been linked with several challenging chronic diseases, including implant-associated osteomyelitis and chronic wounds. The specific local environments present in the infected tissues further contribute to the rise in antibiotic resistance by limiting the efficacy of systemic antibiotic therapies and reducing drug concentrations at the infection site, which can lead to reoccurring infections. To overcome the shortcomings of systemic drug delivery, encapsulation within polymeric carriers has been shown to enhance antimicrobial efficacy, permeation and retention at the infection site. In this Review, we present an overview of current strategies for antimicrobial encapsulation within polymeric carriers, comparing challenges and solutions on a tissue-by-tissue basis. We compare challenges and proposed drug delivery solutions from the perspective of the local environments for biofilms found in oral, wound, gastric, urinary tract, bone, pulmonary, vaginal, ocular and middle/inner ear tissues. We will also discuss future challenges and barriers to clinical translation for these therapeutics. The following Review demonstrates there is a significant imbalance between the research focus being placed on different tissue types, with some targets (oral and wound biofims) being extensively more studied than others (vaginal and otitis media biofilms and endocarditis). Furthermore, the importance of the local tissue environment when selecting target therapies is demonstrated, with some materials being optimal choices for certain sites of bacterial infection, while having limited applicability in others.

Development of Oral Tablet Formulation Containing Erlotinib: Randomly Methylated-β-cyclodextrin Inclusion Complex Using Direct Compression Method

Objectives

Erlotinib (ERL) is a tyrosine kinase inhibitor that has been used in the treatment of metastatic non-small cell lung cancer (NSCLC). However, its low aqueous solubility limits its absorption and oral bioavailability. To overcome these pharmacokinetic drawbacks, complexation of ERL can be applied. The aim of this study was to develop and characterize an oral tablet formulation containing ERL: Randomly methylated-β-cyclodextrin (RAMEB-CD) inclusion complex to enhance solubility and oral bioavailability of ERL.

Materials and Methods

An inclusion complex was prepared with RAMEB-CD using co-lyophilization technique. Structural characterization was performed using X-ray diffractometry and fourier-transform infrared spectroscopy. Tablet formulation of ERL: RAMEB-CD inclusion complex were prepared using direct compression technique. Tablet characteristics like hardness, diameter, thickness, friability, weight variability, disintegration and dissolution were evaluated. Flow properties of the powder were also determined.

Results

Characterization studies suggested that stable complexes between ERL and RAMEB-CD were obtained with co-lyophilization method. Tablet formulation using inclusion complex of ERL and RAMEB-CD with drug dose equivalent to 25 mg was successfully prepared using direct compression technique. Physical properties of the powder mixture were studied - angle of repose (°): 34.27±1.78; flow time: 2.2±0.4; HR: 1.05±0.02; compressibility index: 14.27±1.55. Moisture content (%) was found to be 0.27±0.05. The thickness, diameter and hardness values were 3.92±0.05 mm, 11.3±0.06 mm and 81.38±2.27 N, respectively. In uniformity of weight test, the average weight was 404.57±1.6 mg, with less than 5% deviation in 20 randomly selected tablets. Friability value was 0.27% and the disintegration time was found to be less than 15 min. Importantly, dissolution study showed that solubility of ERL was increased by complexation with RAMEB-CD. After 60 minutes, 99% of drug was released from the tablet formulation.

Conclusion

These results demonstrate that a new tablet formulation of ERL: RAMEB-CD inclusion complex could be an alternative approach to achieve increased dissolution and oral bioavailability of ERL for NSCLC treatment.

A Systematic Review of Drug-Loaded Electrospun Nanofiber-Based Ophthalmic Inserts

Currently, ocular inserts and nanoparticles have received much attention due to the limited bioavailability of conventional eye preparations and the toxicity problems of systemic drug administration. The current systematic review aims to present recent studies on the use of electrospun nanofiber-based ocular inserts to improve the bioavailability of drugs used for different ophthalmic diseases. A systematic search was performed in PubMed, Ovid Medline, Web of Science, ScienceDirect, Scopus, Reaxys, Google Scholar, and Google Patents/Espacenet taking "drug-loaded", "nanofibers", and "ophthalmic inserts" and their equivalent terms as keywords. The search was limited to original and peer-reviewed studies published in 2011-2021 in English language. Only 13 out of 795 articles and 15 out of 197 patents were included. All results revealed the success of nanofiber-based ocular inserts in targeting and improved bioavailability. Ocular inserts based on nanofibers can be used as safe, efficient carriers for the treatment of anterior and posterior eye diseases.

Structural Characterization of the Millennial Antibacterial (Fluoro)Quinolones-Shaping the Fifth Generation

The evolution of the class of antibacterial quinolones includes the introduction in therapy of highly successful compounds. Although many representatives were withdrawn due to severe adverse reactions, a few representatives have proven their therapeutical value over time. The classification of antibacterial quinolones into generations is a valuable tool for physicians, pharmacists, and researchers. In addition, the transition from one generation to another has brought new representatives with improved properties. In the last two decades, several representatives of antibacterial quinolones received approval for therapy. This review sets out to chronologically outline the group of approved antibacterial quinolones since 2000. Special attention is given to eight representatives: besifloxacin, delafoxacin, finafloxacin, lascufloxacin, nadifloxacin and levonadifloxacin, nemonoxacin, and zabofloxacin. These compounds have been characterized regarding physicochemical properties, formulations, antibacterial activity spectrum and advantageous structural characteristics related to antibacterial efficiency. At present these new compounds (with the exception of nadifloxacin) are reported differently, most often in the fourth generation and less frequently in a new generation (the fifth). Although these new compounds' mechanism does not contain essential new elements, the question of shaping a new generation (the fifth) arises, based on higher potency and broad spectrum of activity, including resistant bacterial strains. The functional groups that ensured the biological activity, good pharmacokinetic properties and a safety profile were highlighted. In addition, these new representatives have a low risk of determining bacterial resistance. Several positive aspects are added to the fourth fluoroquinolones generation, characteristics that can be the basis of the fifth generation. Antibacterial quinolones class continues to acquire new compounds with antibacterial potential, among other effects. Numerous derivatives, hybrids or conjugates are currently in various stages of research.

Recent applications of electrical, centrifugal, and pressurised emerging technologies for fibrous structure engineering in drug delivery, regenerative medicine and theranostics

Advancements in technology and material development in recent years has led to significant breakthroughs in the remit of fiber engineering. Conventional methods such as wet spinning, melt spinning, phase separation and template synthesis have been reported to develop fibrous structures for an array of applications. However, these methods have limitations with respect to processing conditions (e.g. high processing temperatures, shear stresses) and production (e.g. non-continuous fibers). The materials that can be processed using these methods are also limited, deterring their use in practical applications. Producing fibrous structures on a nanometer scale, in sync with the advancements in nanotechnology is another challenge met by these conventional methods. In this review we aim to present a brief overview of conventional methods of fiber fabrication and focus on the emerging fiber engineering techniques namely electrospinning, centrifugal spinning and pressurised gyration. This review will discuss the fundamental principles and factors governing each fabrication method and converge on the applications of the resulting spun fibers; specifically, in the drug delivery remit and in regenerative medicine.

Age-related ocular conditions: Current treatments and role of cyclodextrin-based nanotherapies

Age-related eye disorders are chronic diseases that affect millions of people worldwide. They cause visual impairment and, in some cases, irreversible blindness. Drug targeting to the retina is still a challenge due to the difficulties with drug distribution, crossing eye barriers, and reaching intraocular tissues in an effective therapeutic concentration. Although intravitreal injections can directly deliver drugs to the posterior segment of the eye, it remains an invasive technique and leads to several side effects. Conventional formulations such as emulsions, suspensions, or ointments have been related to frequent instillation and inability to reach intraocular tissues. New drug delivery systems and medical devices have also been designed. Nevertheless, these treatments are not always effective and sometimes require the presence of a specialist for the administration of the dose. Therefore, treatments for age-related ocular diseases remain as one of the major unmet clinical needs to manage these widespread eye conditions. Nanotechnology may become the adequate tool for developing effective and non-invasive therapies suitable for self-administration. In this review, we discuss emerging therapeutic options based on nanoengineering of cyclodextrin nanocarriers for the treatment of age-related eye disorders, including their pathophysiology, pharmacological options, and feasibility of clinical translation.

Development and optimization of hot-melt extruded moxifloxacin hydrochloride inserts, for ocular applications, using the design of experiments

The current study sought to formulate sustained-release hot-melt extruded (HME) ocular inserts of moxifloxacin hydrochloride (MOX; MOX-HME) for the treatment of bacterial keratitis. The concentration of Eudragit™ FS-100 (FS) and propylene glycol (PG) used as polymer and plasticizer, respectively, in the inserts were optimized using the central composite design (CCD) to achieve sustained release. The inserts were characterized for weight, thickness, surface characteristics, pH, and in vitro release profile. The crystalline characteristics of MOX and surface morphology of the inserts were evaluated using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Furthermore, ex vivo permeation through rabbit cornea and stability of the optimized MOX-HME insert was investigated. The results demonstrate an inverse correlation between FS concentration and MOX release from the MOX-HME inserts, and a potential 24 h release. The optimized MOX-HME inserts were found to be stable at room temperature for four months, showing no significant change in drug content, pH and release profile. MOX converted into an amorphous form in the MOX-HME inserts and did not recrystallize during the study period. SEM analysis confirmed the smooth surface of the MOX-HME insert. The ex vivo studies revealed that the MOX-HME inserts provided a much prolonged transcorneal MOX flux as compared to the commercial ophthalmic solution and the immediate-release MOX-HME insert. The results indicate that MOX-HME inserts could potentially provide a once-a-day application, consequently reducing the dosing frequency and acting as an alternative delivery system in the management of bacterial infections.

Thiolation of Biopolymers for Developing Drug Delivery Systems with Enhanced Mechanical and Mucoadhesive Properties: A Review

Biopolymers are extensively used for developing drug delivery systems as they are easily available, economical, readily modified, nontoxic, biodegradable and biocompatible. Thiolation is a well reported approach for enhancing mucoadhesive and mechanical properties of polymers. In the present review article, for the modification of biopolymers different thiolation methods and evaluation/characterization techniques have been discussed in detail. Reported literature on thiolated biopolymers with enhanced mechanical and mucoadhesive properties has been presented conspicuously in text as well as in tabular form. Patents filed by researchers on thiolated polymers have also been presented. In conclusion, thiolation is an easily reproducible and efficient method for customization of mucoadhesive and mechanical properties of biopolymers for drug delivery applications.