Formulation of olopatadine hydrochloride viscous eye drops - physicochemical, biopharmaceutical and efficacy assessment using in vitro and in vivo approaches

Innovative Famciclovir Eye Drop Formulations for Herpes Zoster Infections

PURPOSE

Herpes zoster ophthalmicus, a manifestation of the varicella-zoster virus in the eye, presents significant clinical challenges. As there is no direct ocular treatment for this infection, new therapeutic options should be studied. Famciclovir, a widely used antiviral drug for herpes zoster, offers higher bioavailability than acyclovir (a common herpes zoster treatment). However, this drug is currently limited to oral dosage forms, which are associated with inherent limitations such as variable absorption or gastrointestinal side effects. This study aimed to formulate new famciclovir eye drops for controlled drug release and targeted delivery to the cornea and sclera.

METHOD

Eye drop formulations containing various polymers (polyvinyl alcohol, hydroxypropyl methyl cellulose and chitosan) were developed and evaluated for physicochemical properties, irritation index and stability. The best performing formulation was used in ex-vivo diffusion and retention studies with rabbit cornea and sclera. The results were analyzed with a new HPLC validation method.

RESULTS

The formulation with polyvinyl alcohol exhibited superior properties regarding transparency, turbidity and absence of bubbles. It maintained a physiological pH over time and had an appropriate viscosity of 19.97 ± 0.25 mPa.s. Non-irritancy was confirmed by the HET-CAM test, and the formulation was stable at room temperature (25 °C), fridge (4 °C) and freezer (-80 °C). Ex- vivo diffusion studies revealed higher diffusion through the sclera compared to the cornea, with greater drug accumulation in sclera.

CONCLUSIONS

These findings suggest that famciclovir eye drops may offer a viable treatment for ocular herpes zoster infections. Famciclovir also diffuses and retains in targeted membranes, possibly enhancing its therapeutic effects.

Stability and Efficacy of Mucoadhesive Eye Drops Containing Olopatadine HCl: Physicochemical, Functional, and Preclinical In Vivo Assessment

Background: The incorporation of polymers into drug delivery vehicles has been shown to be an effective strategy to prolong the residence time of active ingredients in the precorneal tear film and to increase ocular bioavailability. Objectives: The aim of this study was to develop novel, viscous eye drops containing olopatadine (OCH) as the active ingredient, polysaccharides hydroxypropyl guar gum (HPG), and sodium hyaluronate (SH), individually, and in combination as functional polymers. Methods: Viscous eye drops containing 0.1% OCH in combination with HPG (0.25%) and SH (0.4%), were prepared and evaluated for their physicochemical properties, rheological behavior, mucoadhesion, and preliminary stability. A novel rheological method was used to evaluate the resistance of the eye drops under simulated blinking conditions. In vivo efficacy was evaluated using an ocular itch test in mice to compare the formulations with a commercial product. Results: The formulations remained stable and transparent, with physicochemical parameters within acceptable ranges. Rheological studies confirmed pseudoplastic flow, with the HPG-SH combination exhibiting enhanced viscosity and shear-thinning properties for prolonged retention in the eye. Mucoadhesion was highest in SH-HPG formulations. During simulated blinking cycles, eye drops containing a combination of SH and HPG polymers fully regained their initial viscosity during the resting periods. Preliminary stability studies indicate that the formulated eye drops exhibit satisfactory physicochemical stability under various storage conditions. In vivo, OCH-SH and OCH-HPG-SH drops provided prolonged antipruritic and analgesic effects compared to the reference product. Conclusions: Polysaccharide-based innovative formulations improve OCH retention, enhancing therapeutic efficacy and patient compliance in the treatment of allergic conjunctivitis.

From Preformulative Design to In Vivo Tests: A Complex Path of Requisites and Studies for Nanoparticle Ocular Application. Part 1: Design, Characterization, and Preliminary In Vitro Studies

Ocular pathologies are widely diffused worldwide, and their effective treatment, combined with a high patient compliance, is sometimes challenging to achieve due to the barriers of the eye; in this context, the use of nanoparticles for topical ophthalmic application could represent a successful strategy. Aiming to develop nanoplatforms with potential clinical applications, great attention has to be paid to their features, in relation to the route of administration and to the pharmacopoeial requirements. This review (part 1) thus embraces the preliminary steps of nanoparticle development and characterization. At the beginning, the main barriers of the eye and the different administration routes are resumed, followed by a general description of the advantages of the employment of nanoparticles for ocular topical administration. Subsequently, the preformulative steps are discussed, deepening the choice of raw materials and determining the quantitative composition. Then, a detailed report of the physicochemical and technological characterization of nanoparticles is presented, analyzing the most relevant tests that should be performed on nanoparticles to verify their properties and the requisites (both mandatory and suggested) demanded by regulatory agencies. In conclusion, some preliminary noncellular in vitro evaluation methods are described. Studies from in vitro cellular assays to in vivo tests will be discussed in a separate (part 2) review paper. Hence, this overview aims to offer a comprehensive tool to guide researchers in the choice of the most relevant studies to develop a nanoplatform for ophthalmic drug administration.

Development of Gentamicin Bilosomes Laden In Situ Gel for Topical Ocular Delivery: Optimization, In Vitro Characterization, Toxicity, and Anti-microbial Evaluation

Purpose

The eye drops are the prominent preparation used to treat surface eye disease (bacterial conjunctivitis). However, they have some limitations i.e., short corneal residence, resulting in low ocular bioavailability and necessitating frequent dose administration. The present study developed gentamicin (GE) bilosomes (BM)- laden in situ gel to improve therapeutic activity. The in situ gel system is initially in sol form before administration and converted into gel form in physiological eye conditions.

Methods

The GE-BM was developed using the thin film hydration technique and optimized by D-optimal design. GE-BM was characterized for vesicle size, entrapment efficiency, zeta potential, morphology, and Fourier transform electron microscope (FTIR). The optimized GE-BM (GE-BMopt) was incorporated into an in situ gel and assessed for physicochemical characteristics. GE-BMopt in situ gel was evaluated for in vitro release, ex vivo permeation, toxicity, and antimicrobial study.

Results

GE-BMopt has a vesicle size of 185.1±4.8nm, PDI of 0.254, zeta potential of 27.6 mV, entrapment efficiency of 81.86±1.29 %, and spherical morphology. The FTIR study presented no chemical interactions between GE and excipients. GE-BMopt in situ gel (GE-BMoptIG4) showed excellent viscosity, gelling strength, and ex-vivo bio-adhesion. GE-BMopt-IG4 showed significant high and sustained release of GE (78.08±4.73% in 12h). GE-BMopt-IG4 displayed 3.27-fold higher ex-vivo goat corneal permeation than a pure GE solution. GE-BMopt-IG4 showed good corneal tolerance without any damage or irritation. GE-BMopt-IG4 showed significantly (P<0.05) higher anti-bacterial activity (ZOI) against Staphylococcus aureus and Escherichia coli than pure GE solution.

Conclusion

The study determined that the BM in situ gel system can serve as a substitute carrier for GE to enhance its therapeutic effectiveness, and further preclinical studies are required.

A review on revolutionizing ophthalmic therapy: Unveiling the potential of chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer in eye disease treatments

Ocular disorders, encompassing both common ailments like dry eye syndrome and more severe situations for instance age-related macular degeneration, present significant challenges to effective treatment due to the intricate architecture and physiological barriers of the eye. Polysaccharides are emerging as potential solutions for drug delivery to the eyes due to their compatibility with living organisms, natural biodegradability, and adhesive properties. In this review, we explore not only the recent advancements in polysaccharide-based technologies and their transformative potential in treating ocular illnesses, offering renewed optimism for both patients and professionals but also anatomy of the eye and the significant obstacles hindering drug transportation, followed by an investigation into various drug administration methods and their ability to overcome ocular-specific challenges. Our focus lies on biological adhesive polymers, including chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer, known for their adhesive characteristics enhancing drug retention on ocular surfaces and increasing bioavailability. A detailed analysis of material designs used in ophthalmic formulations, such as gels, lenses, eye drops, nanofibers, microneedles, microspheres, and nanoparticles, their advantages and limitations, the potential of formulations in improving therapeutic outcomes for various eye conditions. Moreover, we underscore the discovery of novel polysaccharides and their potential uses in ocular drug delivery.

Synergism of polysaccharide polymers in antihistamine eye drops: Influence on physicochemical properties and in vivo efficacy

The incorporation of polymers into drug delivery vehicles has been shown to be a useful approach to prolong the residence time of drugs in the precorneal tear film and to improve penetration into biological membranes. The main objective of this research was to formulate novel viscous eye drops with ketotifen as the active ingredient, containing the polysaccharides: chitosan (MCH), hydroxypropyl guar gum (HPG) and hyaluronic acid (SH) alone and in combination as functional polymers. DSC and FT-IR techniques showed the compatibility between ketotifen and polymers. Physicochemical and rheological analysis at ambient and simulated physiological conditions, as well as the evaluation of mucoadhesive properties showed that vehicles containing combinations of polymers have suitable physicochemical and functional properties with demonstrated synergism between combined polymers (MCH and HPG i.e. SH and HPG). The drug permeability was successfully estimated in vitro using HCE-T cell-based models. MTT cytotoxicity assay demonstrates that the tested formulations were non-toxic and well tolerated. In vivo preclinical study on mice revealed that both vehicles containing mixed polymers enhanced and prolonged the antipruritic/analgesic-like effect of ophthalmic ketotifen. Based on these results, both combinations of polysaccharide polymers, especially SH-HPG, could be considered as potential new carriers for ketotifen for ophthalmic use.

Ocular Delivery of Metformin for Sustained Release and in Vivo Efficacy

Metformin is known to lower inflammation, independent of its anti-diabetic action. Thus, topical metformin can be a therapeutic strategy for managing ocular inflammation associated with diabetes. To achieve this and address the issues of ocular retention and controlled release an in situ gel of metformin was developed. The formulations were prepared using sodium hyaluronate, hypromellose, and gellan gum. The composition was optimized by monitoring gelling time/capacity, viscosity, and mucoadhesion. MF5 was selected as the optimized formulation. It showed both chemical and physiological compatibility. It was found to be sterile and stable. MF5 exhibited sustained release of metformin for 8h that fitted best with zero-order kinetics. Further, the release mode was found to be close to the Korsmeyer-Peppas model. Supported by an ex vivo permeation study, it showed potential for prolonged action. It showed a significant reduction in ocular inflammation that was comparable to that of the standard drug. MF5 shows translational potential as a safe alternative to steroids for managing ocular inflammation.

Carbohydrate polymer-based bioadhesive formulations and their potentials for the treatment of ocular diseases: A review

Eyes are directly exposed to the outer environment and susceptible to infections, leading to various ocular disorders. Local medication is preferred to treat eye diseases due to its convenience and compliance. However, the rapid clearance of the local formulations highly limits the therapeutic efficacy. In the past decades, several carbohydrate bioadhesive polymers (CBPs), such as chitosan and hyaluronic acid, have been used in ophthalmology for sustained ocular drug delivery. These CBP-based delivery systems have improved the treatment of ocular diseases to a large extent but also caused some undesired effects. Herein, we aim to summarize the applications of some typical CBPs (including chitosan, hyaluronic acid, cellulose, cyclodextrin, alginate and pectin) in treating ocular diseases from the general view of ocular physiology, pathophysiology and drug delivery, and to provide a comprehensive understanding of the design of the CBP-based formulations for ocular use. The patents and clinical trials of CBPs for ocular management are also discussed. In addition, a discussion on the concerns of CBPs in clinical use and the possible solutions is presented.

Biopolymers in Mucoadhesive Eye Drops for Treatment of Dry Eye and Allergic Conditions: Application and Perspectives

Dry eye syndrome and allergic conjunctivitis are the most common inflammatory disorders of the eye surface. Although eye drops are the most usual prescribed dosage form, they are characterized by low ocular availability due to numerous barrier mechanisms of the eye. The use of biopolymers in liquid ophthalmic preparations has numerous advantages, such as increasing the viscosity of the tear film, exhibiting bioadhesive properties, and resisting the drainage system, leading to prolonged retention of the preparation at the site of application, and improvement of the therapeutic effect. Some mucoadhesive polymers are multifunctional excipients, so they act by different mechanisms on increasing the permeability of the cornea. Additionally, many hydrophilic biopolymers can also represent the active substances in artificial tear preparations, due to their lubrication and moisturizing effect. With the modification of conventional ophthalmic preparations, there is a need for development of new methods for their characterization. Numerous methods for the assessment of mucoadhesiveness have been suggested by the literature. This review gives an overview related to the development of mucoadhesive liquid ophthalmic formulations for the treatment of dry eye and allergic conditions.

Characterization and Evaluation of Rapamycin-Loaded Nano-Micelle Ophthalmic Solution

Rapamycin-loaded nano-micelle ophthalmic solution (RAPA-NM) offers a promising application for preventing corneal allograft rejection; however, RAPA-NM has not yet been fully characterized. This study aimed to evaluate the physicochemical properties, biocompatibility, and underlying mechanism of RAPA-NM in inhibiting corneal allograft rejection. An optimized RAPA-NM was successfully prepared using a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (PVCL-PVA-PEG) graft copolymer as the excipient at a PVCL-PVA-PEG/RAPA weight ratio of 18:1. This formulation exhibited high encapsulation efficiency (99.25 ± 0.55%), small micelle size (64.42 ± 1.18 nm), uniform size distribution (polydispersity index = 0.076 ± 0.016), and a zeta potential of 1.67 ± 0.93 mV. The storage stability test showed that RAPA-NM could be stored steadily for 12 weeks. RAPA-NM also displayed satisfactory cytocompatibility and high membrane permeability. Moreover, topical administration of RAPA-NM could effectively prevent corneal allograft rejection. Mechanistically, a transcriptomic analysis revealed that several immune- and inflammation-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were significantly enriched in the downregulated genes in the RAPA-NM-treated allografts compared with the rejected allogenic corneal grafts. Taken together, these findings highlight the potential of RAPA-NM in treating corneal allograft rejection and other ocular inflammatory diseases.

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.

Ophthalmic drugs: in vitro paraoxonase 1 inhibition and molecular docking studies

Glaucoma is a neuropathy disorder and is generally treated by drugs. Allergic conjunctivitis is a common ophthalmologic disease. Paraoxonase 1 (PON1) is an organophosphate hydrolyzer and antiatherogenic enzyme. PON1 is known for preventing atherosclerosis through lipid-modifying features, as well as which has decisive actions of antiapoptosis, anti-inflammatory, antithrombosis, and antiadhesion antioxidant activity properties. Thus, reducing the enzyme levels in hyperthyroidism, chronic renal failure, glaucoma, diabetes mellitus, and cardiovascular diseases is a significant risk. This study was tested some ophthalmic drugs used to treat the diseases, such as glaucoma and allergic conjunctivitis, mentioned above, travoprost, latanoprost, ketotifen, emedastine, and olopatadine, for their inhibition activities against PON1. These drugs displayed the potent inhibition effect with IC₅₀ values ranging between 14.95 ± 0.15 and 299.60 ± 4.07 μM and K_I constants ranging from 9.71 ± 2.63 to 261.50 ± 59.98 μM. Besides, the molecular docking analyses of the competitive inhibitors, travoprost, emedastine, and olopatadine, were performed to understand the binding interactions on the enzyme's binding site. According to both in vitro and in silico analysis results, travoprost had the most potent effect on PON1 enzyme activity.

mRNA-Based Nanomedicinal Products to Address Corneal Inflammation by Interleukin-10 Supplementation

The anti-inflammatory cytokine Interleukin-10 (IL-10) is considered an efficient treatment for corneal inflammation, in spite of its short half-life and poor eye bioavailability. In the present work, mRNA-based nanomedicinal products based on solid lipid nanoparticles (SLNs) were developed in order to produce IL-10 to treat corneal inflammation. mRNA encoding green fluorescent protein (GFP) or human IL-10 was complexed with different SLNs and ligands. After, physicochemical characterization, transfection efficacy, intracellular disposition, cellular uptake and IL-10 expression of the nanosystems were evaluated in vitro in human corneal epithelial (HCE-2) cells. Energy-dependent mechanisms favoured HCE-2 transfection, whereas protein production was influenced by energy-independent uptake mechanisms. Nanovectors with a mean particle size between 94 and 348 nm and a positive superficial charge were formulated as eye drops containing 1% (w/v) of polyvinyl alcohol (PVA) with 7.1-7.5 pH. After three days of topical administration to mice, all formulations produced GFP in the corneal epithelium of mice. SLNs allowed the obtaining of a higher transfection efficiency than naked mRNA. All formulations produce IL-10, and the interleukin was even observed in the deeper layers of the epithelium of mice depending on the formulation. This work shows the potential application of mRNA-SLN-based nanosystems to address corneal inflammation by gene augmentation therapy.