Development of a Luliconazole Nanoemulsion as a Prospective Ophthalmic Delivery System for the Treatment of Fungal Keratitis: In Vitro and In Vivo Evaluation

Design and Development of Dasatinib Nanoemulsions for Ocular Delivery: In vitro Characterization, Biocompatibility, and Ex vivo Ocular Irritation Study

Dasatinib, a potent tyrosine kinase inhibitor with dual anti-inflammatory and anti-angiogenic properties, holds significant potential for treating ocular diseases such as Corneal Neovascularization (CNV), uveitis, and diabetic retinopathy. However, its low aqueous solubility and limited ocular retention present major formulation challenges. This study concentrated on the design and evaluation of Dasatinib nanoemulsions (Dasa NEs) for ocular delivery, utilizing nanotechnology to enhance solubility, stability, and therapeutic efficacy. The Dasa NEs were prepared using Oleic acid (lipid phase), Tween 80, Propylene Glycol (PG) (Smix), with component ratios optimized through pseudo-ternary phase diagrams. The resulting formulations exhibited nanoscale droplet sizes (<100 nm), low polydispersity indices, and stable zeta potential, ensuring colloidal stability and efficient delivery. Comprehensive physicochemical evaluations confirmed that the NEs possessed ideal pH, refractive index, surface tension, and viscosity for ophthalmic applications. Biocompatibility assessments using the MTT assay on SIRC cells demonstrated high cell viability, while HET-CAM tests confirmed the absence of significant ocular irritation. In vitro diffusion studies indicated improved drug permeation, highlighting the potential for prolonged therapeutic effects. Stability studies further validated the robustness of the formulations under various conditions. The developed nanoemulsions offer a promising, non-invasive platform for ocular drug delivery, improving patient compliance and therapeutic outcomes. Future studies should focus on in vivo evaluations and long-term safety to advance the clinical translation of this novel formulation.

Overcoming barriers in formulating practically insoluble loteprednol etabonate in ophthalmic nanoemulsion

Loteprednol etabonate (LE) is a soft corticosteroid recently approved for the short-term treatment of signs and symptoms of dry eye disease. LE is available on the market as a suspension, which can release only limited amount of dissolved corticosteroid after application at the ocular surface. This study is focused on the development of an oil-in-water nanoemulsion (NE) to effectively deliver dissolved LE to the ocular surface, in order to promote its absorption. We newly developed an extended-throughput 3D model of the corneal epithelium for biocompatibility study, and an innovative approach to investigate the effect of biorelevant dilution on LE release from the NE oil phase. Castor oil, Capryol® 90, Kolliphor® EL and Soluplus® were selected as NE excipients based on their potential to dissolve LE. Design of experiments was successfully employed to develop biocompatible and physically stable NE with high LE content (0.15 %, w/w) and retention efficiency (87 % after 10 months of storage at room temperature). LE retention within oil droplets (above 90 % of the initial LE content) despite biorelevant dilution simulating tear turnover suggests the potential for direct LE absorption from the NE oil droplets into the lipophilic corneal epithelium. The results obtained encourage the extension of the studies in terms of in vitro permeability and in vivo eye-related bioavailability assessment to prove the potential of the proposed LE formulation.

Luliconazole-loaded nanostructured lipid carrier: formulation, characterization, and in vitro antifungal evaluation against a panel of resistant fungal strains

Luliconazole (LCZ) is a topical imidazole antifungal agent with broad-spectrum activity. However, LCZ encounters challenges such as low aqueous solubility, skin retention, and penetration, which reduce its dermal bioavailability and hinder its efficacy in drug delivery. The aim of the present study was to formulate, characterize, and evaluate the in vitro antifungal efficacy of luliconazole-loaded nanostructured lipid carriers (LCZ-NLCs) against a panel of resistant fungal strains. The LCZ-NLCs were synthesized using a modified emulsification-solvent evaporation technique. Characterization involved assessing parameters such as poly-dispersity index (PDI), zeta potential, encapsulation efficiency (EE %), Field Emission Scanning Electron Microscopy (FESEM), Differential Scanning Calorimetry (DSC) analysis, and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR). Furthermore, in vitro drug release experiments, analysis of release kinetics, cytotoxicity assessments, and in vitro antifungal susceptibility tests were performed as part of the study. The findings indicated that LCZ-NLCs displayed nanoscale dimensions, uniform dispersion, and a favorable zeta potential. The encapsulation efficiency of LCZ in NLCs was approximately 90%. FESEM analysis revealed spherical nanoparticles with consistent shape. ATR-FTIR analysis indicated no chemical interaction between LCZ and excipients. In vitro drug release experiments demonstrated that LCZ-NLCs notably improved the drug's dissolution rate. The stability testing confirmed consistent colloidal nanometer ranges in the LCZ-NLCs samples. Additionally, cytotoxicity tests revealed no toxicity within the tested concentration. Moreover, in vitro antifungal susceptibility tests demonstrated potent antifungal activity of LCZ-NLCs against the tested resistant fungal isolates. The study findings suggest that the LCZ-NLCs formulation developed in this research could be a promising topical treatment for superficial fungal infections, especially in cases of resistant infections. However, the study needs further ex vivo and in vivo tests to ensure safety and efficacy.

Development of ion-triggered in situ gel containing ketoconazole/hydroxypropyl-β-cyclodextrin for ocular delivery: in vitro and in vivo evaluation

The application of ketoconazole (KET) in ocular drug delivery is restricted by its poor aqueous solubility though its broad-spectrum antifungal activity. The aim of this study is to develop an ion-sensitive in situ gel (ISG) of KET to promote its ocular bioavailability in topical application. The solubility of KET in water was increased by complexation with hydroxypropyl-β-cyclodextrin (HPβCD), then KET-HPβCD inclusion complex (KET-IC) was fabricated into an ion-sensitive ISG triggered by sodium alginate (SA). The in vitro drug release and antifungal activities investigations demonstrated that the KET-IC-ISG formulation increased drug release and anti-fungal activities compared to pure KET. The ex vivo rabbit corneal permeation studied demonstrated higher permeability of KET-IC-ISG formulation (Papp of (6.34 ± 0.21) × 10-4 cm/h) than pure KET (Papp of (3.09 ± 0.09) × 10-4 cm/h). The cytotoxicity assay and the ocular irritation study in rabbits confirmed the KET-IC-ISG safety and well tolerance. The ocular pharmacokinetics of KET in rabbits was investigated and the results showed that the KET-IC-ISG increased its bioavailability in cornea by 47-fold. In conclusion, the KET-IC-ISG system promoted the precorneal retention, the ocular drug bioavailability and the developed formulation is a potential strategy to treat mycotic keratitis.

Nanoemulsions: Summary of a Decade of Research and Recent Advances

Nanoemulsions consist of a combination of several components such as oil, water, emulsifiers, surfactants and cosurfactants. Various techniques for producing nanoemulsions include high-energy and low-energy approaches such as high-pressure homogenization, microfluidization, jet disperser and phase inversion methods. The properties of a formulation can be influenced by elements such as the composition, concentration, size and charge of droplets, which in turn can affect the technique of manufacture. Characterization is conducted by the assessment of several factors such as physical properties, pH analysis, viscosity measurement and refractive index determination. This article offers a thorough examination of the latest developments in nanoemulsion technology, with a focus on their wide-ranging applications and promising future possibilities. It also discusses the administration of nanoemulsions through several methods.

Recent Advances in Diagnosis and Treatment Approaches in Fungal Keratitis: A Narrative Review

Fungal keratitis represents a potentially sight-threatening infection associated with poor prognosis, as well as financial burden. Novel diagnostic methods include polymerase-chain-reaction (PCR)-based approaches, metagenomic deep sequences, in vivo confocal microscopy, and antifungal susceptibility testing. The ideal therapeutic approaches and outcomes have been widely discussed in recent times, with early therapy being of the utmost importance for the preservation of visual acuity, minimizing corneal damage and reducing the scar size. However, combination therapy can be more efficacious compared to monotherapy. Understanding the pathogenesis, early diagnosis, and prevention strategies can be of great importance. In this narrative, we discuss the recent progress that may aid our understanding of the diagnosis, treatment, and prevention of mycotic keratitis.

Investigation of Luliconazole-Loaded Mucoadhesive Electrospun Nanofibers for Anticandidal Activity in the Management of Vaginal Candidiasis

In this study, we fabricated and evaluated luliconazole-loaded electrospun nanofibers for anticandidal activity in the management of vaginal candidiasis. Polycaprolactone (PCL)/gelatin nanofibers were designed by the electrospinning technique, and the Box-Behnken design (BBD) was adopted for optimization to get tailored fibers. The luliconazole (LCZ) drug was mixed into different concentrations (2.5, 5, 7.5, and 10%) of tea tree oil (TT oil) and loaded into the PCL/gelatin nanofibrous mats. The effective anticandidal potential of nanofiber samples were analyzed by the disk-diffusion method. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), XRD analysis, and in silico study were performed. The entrapment efficiency, swelling degree, mechanical strength, contact angle, mucoadhesion, drug release, and permeation study were assessed. The average diameter of the PCL/gelatin-optimized nanofiber was 153 nm. SEM reflected that the fabricated nanofibers were uniform and bead-free. FTIR and DSC analyzed the interaction and physical entrapment of the drug in the polymeric fibers. The entrapment efficiency of the drug-loaded nanofiber was found to be 89.2 ± 0.8%. Maximum swelling percentages at 4 h were 40.8, 18.9, and 14.0% and contact angles were 46.5°, 62.95°, and 65.78° for the blank, TT oil-loaded, and drug-loaded nanofiber, respectively, which indicated the hydrophilic nature of the fibers. The drug-loaded nanofiber had a high tensile strength with satisfactory mucoadhesive property that led to its adhesion to the vaginal mucosa with no tear. The drug-loaded nanofiber had a cumulative drug release of 67.7 ± 3.4% in 48 h, and the 12.8 ± 0.53 mm of zone of inhibition (ZOI) in 48 h illustrated an effective anticandidal activity. The TT oil-loaded nanofiber also exhibited a small ZOI of 4.3 ± 0.30 mm, indicating a synergistic effect to the antifungal activity of the drug-loaded nanofiber. LCZ-loaded nanofibers can emerge as a novel approach for vaginal drug delivery in the treatment of candida infection. Thus, this pharmaceutical investigation can help in formulating preclinical and clinical models.

Antifungal Efficacy of Luliconazole in an Experimental Rabbit Model of Fungal Keratitis Caused by Fusarium solani

Fungal keratitis is a corneal fungal infection that potentially leads to blindness and is mainly caused by filamentous fungi, such as Fusarium, with limited drug options available, such as natamycin and voriconazole. Therefore, this study aimed to evaluate the therapeutic effects of the imidazole antifungal drug-luliconazole-using a rabbit experimental model of fungal keratitis caused by Fusarium solani, which is the dominant causative agent of fungal keratitis. F. solani was inoculated into rabbit corneas. luliconazole 1% suspension or natamycin 5% eye drops were administered four times a day (N = 6 for each group) 3 days after inoculation. Signs were scored up to 14 days after inoculation to evaluate the efficacy of the drugs. Compared with the peak mean sign scores of the placebo control group, there was a significant decrease in the mean sign scores of both the treatment groups (P < 0.05). Sign score trends were similar between the two treatment groups. In conclusion, luliconazole demonstrated therapeutic efficacy comparable to that of natamycin in treating experimental fungal keratitis. This suggests that luliconazole can be a novel therapeutic agent for human fungal keratitis.

Development of Osthole-Loaded Microemulsions as a Prospective Ocular Delivery System for the Treatment of Corneal Neovascularization: In Vitro and In Vivo Assessments

Osthole (OST), a natural coumarin compound, has shown a significant inhibitory effect on corneal neovascularization (CNV). But, its effect on treating CNV is restricted by its water insolubility. To overcome this limitation, an OST-loaded microemulsion (OST-ME) was created to improve the drug's therapeutic effect on CNV after topical administration. The OST-ME formulation comprised Capryol-90 (CP-90), Cremophor® EL (EL-35), Transcutol-P (TSP) and water, and sodium hyaluronate (SH) was also included to increase viscosity. The OST-ME had a droplet size of 16.18 ± 0.02 nm and a low polydispersity index (0.09 ± 0.00). In vitro drug release from OST-ME fitted well to the Higuchi release kinetics model. Cytotoxicity assays demonstrated that OST-ME was not notably toxic to human corneal epithelial cells (HCECs), and the formulation had no irritation to rabbit eyes. Ocular pharmacokinetics studies showed that the areas under the concentration-time curves (AUC0-t) in the cornea and conjunctiva were 19.74 and 63.96 μg/g*min after the administration of OST-ME, both of which were 28.2- and 102.34-fold higher than those after the administration of OST suspension (OST-Susp). Moreover, OST-ME (0.1%) presented a similar therapeutic effect to commercially available dexamethasone eye drops (0.025%) on CNV in mouse models. In conclusion, the optimized OST-ME exhibited good tolerance and enhanced 28.2- and 102.34-fold bioavailability in the cornea and conjunctiva tissues compared with suspensions in rabbit eyes. The OST-ME is a potential ocular drug delivery for anti-CNV.

Development of Soft Luliconazole Invasomes Gel for Effective Transdermal Delivery: Optimization to In-Vivo Antifungal Activity

Luliconazole (LZ) is a good candidate for the treatment of fungal infection topically but has limitations, i.e., poor solubility and poor permeability to skin. Due to these limitations, multiple administrations for a long time are required to treat the inflection. The aim of the present study was to develop the invasomes (IVS) gel of LZ to improve the topical antifungal activity. The IVS was prepared by the thin-film hydration method and optimized by Box-Bhekhen design software. The optimized LZIVS (LZIVSopt) has 139.1 ± 4.32 nm of vesicle size, 88.21 ± 0.82% of entrapment efficiency, 0.301 ± 0.012 of PDI, and 19.5 mV (negative) of zeta potential. Scanning microscopy showed a spherical shape of the vesicle. FTIR spectra showed there is no interaction between the drug and lipid. Thermogram showed that the LZ is encapsulated into the LZIVS matrix. LZIVSopt gel (LZIVSopt-G3) exhibited optimum viscosity (6493 ± 27 cps) and significant spreadability (7.2 g·cm/s). LZIVSopt-G3 showed 2.47-fold higher permeation than pure LZ-gel. LZIVSopt-G3 did not show any edema or swelling in the skin, revealing that the developed formulation is non-irritant. LZIVSopt-G3 exhibited significant inhibition of the fungus infection (C. albicans) in the infected rats. The finding concluded that IVS gel is a good carrier and an attractive approach for the enhancement of topical delivery of LZ to treat the fungal infection.

Preparation of a Sunitinib loaded microemulsion for ocular delivery and evaluation for the treatment of corneal neovascularization in vitro and in vivo

Background: Corneal neovascularization (CNV) is a pathological condition that can disrupt corneal transparency, thus harming visual acuity. However, there is no effective drug to treat CNV. Sunitinib (STB), a small-molecule multiple receptor tyrosine kinase inhibitor, was shown to have an effect on CNV. The purpose of this study was to develop an STB microemulsion (STB-ME) eye drop to inhibit CNV by topical application. Methods: We successfully prepared an STB-ME by the phase inversion emulsification method, and the physicochemical properties of STB-MEs were investigated. The short-term storage stability, cytotoxicity to human corneal epithelial cells, drug release, ocular irritation, ocular pharmacokinetics and the inhibitory effect on CNV were evaluated in vitro and in vivo. Results: The optimal formulation of STB-ME is composed of oleic acid, CRH 40, Transcutol P, water and sodium hyaluronate (SH). It is a uniform spherical particle with a mean droplet size of 18.74 ± 0.09 nm and a polydispersity index of 0.196 ± 0.004. In the in vitro drug release results, STB-ME showed sustained release and was best fitted by a Korsmeyer-Peppas model (R ² = 0.9960). The results of the ocular pharmacokinetics in rabbits showed that the formulation containing SH increased the bioavailability in the cornea (2.47-fold) and conjunctiva (2.14-fold). STB-ME (0.05% and 0.1%), administered topically, suppressed alkali burn-induced CNV in mice more effectively than saline, and high-dose (0.1%) STB-ME had similar efficacy to dexamethasone (0.025%). Conclusion: This study provides a promising formulation of STB-ME for the inhibition of CNV by topical administration, which has the excellent characteristics of effectiveness, sustained release and high ocular bioavailability.

Innovative Aqueous Nanoemulsion Prepared by Phase Inversion Emulsification with Exceptional Homogeneity

Formulating low-solubility or low-permeability drugs is a challenge, particularly with the low administration volumes required in intranasal drug delivery. Nanoemulsions (NE) can solve both issues, but their production and physical stability can be challenging, particularly when a high proportion of lipids is necessary. Hence, the aim of the present work was to develop a NE with good solubilization capacity for lipophilic drugs like simvastatin and able to promote the absorption of drugs with low permeability like fosphenytoin. Compositions with high proportion of two lipids were screened and characterized. Surprisingly, one of the compositions did not require high energy methods for high droplet size homogeneity. To better understand formulation factors important for this feature, several related compositions were evaluated, and their relative cytotoxicity was screened. Optimized compositions contained a high proportion of propylene glycol monocaprylate NF, formed very homogenous NE using a low-energy phase inversion method, solubilized simvastatin at high drug strength, and promoted a faster intranasal absorption of the hydrophilic prodrug fosphenytoin. Hence, a new highly homogeneous NE obtained by a simple low-energy method was successfully developed, which is a potential alternative for industrial application for the solubilization and protection of lipophilic actives, as well as (co-)administration of hydrophilic molecules.