Voriconazole-loaded self-nanoemulsifying drug delivery system (SNEDDS) to improve transcorneal permeability

Ultrasonic Preparation of Nano-CaCO3 Templates and Hollow Mesoporous SiO2 Nanoparticles for Voriconazole Loading

CaCO3 nanoparticles (nano-CaCO3) as nano-templates were prepared using CaCl2 and Na2CO3 solutions under controlled sonication (19.5 kHz). Using the same ultrasonic device, subsequently, hollow mesoporous silica nanoparticles (HMSNs) were obtained by the hard template of nano-CaCO3. HMSNs were selected as carriers for the antifungal drug voriconazole (VOR) loading to overcome poor water solubility. Three-dimensional CaCO3 nanosheets HMSNs were obtained under gentle sonication. Three-dimensional CaCO3 nanosheets of 24.5 nm (hydrodynamic diameter) were obtained under 17.6 W for 3 min. HMSNs were synthesized by double-template method with nano-CaCO3 as the hard template. Transmission electron microscopy measurements showed that the prepared HMSNs possess hollow structures with particle size between 110 and 120 nm. Nitrogen physisorption at -196 °C revealed that the HMSNs had high surface area (401.57 m2/g), high pore volume (0.11 cm3/g), and uniform pore size (2.22 nm) that facilitated the effective encapsulation of VOR in the HMSNs. The loading capacity of VOR (wt%) on the HMSNs was 7.96%, and the total VOR release amount of VOR-HMSNs material was 71.40% at 480 min. The kinetic model confirmed that the release mechanism of HMSNs nanoparticles followed Fickian diffusion at pH = 7.4 and 37 °C. Moreover, the cumulative VOR release at 42 °C (86.05%) was higher than that at 37 °C (71.40%). The cumulative release amount of VOR from the VOR-HMSNs material was 92.37% at pH = 5.8 at the same temperature. Both nano-CaCO3 templates and HMSNs were prepared by sonication at 19.5 kHz. The as-prepared HMSNs can effectively encapsulate VOR and released drug by Fickian diffusion.

Triamcinolone-loaded self nano-emulsifying drug delivery systems for ocular use: An alternative to invasive ocular surgeries and injections

Inflammation of the posterior segment of the eye is a severe condition and hard to cure as delivery of drugs to the inflammation site is inefficient. Currently, the primary treatment approach is ocular surgery or invasive ocular injections. Herein, we designed and developed a topically self nano-emulsifying drug delivery system (SNEDDs) to deliver triamcinolone acetonide (TCA) to the posterior segment of the eye. A screening based on TCA solubility was conducted on each excipient followed by preparation of various formulations using different ratios of the selected excipients. Vesicles of optimized SNEDDs had less than 100 nm size and spherical morphology. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay showed self-emulsified vesicles have relatively high safety on retinal pigment epithelium (RPE) cell line. Furthermore, efficient cellular uptake of coumarin 6-loaded SNEDDs in RPE using confocal laser scanning microscopy (CLSM) was confirmed. In addition, an in-vivo study using hematoxylin and eosin (H&E) staining revealed that 14 days of topical treatment of albino rabbit eyes with TCA-loaded SNEDDs was safe and no sign of tissue destruction and inflammation was detected in different parts of the eye sections including cornea, sclera, retina, and optic nerve. Also, the CLSM images from topically treated eyes with coumarin 6 (a hydrophobic, fluorescent drug model) loaded SNEDDs, showed that the optimized SNEDDs could properly penetrate toward the posterior segments of the eye especially the retina, posterior parts of the choroid, and sclera. Considering the outstanding results obtained by ocular tissue penetration and low toxicity, prepared SNEDDs, have the potential to be used as a topical administration for treating posterior segment disorders of the eye through an utterly non-invasive route and TCA-loaded SNEDDs could be an alternative for TCA intravitreal and intra conjunctival injections.

Cationic microemulsion of voriconazole for the treatment of fungal keratitis: in vitro and in vivo evaluation

Aim: This investigation aimed to develop a voriconazole-loaded chitosan-coated cationic microemulsion (CVME) to treat fungal keratitis. Methods: Microemulsions were prepared using water titration, and the optimized microemulsion was coated with chitosan to prepare CVME. The physicochemical parameters, ocular irritation potential, in vitro antifungal efficacy and in vitro release studies were performed. The in vivo antifungal efficacy study was conducted in a fungal infection-induced rabbit eye model. Results: The developed CVME displayed acceptable physicochemical properties and excellent mucoadhesive behavior and showed a sustained release profile. Ex vivo and in vivo studies concluded that higher permeability and improved antifungal efficacy were observed for CVME than drug suspension (DS). Conclusion: The prepared CVME7 is a viable alternative to treating fungal keratitis with existing approaches.

The Effect of High-Pressure Homogenization Conditions on the Physicochemical Properties and Stability of Designed Fluconazole-Loaded Ocular Nanoemulsions

The growing interest in high-energy emulsification is a result of its scalability, which is important from an industrial perspective and allows for a more reproducible and efficient production of pharmaceutical formulations. The aim of this study was to evaluate the effect of composition, mainly a fixed surfactant/cosurfactant (Smix) ratio, their concentration, and the parameters of high-pressure homogenization (HPH) processing on the quality and stability of ophthalmic fluconazole-loaded nanoemulsions. After a physicochemical analysis of nanoemulsions containing 20% w/w of oil, as optimal conditions for the HPH process, three cycles at a pressure of 1000 bar were established, obtaining formulations with an average droplet diameter size in the range of 80.63-129.68 nm and PDI values below 0.25. While it was expected that an increasing cosurfactant concentration decreased the droplet size, in the case of formulations containing Tween 20 and 10% w/w of cosurfactants, "over-processing" was observed, identified by the droplet size and polydispersity index increase. Consecutively, the selected formulations were evaluated for in vitro drug release in Franz's cell, antifungal activity, and 30-day stability using NMR spectroscopy. An antifungal activity test showed no significant difference in the antifungal activity between optimal fluconazole-loaded nanoemulsions and a 0.3% aqueous drug solution, but previously, research showed that prepared formulations were characterized by a higher viscosity and satisfactory prolonged release compared to a control. In a 30-day stability study, it was observed that higher HLB values of the used surfactants decreased the stability of the formulations in the following order: Kolliphor EL, Tween 80, Tween 20. The NMR spectra confirmed that Kolliphor EL-based formulations ensured the higher stability of the nanoemulsion composition in comparison to Tween 80 and a better stabilizing effect of propylene glycol as a cosurfactant in comparison to PEG 200. Therefore, the optimization of HPH technology should be focused on the selection of Smix and the Smix:oil ratio in order to prepare stable formulations of high quality.

Microscopic and Biopharmaceutical Evaluation of Emulsion and Self-Emulsifying Oil with Cyclosporine

Among the currently available commercial eye drops with cyclosporine A (Cs) there is a lack of long-acting dosage forms and products with a concentration of the drug substance higher than 0.1%, although Cs is widely used in ophthalmology. The aim of the research was to conduct the microscopic and biopharmaceutical evaluation of two formulations, an emulsion (EM) and a self-emulsifying oil (SEO), both with 0.5% of Cs, proposed for use in eye drops, and the comparison of both. SEO eye drops with Cs or any other drug substance are currently not available as marketed products, and the highest concentration of Cs in the ocular emulsion is only 0.1%. The microscopic evaluation of the emulsion and the SEO after emulsification with water was carried out using a high-resolution digital microscopy. The properties of both preparations were compared using the high dynamic range function or optical shadow effect mode. Images in the 3D composition mode were also recorded. The in vivo study of the Cs formulations was performed on male albino rabbits. The eye tolerance of the preparations was assessed using the ocular irritation test, which is a modified Draize test. Placebo carriers (without the drug substance) were also subjected to irritation testing. The concentration of Cs in the tissues (cornea and conjunctiva) and fluids (tear fluid and aqueous humor) of the rabbit eye was determined after multiple instillations of Cs-EM or Cs-SEO. The tested preparations were compared using the digital microscopy technique, which highlights the features of the formulations and eliminates the risk of unnoticeable properties that are difficult to observe in classical optical microscopy. Both tested Cs-loaded formulations are classified as practically non-irritating. There were also no significant differences when testing the placebo carriers. After a topical administration, Cs was widely distributed in all tissues (e.g., in cornea 1.3 ng/mg and 1.0 ng/mg) and fluids of the eye (e.g., in tear fluid 11.6 µg/mL and 4.3 µg/mL), after the administration of Cs-SEO and Cs-EM, respectively. The obtained results allow us to recognize both tested formulations, the emulsion and the self-emulsifying oil with 0.5% Cs content, as carriers safe for ophthalmic use and effective in delivering the drug substance to the structures of the eye.

Toxicity of simultaneous intrastromal and intracameral injection of voriconazole on corneal endothelium in a rabbit model

PURPOSE

To investigate the toxicity of repeated simultaneous intrastromal and intracameral injections of voriconazole in corneal endothelial cells in a rabbit model.

METHODS

Thirty-six eyes of 18 New Zealand white rabbits (six eyes per group) were divided into 6 groups according to the concentration of voriconazole (Group A, 0%; Group B, 0.05%; Group C, 0.1%; Group D, 0.25%; Group E, 0.5%; Group F, 1%). A combination of intrastromal and intracameral voriconazole injections were administrated to the eyes of each group three times on days 0, 3, and 7. Corneal clouding grades and central corneal thickness (CCT) were examined on days 0, 3, 7, 10, and 14. The endothelial cell counts (ECC) were measured on days 0 and 14. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed on day 14.

RESULTS

Group F (1%) showed more severe corneal clouding than the other groups (Groups A-E) from day 7 (p < 0.05, respectively). There were no significant differences in CCT and ECC among the six groups at any time point (p > 0.05, respectively). SEM revealed blurring of the cell border and loss of microvilli at concentrations ≥0.25% (Groups D-F). TEM revealed microstructural changes in endothelial cells at concentrations ≥0.1% (Groups C-F), and multiple vacuoles were observed at a concentration of 1% voriconazole (Group F).

CONCLUSIONS

Repeated simultaneous intrastromal and intracameral voriconazole injections at a concentration of 0.1% or higher induced microstructural endothelial damage in rabbit corneal endothelial cells.

Nanotechnology-Based Approaches for Voriconazole Delivery Applied to Invasive Fungal Infections

Invasive fungal infections increase mortality and morbidity rates worldwide. The treatment of these infections is still limited due to the low bioavailability and toxicity, requiring therapeutic monitoring, especially in the most severe cases. Voriconazole is an azole widely used to treat invasive aspergillosis, other hyaline molds, many dematiaceous molds, Candida spp., including those resistant to fluconazole, and for infections caused by endemic mycoses, in addition to those that occur in the central nervous system. However, despite its broad activity, using voriconazole has limitations related to its non-linear pharmacokinetics, leading to supratherapeutic doses and increased toxicity according to individual polymorphisms during its metabolism. In this sense, nanotechnology-based drug delivery systems have successfully improved the physicochemical and biological aspects of different classes of drugs, including antifungals. In this review, we highlighted recent work that has applied nanotechnology to deliver voriconazole. These systems allowed increased permeation and deposition of voriconazole in target tissues from a controlled and sustained release in different routes of administration such as ocular, pulmonary, oral, topical, and parenteral. Thus, nanotechnology application aiming to delivery voriconazole becomes a more effective and safer therapeutic alternative in the treatment of fungal infections.

Engineering Advanced Drug Delivery Systems for Dry Eye: A Review

Dry eye disease (DED) is a widespread and frequently reported multifactorial ocular disease that not only causes ocular discomfort but also damages the cornea and conjunctiva. At present, topical administration is the most common treatment modality for DED. Due to the existence of multiple biological barriers, instilled drugs generally exhibit short action times and poor penetration on the ocular surface. To resolve these issues, several advanced drug delivery systems have been proposed. This review discusses new dosage forms of drugs for the treatment of DED in terms of their characteristics and advantages. Innovative formulations that are currently available in the market and under clinical investigation are elaborated. Meanwhile, their deficiencies are discussed. It is envisioned that the flourishing of advanced drug delivery systems will lead to improved management of DED in the near future.

Functional Excipients and Novel Drug Delivery Scenario in Self-nanoemulsifying Drug Delivery System: A Critical Note

Lipid-based formulations have emerged as prospective dosage forms for extracting the therapeutic effects of existing lipophilic compounds and novel chemical entities more efficiently. Compared to other excipients, lipids have the added benefit of enhancing the bioavailability of lipophilic and highly metabolizable drugs due to their unique physicochemical features and similarities to in vivo components. Furthermore, lipids can minimize the needed dose and even the toxicity of drugs with poor aqueous solubility when employed as the primary excipient. Hence, the aim of the present review is to highlight the functional behavior of lipid excipients used in SNEDD formulation along with the stability aspects of the formulation in vivo. Moreover, this review also covered the importance of SNEDDS in drug delivery, the therapeutic and manufacturing benefits of lipids as excipients, and the technological advances made so far to convert liquid to solid SNEDDS like melt granulation, adsorption on solid support, spray cooling, melt extrusion/ spheronization has also highlighted. The mechanistic understanding of SNEDD absorption in vivo is highly complex, which was discussed very critically in this review. An emphasis on their application and success on an industrial scale was presented, as supported by case studies and patent surveys.

Voriconazole-Cyclodextrin Supramolecular Ternary Complex-Loaded Ocular Films for Management of Fungal Keratitis

Fungal keratitis is one of the leading causes of ophthalmic mycosis affecting the vision due to corneal scarring. Voriconazole (VRC) is the most preferred azole antifungal agent for treating ocular mycotic infections. Ocular drug delivery is challenging due to the shorter corneal residence time of the formulation requiring frequent administration, leading to poor patient compliance. The present study aimed at improving the solubility, transcorneal permeation, and efficacy of voriconazole via the formation of cyclodextrin-based ternary complexes and incorporation of the complex into mucoadhesive films. A phase solubility study suggested a ∼14-fold improvement in VRC solubility, whereas physicochemical characterization confirmed the inclusion of VRC in the cyclodextrin inner cavity. In silico docking studies were performed to predict the docking conformation and stability of the inclusion complex. Complex-loaded films showed sustained release of voriconazole from the films and improved transcorneal permeation by ∼4-fold with an improved flux of 8.36 μg/(cm² h) for ternary complex-loaded films compared to 1.86 μg/(cm² h) for the pure VRC film. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and hen's egg-chorioallantoic membrane test (HET-CAM) assays confirmed that the complexes and ocular films were nonirritant and safe for ocular administration. The antifungal study performed using Aspergillus fumigatus and Fusarium oxysporum suggested improved antifungal activity compared to the pure drug film. In conclusion, the supramolecular cyclodextrin ternary complex proved to be a promising strategy for enhancing the solubility and permeability and augmenting the antifungal activity of voriconazole in the management of fungal keratitis.

Maleimide-functionalized phospholipid/Pluronic F127 mixed micelles for efficient ophthalmic delivery of voriconazole against Candida albicans

Drugs that are topically applied on the eyes have low bioavailability, which has always been an important problem. In this study, maleimide functionalized, voriconazole (VCZ) loaded mixed micelles (Mal-VCZ-MM) were designed. Pluronic F127 and phospholipid were used as materials, and maleimide was used as an adhesive. The prepared Mal-VCZ-MM was nearly spherical with a particle size of 84.45 ± 1.39 nm and a zeta potential of - 20.3 ± 0.29 mV. The encapsulation efficiency of Mal-VCZ-MM was 95.33 ± 0.06%, and it had high stability with a critical micelle concentration value of 1.28 × 10^-4 mg/mL. CCK-8 assay showed that its cytotoxicity was lower than that of free VCZ solution (VCZ-Sol). Both quantitative and qualitative analyses of the HCE-T cellular uptake showed that the cellular internalization of Mal-C6-MM was significantly stronger than that of C6-MM. The endocytosis pathway was macropinocytosis-mediated, cavernous-mediated, and energy-dependent. In vitro results against Candida albicans showed that the diameters of the antifungal inhibition zones of VCZ-Sol, VCZ-MM, and Mal-VCZ-MM were 15.5 ± 0.50 mm, 24.0 ± 0.71 mm, and 31.5 ± 1.12 mm, respectively. The antifungal effect of Mal-VCZ-MM was significantly higher than that of VCZ-Sol and VCZ-MM (P < 0.001). This study shows that Mal-VCZ-MM is a highly effective hydrophobic ophthalmic drug-delivery carrier that can improve the therapeutic effect of the drug.

Lipid-based emulsion drug delivery systems - a comprehensive review

Lipid-based emulsion system - a subcategory of emulsion technology, has emerged as an enticing option to improve the solubility of the steadily rising water-insoluble candidates. Along with enhancing solubility, additional advantages such as improvement in permeability, protection against pre-systemic metabolism, ease of manufacturing, and easy to scale-up have made lipid-based emulsion technology very popular among academicians and manufacturers. The present article provides a comprehensive review regarding various critical properties of lipid-based emulsion systems, such as microemulsion, nanoemulsion, SMEDDS (self microemulsifying drug delivery system), and SNEDDS (self nanoemulsifying drug delivery system). The present article also explains in detail the similarities and differences between them, the stabilization mechanism, methods of preparation, excipients used to prepare them, and evaluation techniques. Subtle differences between nearly related terminologies such as microemulsion and nanoemulsion, SMEDDS, and SNEDDS are also explained in detail to clarify the basic differences. The present article also gives in-depth information regarding the chemical structure of various lipidic excipients, various possible chemical modifications to modify their inherent properties, and their regulatory status for rational selection.

Efficacy of Voriconazole Corneal Intrastromal Injection for the Treatment of Fungal Keratitis

Purpose

To evaluate efficacy and safety of novel tricyclic corneal stroma injection (TCSI) voriconazole for the treatment of fungal keratitis.

Methods

This retrospective cohort study included data of 57 patients (57 eyes) with fungal keratitis. The TCSI group consisted of 27 patients (27 eyes) who were injected voriconazole once via TCSI procedure within one week after enrollment, in addition to conventional antifungal treatment. The control group consisted of 30 patients (30 eyes) who were treated using conventional antifungal treatment modalities. The outcome measures consist of the 3-week and 3-month best-corrected visual acuity (BCVA) values and size of infiltrate or scar, time to re-epithelialization, corneal perforation rate and/or therapeutic penetrating keratoplasty (TPK) requirement, the preoperative and post-TCSI corneal endothelial cell density (ECD), and the intraocular pressure (IOP) of the treated eye and the respective contralateral eye.

Results

There were no significant differences in the baseline demographic and clinical characteristics between the two groups. 3 weeks and 3 months after enrollment, the TCSI group exhibited an increase in visual acuity (P < 0.05), and there was no significant difference in the size of infiltrate or scar between two groups (P > 0.05). Time to re-epithelialization was shorter in the TCSI group than in the control group (P < 0.05). There was no statistically significant difference between corneal ECD on the day before and 7 days after TCSI and the IOP of treated and contralateral healthy eyes on the day before and 1 day, 3 days, 7 days, and 1 month after TCSI (P > 0.05). The difference in the risk of perforation and/or TPK requirement was not statistically significant between two groups (P > 0.05).

Conclusion

Localized injection of voriconazole using TCSI may be a minimally invasive, safe, and effective adjuvant treatment modality for fungal keratitis.

Gamma sterilization and in vivo evaluation of cationic nanostructured lipid carriers as potential ocular delivery systems for antiglaucoma drugs

Solid lipid nanoparticles and nanostructured lipid carriers showed promising results for enhancement of ocular bioavailability of drugs with poor corneal permeability. One of these drugs is methazolamide, which is an orally administered carbonic anhydrase inhibitor for glaucoma treatment. However, sterilization by autoclaving may result in loss of the physical properties of lipid nanoparticles such as particle size and surface charge. Here, we evaluated gamma radiation as an alternative sterilization method. Methazolamide loaded nanostructured lipid carriers were optimized using 2³ factorial design. Optimized formulations contained 6% lipid (85% solid lipid (Cetostearyl alcohol and glyceryl behenate) and 15% oil either medium chain triglycerides or isopropyl myristate) stabilized by 2% polysorbate 80 and 0.15% stearylamine. Nanoparticles were cationic, smaller than 500 nm, and had an entrapment efficiency of about 30%. They released methazolamide within 8 hours and showed a 5-fold enhanced reduction in intraocular pressure compared to methazolamide solution. Gamma sterilization was superior to autoclaving in preserving entrapped methazolamide, size, and surface charge of lipid nanoparticles. These findings demonstrate that gamma radiation is a viable alternative to autoclaving for sterilizing lipid nanoparticles. Moreover, this proves that nanostructured lipid carriers enhance pharmacological response of topically administered methazolamide for treating glaucoma.

Formulation and optimization of microsponge-loaded emulgel to improve the transdermal application of acyclovir-a DOE based approach

The cutaneous penetration of acyclovir from the conventional topical formulations such as cream and ointments is poor due to low water solubility and low octanol buffer partition coefficient of the drug. The present investigation was aimed to prepare acyclovir-loaded microsponge-based emulgel to improve its topical delivery. The microsponges were prepared by the quasi-emulsion diffusion method. The central composite design was employed to investigate the effect of changes in various formulation and process parameters on critical product attributes. Homogenization speed (X1), drug/polymer ratio (X2), and concentration of PVA (X3) were selected as independent variables while particle size,b% yield, % drug loading efficiency, % entrapment efficiency, the drug released at 0.25 h and 6 h were selected as response variables. The regression analysis proved a significant effect of all the independent variables on the dependent variables (p < 0.05). All the designed batches released more than 40% drug in less than 1 h and were also able to sustain the drug release for more than 6 h. Based on the solution suggested by the software, the optimized batch was prepared with 1000-rpm homogenization speed, 1.6:1 drug/polymer ratio, and 0.088% of PVA. The optimized microsponge-loaded emulgel had acceptable viscosity (10,897 to 12,416 centipoise), spreadability (32.5 to 36.57 g × cm/s), pH (between 6 and 7), and drug content (93 to 95%). The results of the ex vivo permeation study proved significant improvement in drug permeation from optimized microsponge-loaded emulgel compared to the marketed formulation (f2 < 50).