Besifloxacin-loaded ocular nanoemulsions: design, formulation and efficacy evaluation

The synergistic effect of α-tocopherol and phloretin-loaded nanoemulsions on improvement of the stability, antioxidant, and tyrosinase inhibitory potentiality

The purpose of this study was to prepare and evaluate the formulation of nanoemulsions (NEs) to encapsulate phloretin (PT) to improve its stability, antioxidant, and tyrosinase inhibitory competence. The aim of this study was to improve the stability, antioxidant, and tyrosinase inhibitory effects of PT via NEs. The formulations were prepared using low energy emulsification method for PT-VE-NEs, α-tocopherol (Vitamin E) and medium chain triglycerides (MCT) were used as the oil phase, and Tween 60 was used as the emulsifier and PEG-400 as the co-emulsifier. The droplet size and zeta potential of oil-in-water NEs were evaluated using dynamic light scattering. The PT-VE-NEs were also characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The mean droplet diameter was 14.85 ± 0.14 nm, with a zeta potential of -2.47 ± 0.51 mV. Fourier transform infrared spectroscopy revealed the formation of molecular interactions in the NEs formulations. PT-VE-NEs size was maintained the same during the in vitro digestion study. The particle size of PT-VE-NE remained stable during in vitro digestion. The addition of VE significantly improved the antioxidant, tyrosinase inhibitory effects, as well as thelion and physical stability of PT-VE-NE. The results revealed that NEs is a promising strategy to improve the functionality and stability of PT and VE. PT-VE-NEs will be applied for the preservation of fruits.

Enhancing the efficacy of fluconazole against Leishmania major: Formulation and evaluation of FLZ-nanoemulsions for topical delivery

BACKGROUND

Cutaneous Leishmaniasis (CL) remains a significant public health concern, particularly in the tropical and subtropical regions. Present treatment options for CL such as Fluconazole (FLZ) face limitations, including low solubility and bioavailability. This study aimed to address these challenges by investigating the use of nano-emulsions (NEs) to enhance the efficacy of FLZ against Leishmania major(L.major).

MATERIALS AND METHODS

FLZ-NEs were formulated with oleic acid, Tween-20, and ethanol using low-energy emulsification at various surfactant/co-surfactant ratios. Subsequently, a comprehensive analysis was conducted to assess the physicochemical characteristics of the samples. This analysis encompassed stability, zeta potential, pH, viscosity, refractive index, and droplet size. We then studied the anti-parasitic properties of these optimized FLZ-NEs both in vitro and in vivo.

RESULTS

The selected nano-emulsion (NE) formulation (2 % oleic acid, 20 % Tween 20, 10 % ethyl alcohol) showcased desirable properties like small droplet size (10.51 ± 0.24 nm), low dispersity (0.19 ± 0.03), and zeta potential value (- 0.41 ± 0.17 mV), key for stability and targeted drug delivery. This optimal formulation translated into remarkable efficacy. In vitro, FLZ-NEs demonstrated a threefold increase in their ability to combat promastigotes and a remarkable thirtyfold increase in their ability to combat amastigotes. Additionally, they demonstrated a ninefold advantage in their ability to specifically target parasites within infected macrophages, thereby attacking the infection site. These promising in vitro results translated into improved outcomes in vivo. Compared to other chemicals studied, FLZ-NE-treated mice showed decreased disease severity, weight growth, and quicker ulcer healing. It was further supported by histopathological research, which showed reduced tissue damage linked to Leishmania infection.

CONCLUSION

These findings show the potential of nanotechnology-based drug delivery in improving anti-leishmanial treatment.

Self-Microemulsifying Drug Delivery System to Enhance Oral Bioavailability of Berberine Hydrochloride in Rats

Berberine hydrochloride (BH) is a versatile bioactive compound derived from the plants of the Berberis genus, known for its various pharmacological effects. However, its oral bioavailability is low due to its high hydrophilicity and limited permeability. To enhance its clinical efficacy and oral bioavailability, this study designed and prepared a BH-loaded self-microemulsifying drug delivery system (BH-SMEDDS), and characterized its in vitro and in vivo properties. Firstly, the optimal formulation of BH-SMEDDS was selected using solubility evaluations, pseudo-ternary phase diagrams, and particle size analysis. The formulation containing 55% Capmul MCM, 22.5% Kolliphor RH 40, and 22.5% 1,2-propanediol was developed. BH-SMEDDS exhibited stable physicochemical properties, with an average particle size of 47.2 ± 0.10 nm and a self-emulsification time of 26.02 ± 0.24 s. Moreover, in vitro dissolution studies showed significant improvements in BH release in simulated intestinal fluid, achieving 93.1 ± 2.3% release within 300 min. Meanwhile, BH-SMEDDS did not exhibit cytotoxic effects on the Caco-2 cells. Additionally, BH-SMEDDS achieved a 1.63-fold increase in oral bioavailability compared to commercial BH tablets. Therefore, SMEDDS presents a promising strategy for delivering BH with enhanced oral bioavailability, demonstrating significant potential for clinical application.

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.

PLGA Nanoparticles Containing Natural Flavanones for Ocular Inflammation

Flavanones are natural compounds that display anti-inflammatory activity. The aim of this work was to prepare PLGA nanoparticles (NPs) containing natural flavanones I ((2S)-5,7-dihydroxy-6-methyl-8-(3-methyl-2-buten-1-il)-2-phenyl-2,3-dihydro-4H-1-Benzopyran-4-one) and II (2S)-5,7-dihydroxy-2-(4'-methoxyphenyl)-6-methyl-8-(3-methyl-2-buten-1-yl)-2,3-dihydro-4H-1-Benzopyran-4-one) (NP I and NP II, respectively) so as to evaluate their potential for topical anti-inflammatory ocular therapy. An in silico study was carried out using the Molinspiration® and PASS Online web platforms before evaluating the in vitro release study and the ex vivo porcine cornea and sclera permeation. The HPLC analytical method was also established and validated. Finally, the in vitro anti-inflammatory efficacy of NPs was studied in the HCE-2 model. The flavanones I and II could be released following a kinetic hyperbolic model. Neither of the two NPs was able to permeate through the tissues. NP I and NP II were found to be respectful of any changes in the tissues' morphology, as evidenced by histological studies. In HCE-2 cells, NP I and NP II were not cytotoxic at concentrations up to 25 µM. NP I showed higher anti-inflammatory activity than NP II, being able to significantly reduce IL-8 production in LPS-treated HCE-2 cells. In summary, ocular treatment with NP I and NP II could be used as a promising therapy for the inhibition of ocular inflammation.

Enhancement of ocular anti-glaucomic activity of agomelatine through fabrication of hyaluronic acid modified-elastosomes: formulation, statistical optimisation, in vitro characterisation, histopathological study, and in vivo assessment

AIM

The aim of this manuscript was to fabricate agomelatine (AGM) loaded elastosomes to improve its corneal permeation and ocular bioavailability. AGM is a biopharmaceutical classification system (BCS) class II with low water solubility and high membrane permeability. It has a potent agonistic action on melatonin receptors, so it is used for glaucoma treatment.

METHODS

Elastosomes were made using modified ethanol injection technique according to a 22 × 41 full factorial design. The chosen factors were: edge activators (EAs) type, surfactant percent (SAA %w/w), and cholesterol:surfactant ratio (CH:SAA ratio). The studied responses were encapsulation efficiency percent (EE%), mean diameter, polydispersity index (PDI), zeta potential (ZP), percentage of drug released after two hours (Q2h%), and 24 hours (Q24h%).

RESULTS

The optimum formula with the desirability of 0.752 was composed of Brij98 as EA type, 15%w/w SAA%, and 1:1 CH:SAA ratio. It revealed EE% of 73.22%w/v and mean diameter, PDI, ZP, Q2h%, and Q24h% values of 484.25 nm, 0.31, -30.75 mV, 32.7%w/v, and 75.6%w/v, respectively. It demonstrated acceptable stability for three months and superior elasticity than its conventional liposome. The histopathological study ensured the tolerability of its ophthalmic application. Also, it was proven to be safe from the results of the pH and refractive index tests. The in vivo pharmacodynamic parameters of the optimum formula revealed dominance in a maximum % decrease in intraocular pressure (IOP), the area under the IOP response curve, and mean residence time with the value of 82.73%w/v, 820.69%h, and 13.98 h compared to that of the AGM solution (35.92%w/v, 181.30%h, and 7.52 h).

CONCLUSIONS

Elastosomes can be a promising option to improve AGM ocular bioavailability.

Ophthalmic nano-bioconjugates: critical challenges and technological advances

Ophthalmic disease can cause permanent loss of vision and blindness. Easy-to-administer topical and systemic treatments are preferred for treating sight-threatening disorders. Typical ocular anatomy makes topical and systemic ophthalmic drug delivery challenging. Various novel nano-drug delivery approaches are developed to attain the desired bioavailability in the eye by increasing residence time and improved permeability across the cornea. The review focuses on novel methods that are biocompatible, safe and highly therapeutic. Novelty in nanocarrier design and modification can overcome their drawbacks and make them potential drug carriers for eye disorders in both the anterior and posterior eye segments. This review briefly discussed technologies, patented developments, and clinical trial data to support nanocarriers' use in ocular drug delivery.

Investigating the Effectiveness of Difluprednate-Loaded Core-Shell Lipid-Polymeric Hybrid Nanoparticles for Ocular Delivery

Uveitis is a sight-threatening disease that causes inflammation in the uvea; difluprednate (DFB) is the first approved drug molecule for postoperative pain, inflammation, and endogenous uveitis. Complex ocular physiology and structure make it difficult to deliver drugs to the eye. Increased permeation and retention in the layer of the eye are required to improve the bioavailability of ocular drugs. In the current research investigation, DFB-loaded lipid polymer hybrid nanoparticles (LPHNPs) were designed and fabricated to enhance the corneal permeation and sustained release of DFB. A well-established two-step approach was used to fabricate the DFB-LPHNPs, comprising of Poly-Lactic-co-Glycolic Acid (PLGA) core that entrapped the DFB and DFB loaded PLGA NPs covered by lipid shell. The manufacturing parameters were optimized for the preparation of DFB-LPHNPs; the optimal DFB-LPHNPs showed a mean particle size of 117.3±2.9 nm, suitable for ocular administration and high entrapment efficiency of 92.45 ± 2.17 % with neutral pH (7.18 ±0.02) and isotonic Osmolality (301±3 mOsm/kg). Microscopic examination confirms the core-shell morphological structure of DFB-LPHNPs. The prepared DFB-LPHNPs were extensively characterized using spectroscopic techniques and physicochemical characterization, which confirms the entrapment of the drug and the formation of the DFB-LPHNPs. The confocal laser scanning microscopy studies revealed that Rhodamine B-loaded LPHNPs were penetrated into stromal layers of the cornea in ex-vivo conditions. The DFB-LPHNPs showed a sustained release pattern in simulated tear fluid and 4- folds enhanced permeation of DFB as compared to pure DFB solution. The ex-vivo histopathological studies revealed that DFB-LPHNPs didn't cause any damage or no alteration in the cellular structure of the cornea. Additionally, the results of the HET-CAM assay confirmed that the DFB-LPHNPs were not toxic for ophthalmic administration.

A Micro-Configured Multiparticulate Reconstitutable Suspension Powder of Fixed Dose Rifampicin and Pyrazinamide: Optimal Fabrication and In Vitro Quality Evaluation

The scarcity of age-appropriate pharmaceutical formulations is one of the major challenges impeding successful management of tuberculosis (TB) prevalence in minors. To this end, we designed and assessed the quality of a multiparticulate reconstitutable suspension powder containing fixed dose rifampicin and pyrazinamide (150 mg/300 mg per 5 mL) which was prepared employing solid−liquid direct dispersion coupled with timed dehydration, and mechanical pulverization. The optimized formulation had a high production yield (96.000 ± 3.270%), displayed noteworthy powder flow quality (9.670 ± 1.150°), upon reconstitution the suspension flow property was non-Newtonian and was easily redispersible with gentle manual agitation (1.720 ± 0.011 strokes/second). Effective drug loading was attained for both pyrazinamide (97.230 ± 2.570%w/w) and rifampicin (97.610 ± 0.020%w/w) and drug release followed a zero-order kinetic model (R2 = 0.990) for both drugs. Microscopic examinations confirmed drug encapsulation efficiency and showed that the particulates were micro-dimensional in nature (n < 700.000 µm). The formulation was physicochemically stable with no chemically irreversible drug-excipient interactions based on the results of characterization experiments performed. Findings from organoleptic evaluations generated an overall rating of 4.000 ± 0.000 for its attractive appearance and colour 5.000 ± 0.000 confirming its excellent taste and extremely pleasant smell. Preliminary cytotoxicity studies showed a cell viability above 70.000% which indicates that the FDC formulation was biocompatible. The optimized formulation was environmentally stable either as a dry powder or reconstituted suspension. Accordingly, a stable and palatable FDC antimycobacterial reconstitutable oral suspension powder, intended for flexible dosing in children and adolescents, was optimally fabricated.

Preparation and in vitro and in vivo evaluation of an isoliquiritigenin-loaded ophthalmic nanoemulsion for the treatment of corneal neovascularization

Isoliquiritigenin (ISL), as a natural flavonoid, has been proven to have therapeutic potential for corneal neovascularization (CNV) treatment; however, its therapeutic use is restricted due to its poor aqueous solubility and limited bioavailability. To overcome these limitations, a novel ISL-loaded nanoemulsion (ISL-NE) was designed for inhibiting CNV in this study. ISL-NE formulation was composed of propylene glycol dicaprylate (PGD), Cremophor® EL (EL35), polyethylene glycol 400 (PEG 400) and adding water with sodium hyaluronate, its particle size was 34.56 ± 0.80 nm with a low polydispersity index of less than 0.05, which suggested a narrow size distribution. The results demonstrated that ISL-NE released higher and permeated more drug than ISL suspension (ISL-Susp) in in vitro drug release and ex vivo corneal permeation study. ISL-NE showed no cytotoxicity in human corneal epithelial cells toxicity study, which was consistent with the result of ocular irritation study in rabbit eyes. ISL-NE had bioavailability 5.76-fold, 7.80-fold and 2.13-fold higher than ISL-Sups in tears, cornea and aqueous humor after a single dose of ISL-NE, respectively. Furthermore, the efficacy of ISL-NE treatment (0.2% ISL) was comparable to that of dexamethasone treatment (0.025%) in the inhibition of CNV in mice model. Enzyme-linked immunosorbent assay (ELISA) showed that the expressions of corneal vascular endothelial growth factor (VEGF-A) and matrix metalloproteinase (MMP-2) were decreased. In conclusion, the ISL-NE demonstrated excellent physicochemical properties, good tolerance, and enhanced ocular bioavailability. It could be a promising, safe, and effective treatment for CNV.

Development of Ciprofloxacin-Loaded Bilosomes In-Situ Gel for Ocular Delivery: Optimization, In-Vitro Characterization, Ex-Vivo Permeation, and Antimicrobial Study

Conventional eye drops are most commonly employed topically in the eye for the management of bacterial conjunctivitis. Eye drops have a low corneal residence time and 90−95% of the administered dose is eliminated from the eye by blinking and the nasolacrimal drainage system. This problem can be minimized by formulating a mucoadhesive ocular in-situ gel system that undergoes sol-gel transition upon stimulation by temperature, pH, and ions. The goal of this study was to develop ciprofloxacin (CIP) loaded bilosomes (BLO) in-situ gel for the improvement of therapeutic efficacy. The BLO was prepared by the thin-film hydration method and optimized by the Box−Behnken design. Cholesterol (CHO), surfactant (Span 60), and bile salt (sodium deoxycholate/SDC) were used as formulation factors. The vesicle size (nm) and entrapment efficiency (%) were selected as responses (dependent factors). The optimized CIP-BLO (CIP-BLO-opt) formulation displayed a vesicle size of 182.4 ± 9.2 nm, a polydispersity index of 0.274, a zeta potential of −34,461.51 mV, and an entrapment efficiency of 90.14 ± 1.24%. Both x-ray diffraction and differential scanning calorimetry spectra did not exhibit extensive peaks of CIP in CIP-BLO-opt, revealing that CIP is encapsulated in the BLO matrix. The CIP-BLO-opt formulation was successfully incorporated into an in-situ gel system using a gelling agent, i.e., Carbopol 934P and hydroxyl propyl methyl cellulose (HPMC K100 M). CIP-BLO-opt in-situ gel formulation (CIP-BLO-opt-IG3) was evaluated for gelling capacity, clarity, pH, viscosity, in-vitro CIP release, bio-adhesive, ex-vivo permeation, toxicity, and antimicrobial study. The CIP-BLO-opt-IG3 exhibited satisfactory gelling properties with a viscosity of 145.85 ± 9.48 cP in the gelling state. CIP-BLO-opt-IG3 displayed sustained CIP release (83.87 ± 5.24%) with Korsmeyer−Peppas kinetic as a best-fitted model (R2 = 0.9667). CIP-BLO-opt-IG3 exhibited a 1.16-fold than CIP-IG and a 2.08-fold higher permeability than pure CIP. CIP-BLO-opt-IG3 displayed a significantly greater bio-adhesion property (924.52 ± 12.37 dyne/cm2) than tear film. Further, CIP-BLO-opt-IG3 does not display any toxicity as confirmed by corneal hydration (76.15%), histology, and the HET-CAM test (zero scores). CIP-BLO-opt-IG3 shows significantly higher (p < 0.05) antimicrobial activity against P. aeruginosa and S. aureus than pure CIP. From all these findings, it could be concluded that CIP-BLO-opt-IG3 might be an effective strategy for the increment of corneal residence time and therapeutic activity of CIP.

Current Advances in Nano-Based and Polymeric Stimuli-Responsive Drug Delivery Targeting the Ocular Microenvironment: A Review and Envisaged Future Perspectives

Optimal vision remains one of the most essential elements of the sensory system continuously threatened by many ocular pathologies. Various pharmacological agents possess the potential to effectively treat these ophthalmic conditions; however, the use and efficacy of conventional ophthalmic formulations is hindered by ocular anatomical barriers. Recent novel designs of ophthalmic drug delivery systems (DDS) using nanotechnology show promising prospects, and ophthalmic formulations based on nanotechnology are currently being investigated due to their potential to bypass these barriers to ensure successful ocular drug delivery. More recently, stimuli-responsive nano drug carriers have gained more attention based on their great potential to effectively treat and alleviate many ocular diseases. The attraction is based on their biocompatibility and biodegradability, unique secondary conformations, varying functionalities, and, especially, the stimuli-enhanced therapeutic efficacy and reduced side effects. This review introduces the design and fabrication of stimuli-responsive nano drug carriers, including those that are responsive to endogenous stimuli, viz., pH, reduction, reactive oxygen species, adenosine triphosphate, and enzymes or exogenous stimuli such as light, magnetic field or temperature, which are biologically related or applicable in clinical settings. Furthermore, the paper discusses the applications and prospects of these stimuli-responsive nano drug carriers that are capable of overcoming the biological barriers of ocular disease alleviation and/or treatment for in vivo administration. There remains a great need to accelerate the development of stimuli-responsive nano drug carriers for clinical transition and applications in the treatment of ocular diseases and possible extrapolation to other topical applications such as ungual or otic drug delivery.

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.

Formulation and Evaluation of Nano Lipid Carrier-Based Ocular Gel System: Optimization to Antibacterial Activity

The present research work was designed to prepare Azithromycin (AM)-loaded nano lipid carriers (NLs) for ocular delivery. NLs were prepared by the emulsification–homogenization method and further optimized by the Box Behnken design. AM-NLs were optimized using the independent constraints of homogenization speed (A), surfactant concentration (B), and lipid concentration (C) to obtain optimal NLs (AM-NLop). The selected AM-NLop was further converted into a sol-gel system using a mucoadhesive polymer blend of sodium alginate and hydroxyl propyl methyl cellulose (AM-NLopIG). The sol-gel system was further characterized for drug release, permeation, hydration, irritation, histopathology, and antibacterial activity. The prepared NLs showed nano-metric size particles (154.7 ± 7.3 to 352.2 ± 15.8 nm) with high encapsulation efficiency (48.8 ± 1.1 to 80.9 ± 2.9%). AM-NLopIG showed a more prolonged drug release (98.6 ± 4.6% in 24 h) than the eye drop (99.4 ± 5.3% in 3 h). The ex vivo permeation result depicted AM-NLopIG, AM-IG, and eye drop. AM-NLopIG exhibited significant higher AM permeation (60.7 ± 4.1%) than AM-IG (33.46 ± 3.04%) and eye drop (23.3 ± 3.7%). The corneal hydration was found to be 76.45%, which is within the standard limit. The histopathology and HET-CAM results revealed that the prepared formulation is safe for ocular use. The antibacterial study revealed enhanced activity from the AM-NLopIG.

Development of a naringenin microemulsion as a prospective ophthalmic delivery system for the treatment of corneal neovascularization: in vitro and in vivo evaluation

Naringenin, a flavonoid, possesses antiangiogenic potential and inhibits corneal neovascularization (CNV); however, its therapeutic use is restricted due to poor solubility and limited bioavailability. In this study, we developed a naringenin microemulsion (NAR-ME) for inhibiting CNV. NAR-ME formulation was composed of triacetin (oil phase), Cremophor RH40 (CRH40), PEG400, and water, its droplet size was 13.22 ± 0.13 nm with a narrow size distribution (0.112 ± 0.0014). The results demonstrated that NAR-ME released higher and permeated more drug than NAR suspension (NAR-Susp) in in vitro drug release and ex vivo corneal permeation study. Human corneal epithelial cells (HCECs) toxicity study showed no toxicity with NAR-ME, which is consistent with the result of ocular irritation study. NAR-ME had high bioavailability 1.45-fold, 2.15-fold, and 1.35-fold higher than NAR-Susp in the cornea, conjunctiva, and aqueous humor, respectively. Moreover, NAR-ME (0.5% NAR) presented efficacy comparable to that of dexamethasone (0.025%) in the inhibition of CNV in mice CNV model induced by alkali burning, resulting from the attenuation of corneal vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP-14) expression. In conclusion, the optimized NAR-ME formulation demonstrated excellent physicochemical properties and good tolerance, enhanced ocular bioavailability and corneal permeability. This formulation is promising, safe, and effective for the treatment of CNV.

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.

Lipid-Based Nanocarriers as Topical Drug Delivery Systems for Intraocular Diseases

Effective drug delivery to intraocular tissues remains a great challenge due to complex anatomical and physiological barriers that selectively limit the entry of drugs into the eye. To overcome these challenges, frequent topical application and regular intravitreal injections are currently used to achieve the desired drug concentrations into the eye. However, the repetitive installation or recurrent injections may result in several side effects. Recent advancements in the field of nanoparticle-based drug delivery have demonstrated promising results for topical ophthalmic nanotherapies in the treatment of intraocular diseases. Studies have revealed that nanocarriers enhance the intraocular half-life and bioavailability of several therapies including proteins, peptides and genetic material. Amongst the array of nanoparticles available nowadays, lipid-based nanosystems have shown an increased efficiency and feasibility in topical formulations, making them an important target for constant and thorough research in both preclinical and clinical practice. In this review, we will cover the promising lipid-based nanocarriers used in topical ophthalmic formulations for intraocular drug delivery.