Positively charged polymeric nanoparticles improve ocular penetration of tacrolimus after topical administration

A SU6668 pure nanoparticle-based eyedrops: toward its high drug Accumulation and Long-time treatment for corneal neovascularization

Corneal neovascularization (CNV) is one of the common blinding factors worldwide, leading to reduced vision or even blindness. However, current treatments such as surgical intervention and anti-VEGF agent therapy still have some shortcomings or evoke some adverse effects. Recently, SU6668, an inhibitor targeting angiogenic tyrosine kinases, has demonstrated growth inhibition of neovascularization. But the hydrophobicity and low ocular bioavailability limit its application in cornea. Hereby, we proposed the preparation of SU6668 pure nanoparticles (NanoSU6668; size ~135 nm) using a super-stable pure-nanomedicine formulation technology (SPFT), which possessed uniform particle size and excellent aqueous dispersion at 1 mg/mL. Furthermore, mesenchymal stem cell membrane vesicle (MSCm) was coated on the surface of NanoSU6668, and then conjugated with TAT cell penetrating peptide, preparing multifunctional TAT-MSCm@NanoSU6668 (T-MNS). The T-MNS at a concentration of 200 µg/mL was treated for CNV via eye drops, and accumulated in blood vessels with a high targeting performance, resulting in elimination of blood vessels and recovery of cornea transparency after 4 days of treatment. Meanwhile, drug safety test confirmed that T-MNS did not cause any damage to cornea, retina and other eye tissues. In conclusion, the T-MNS eye drop had the potential to treat CNV effectively and safely in a low dosing frequency, which broke new ground for CNV theranostics.

Drug delivery methods based on nanotechnology for the treatment of eye diseases

One of the most difficult tasks among the numerous medication delivery methods is ocular drug delivery. Despite having effective medications for treating ocular illness, we have not yet managed to develop an appropriate drug delivery strategy with the fewest side effects. Nanotechnology has the potential to significantly address the drawbacks of current ocular delivery systems, such as their insufficient therapeutic effectiveness and unfavourable side effects from invasive surgery or systemic exposure. The objective of the current research is to highlight and update the most recent developments in nano-based technologies for the detection and treatment of ocular diseases. Even if more work has to be done, the advancements shown here might lead to brand-new, very practical ocular nanomedicines.

Tacrolimus-Loaded Cationic Nanoemulsion In-Situ Gel System: In-Vitro Characterization and Performance in a Dry-Eye Rabbit Model

Dry eye disease (DED) is a highly prevalent ocular surface disease that affects life quality and reduces productivity at work. The purpose of this study is to improve the efficacy of tacrolimus (FK506) in the treatment of DED using the special eye surface retention properties of cationic nanoemulsion (CNE) modified by thermosensitive in-situ gel (ISG) (CNE-ISG). The precorneal retention of CNE-ISG containing 0.05% FK506 (50 min) was longer than that of CNE containing 0.05% FK506 (25 min) and commercial suspension containing 0.1% FK506 (Talymus®) (10 min). Successfully modeled dry-eye rabbits were treated with 0.05% CNE-ISG (twice/day), 0.05% CNE and 0.1% suspension (Talymus®) (thrice/day). Schirmer's tear secretion test showed no significant difference between the CNE-ISG group and the healthy group after 5 days of treatment (p > 0.05). The results of a tear ferning test (TFT) showed that the tear-fern-like crystal branches in the CNE-ISG group returned to normal after 5 days of treatment. Histological analysis showed that the number of goblet cells in the CNE-ISG group significantly increased. HET-CAM stimulation test showed that the CNE-ISG group had no ocular irritation. The above results indicated that CNE-ISG might be a promising delivery system and as an effective dosage form was employed for FK506 in the treatment of DED.

Nanocarriers significantly augment the absorption of ocular-delivered drugs: A comparative meta-analysis study

This study presents a meta-analysis that compiles information collected from several studies aiming to prove, by evidence, that nanocarriers out-perform conventional formulations in augmenting the bioavailability of ocular topically administered drugs. Data was further categorized into two subgroups; polymeric-based nanocarriers versus their lipid-based counterparts, as well as, naturally-driven carriers versus synthetically-fabricated ones. After normalization, the pharmacokinetic factor, area under the curve (AUC), was denoted as the "effect" in the conducted study, and the corresponding Forest plots were obtained. Our meta-analysis study confirmed the absorption enhancement effect of loading drugs into nanocarriers as compared to conventional topical ocular dosage forms. Interestingly, no significant differences were recorded between the polymeric and lipidic nanocarriers included in the study, while naturally-driven nanoplatforms were proven superior to the synthetic alternatives.

Recent Advances of Ocular Drug Delivery Systems: Prominence of Ocular Implants for Chronic Eye Diseases

Chronic ocular diseases can seriously impact the eyes and could potentially result in blindness or serious vision loss. According to the most recent data from the WHO, there are more than 2 billion visually impaired people in the world. Therefore, it is pivotal to develop more sophisticated, long-acting drug delivery systems/devices to treat chronic eye conditions. This review covers several drug delivery nanocarriers that can control chronic eye disorders non-invasively. However, most of the developed nanocarriers are still in preclinical or clinical stages. Long-acting drug delivery systems, such as inserts and implants, constitute the majority of the clinically used methods for the treatment of chronic eye diseases due to their steady state release, persistent therapeutic activity, and ability to bypass most ocular barriers. However, implants are considered invasive drug delivery technologies, especially those that are nonbiodegradable. Furthermore, in vitro characterization approaches, although useful, are limited in mimicking or truly representing the in vivo environment. This review focuses on long-acting drug delivery systems (LADDS), particularly implantable drug delivery systems (IDDS), their formulation, methods of characterization, and clinical application for the treatment of eye diseases.

In-Situ Thermoresponsive Hydrogel Containing Resveratrol-Loaded Nanoparticles as a Localized Drug Delivery Platform for Dry Eye Disease

Dry eye disease (DED) is a dynamic and complex disease that can cause significant damage to the ocular surface and discomfort, compromising the patient's quality of life. Phytochemicals such as resveratrol have received increasing attention due to their ability to interfere with multiple pathways related to these diseases. However, the low bioavailability and the poor therapeutic response of resveratrol hinder its clinical applications. Cationic polymeric nanoparticles, in combination with in situ gelling polymers, could represent a promising strategy to prolong drug corneal residence time reducing the frequency of administration and increasing the therapeutic response. Eyedrop formulations, based on acetylated polyethyleneimine-modified polylactic-co-glicolyc acid- (PLGA-PEI) nanoparticles loaded with resveratrol (RSV-NPs) were dispersed into poloxamer 407 hydrogel and characterized in terms of pH, gelation time, rheological properties, in vitro drugs release, and biocompatibility. Moreover, the antioxidant and anti-inflammatory effects of RSV were assessed in vitro by mimicking a DED condition through the exposition of epithelial corneal cells to a hyperosmotic state. This formulation exhibited sustained release of RSV for up to 3 days, exerting potent antioxidant and anti-inflammatory effects on corneal epithelial cells. In addition, RSV reversed the mitochondrial dysfunction mediated by high osmotic pressure, leading to upregulated sirtuin-1 (SIRT1) expression, an essential regulator of mitochondrial function. These results suggest the potential of eyedrop formulation as a platform to overcome the rapid clearance of current solutions for treating various inflammation- and oxidative stress-related diseases such as DED.

Preparation and Characterization of Ion-Sensitive Brimonidine Tartrate In Situ Gel for Ocular Delivery

Brimonidine tartrate (BRT) is a highly selective α2 adrenergic receptor agonist as treatment for patients with open angle glaucoma and high intraocular pressure. The objective of this study was to formulate an ophthalmic ion-sensitive in situ gel (ISG) of BRT to increase the retention time of the drug and its bioavailability. The optimum formulation of 2 mg/mL BRT-ISG was obtained with 0.45% gellan gum as the gel matrix. In vitro release results showed that the water-soluble drug bromonidine tartrate in ocular in situ gels exhibited a high burst effect and fast release in solution. The results of dialysis membrane permeation showed that there was a significant difference between the commercially available and BRT-ISG groups after 45 min. The results of the pre-corneal retention study indicated that gellan gum can effectively prolong ocular surface retention. Preliminary stability results showed that it should be stored in a cool and dark place, and the formulation under long-term preservation can be basically stable. The pharmacokinetic study of the BRT-ISG in the anterior chamber of the rabbit eye was studied by microdialysis technique, and microdialysis samples were analyzed by LC-MS/MS. The pharmacokinetic study showed that the BRT-ISG reached Cmax (8.16 mg/L) at 93 min after administration, which was 2.7 times that of the BRT eye drops, and the AUC(0-t) (1397.08 mg·min/L) was 3.4 times that of the BRT eye drops. The optimal prescription can prolong the retention time of BRT in front of the cornea and significantly improve the bioavailability of BRT in the eye. Combined with the results of in vitro release, permeation and pre-corneal retention studies, the improvement of BRT-ISG bioavailability in rabbit eyes was found to be mainly due to the retention effect after the mixture of ISG and tears.

Functional Peptide-Loaded Gelatin Nanoparticles as Eyedrops for Cornea Neovascularization Treatment

Background

Corneal neovascularization (NV) is a process of abnormal vessel growth into the transparent cornea from the limbus and can disturb the light passing through the cornea, resulting in vision loss or even blindness. The use of nanomedicine as an effective therapeutic formulation in ophthalmology has led to higher drug bioavailability and a slow drug release rate. In this research, we designed and explored the feasibility of a new nanomedicine, gp91 ds-tat (gp91) peptide-encapsulated gelatin nanoparticles (GNP-gp91), for inhibiting corneal angiogenesis.

Methods

GNP-gp91 were prepared by a two-step desolvation method. The characterization and cytocompatibility of GNP-gp91 were analyzed. The inhibition effect of GNP-gp91 on HUVEC cell migration and tube formation was observed by an inverted microscope. The drug retention test in mouse cornea was observed by in vivo imaging system, fluorescence microscope, and DAPI/TAMRA staining. Finally, the therapeutic efficacy and evaluation of neovascularization-related factors were conducted through the in vivo corneal NV mice model via topical delivery.

Results

The prepared GNP-gp91 had a nano-scale diameter (550.6 nm) with positive charge (21.7 mV) slow-release behavior (25%, 240hr). In vitro test revealed that GNP-gp91 enhanced the inhibition of cell migration and tube formation capacity via higher internalization of HUVEC. Topical administration (eyedrops) of the GNP-gp91 significantly prolongs the retention time (46%, 20 min) in the mouse cornea. In chemically burned corneal neovascularization models, corneal vessel area with a significant reduction in GNP-gp91 group (7.89%) was revealed when compared with PBS (33.99%) and gp91 (19.67%) treated groups via every two days dosing. Moreover, GNP-gp91 significantly reduced the concentration of Nox2, VEGF and MMP9 in NV's cornea.

Conclusion

The nanomedicine, GNP-gp91, was successfully synthesized for ophthalmological application. These data suggest that GNP-gp91 contained eyedrops that not only have a longer retention time on the cornea but also can treat mice corneal NV effectively delivered in a low dosing frequency, GNP-gp91 eyedrops provides an alternative strategy for clinical ocular disease treatment in the culture.

Thymol-Loaded Eudragit RS30D Cationic Nanoparticles-Based Hydrogels for Topical Application in Wounds: In Vitro and In Vivo Evaluation

Natural medicines formulated using nanotechnology-based systems are a rich source of new wound-treating therapeutics. This study aims to develop thymol-loaded cationic polymeric nanoparticles (CPNPs) to enhance the skin retention and wound healing efficacy of thymol. The developed materials exhibited entrapment efficiencies of 56.58 to 68.97%, particle sizes of 36.30 to 99.41 nm, and positively charged zeta potential. In Vitro sustained release of thymol up to 24 h was achieved. Selected thymol CPNPs (F5 and C2) were mixed with methylcellulose to form hydrogels (GF5 and GC2). An In Vivo skin-retention study revealed that GF5 and GC2 showed 3.3- and 3.6-fold higher retention than free thymol, respectively. An In Vitro scratch-wound healing assay revealed a significant acceleration in wound closure at 24 h by 58.09% (GF5) and 57.45% (GC2). The potential for free thymol hydrogel, GF5, and GC2 to combat MRSA in a murine skin model was evaluated. The bacterial counts, recovered from skin lesions and the spleen, were assessed. Although a significant reduction in the bacterial counts recovered from the skin lesions was shown by all three formulations, only GF5 and GC2 were able to reduce the bacterial dissemination to the spleen. Thus, our study suggests that Eudragit RS30D nanoparticles-based hydrogels are a potential delivery system for enhancing thymol skin retention and wound healing activity.

Recent achievements in nano-based technologies for ocular disease diagnosis and treatment, review and update

Ocular drug delivery is one of the most challenging endeavors among the various available drug delivery systems. Despite having suitable drugs for the treatment of ophthalmic disease, we have not yet succeeded in achieving a proper drug delivery approach with the least adverse effects. Nanotechnology offers great opportunities to overwhelm the restrictions of common ocular delivery systems, including low therapeutic effects and adverse effects because of invasive surgery or systemic exposure. The present review is dedicated to highlighting and updating the recent achievements of nano-based technologies for ocular disease diagnosis and treatment. While further effort remains, the progress illustrated here might pave the way to new and very useful ocular nanomedicines.

Preparation of a novel tacrolimus ion sensitive ocular in situ gel and in vivo evaluation of curative effect of immune conjunctivitis

BACKGROUND

The aim of this study was to formulate a novel TAC preparation into an in situ gel for ocular drug delivery, in order to prolong the residence time on mucosal surfaces and increase patient compliance.

METHODS

The optimal formulation was characterized by surface morphology, gelling capacity, viscosity, stability and in vitro release. In vivo studies were also conducted to evaluate the precorneal retention and pharmacodynamic results.

RESULTS

In this study, the TAC in situ gel can be prepared by a simple solvent stirring method, and the optimized formulation exhibited good stability within 3 months. During storage, the initial viscosity of the formula had little change. The results of viscosity measurement showed that TAC in situ gel was typical of pseudo plastic systems and exhibited a marked increase in viscosity stimulated with STF. In vitro and in vivo studies illustrated that TAC in situ gel administration facilitated the retention and sustained release of TAC.

CONCLUSIONS

TAC combined with in situ gelling agents demonstrates an efficient topical drug delivery platform.

Structure-Based Varieties of Polymeric Nanocarriers and Influences of Their Physicochemical Properties on Drug Delivery Profiles

Carriers are equally important as drugs. They can substantially improve bioavailability of cargos and safeguard healthy cells from toxic effects of certain therapeutics. Recently, polymeric nanocarriers (PNCs) have achieved significant success in delivering drugs not only to cells but also to subcellular organelles. Variety of natural sources, availability of different synthetic routes, versatile molecular architectures, exploitable physicochemical properties, biocompatibility, and biodegradability have presented polymers as one of the most desired materials for nanocarrier design. Recent innovative concepts and advances in PNC-associated nanotechnology are providing unprecedented opportunities to engineer nanocarriers and their functions. The efficiency of therapeutic loading has got considerably increased. Structural design-based varieties of PNCs are widely employed for the delivery of small therapeutic molecules to genes, and proteins. PNCs have gained ever-increasing attention and certainly paves the way to develop advanced nanomedicines. This article presents a comprehensive investigation of structural design-based varieties of PNCs and the influences of their physicochemical properties on drug delivery profiles with perspectives highlighting the inevitability of incorporating both the multi-stimuli-responsive and multi-drug delivery properties in a single carrier to design intelligent PNCs as new and emerging research directions in this rapidly developing area.

Targeted drug delivery vehicles mediated by nanocarriers and aptamers for posterior eye disease therapeutics: barriers, recent advances and potential opportunities

Nanomedicine and aptamer have excellent potential in giving play to passive and active targeting respectively, which are considered to be effective strategies in the retro-ocular drug delivery system. The presence of closely adjoined tissue structures in the eye makes it difficult to administer the drug in the posterior segment of the eye. The application of nanomedicine could represent a new avenue for the treatment, since it could improve penetration, achieve targeted release, and improve bioavailability. Additionally, a novel type of targeted molecule aptamer with identical objective was proposed. As an emerging molecule, aptamer shows the advantages of penetration, non-toxicity, and high biocompatibility, which make it suitable for ocular drug administration. The purpose of this paper is to summarize the recent studies on the effectiveness of nanoparticles as a drug delivery to the posterior segment of the eye. This paper also creatively looks forward to the possibility of the combined application of nanocarriers and aptamers as a new method of targeted drug delivery system in the field of post-ophthalmic therapy.

Nanotechnology for Topical Drug Delivery to the Anterior Segment of the Eye

Topical drug delivery is one of the most challenging aspects of eye therapy. Eye drops are the most prevalent drug form, especially for widely distributed anterior segment eye diseases (cataracts, glaucoma, dry eye syndrome, inflammatory diseases, etc.), because they are convenient and easy to apply by patients. However, conventional drug formulations are usually characterized by short retention time in the tear film, insufficient contact with epithelium, fast elimination, and difficulties in overcoming ocular tissue barriers. Not more than 5% of the total drug dose administered in eye drops reaches the interior ocular tissues. To overcome the ocular drug delivery barriers and improve drug bioavailability, various conventional and novel drug delivery systems have been developed. Among these, nanosize carriers are the most attractive. The review is focused on the different drug carriers, such as synthetic and natural polymers, as well as inorganic carriers, with special attention to nanoparticles and nanomicelles. Studies in vitro and in vivo have demonstrated that new formulations could help to improve the bioavailability of the drugs, provide sustained drug release, enhance and prolong their therapeutic action. Promising results were obtained with drug-loaded nanoparticles included in in situ gel.

Formulation development, optimization, and in vitro assessment of thermoresponsive ophthalmic pluronic F127-chitosan in situ tacrolimus gel

To overcome problems associated with topical delivery of tacrolimus (TCS), a thermoresponsive in situ gel system containing pluronic F127 (PL), and chitosan (CS) was developed, to enhance the precorneal retention, and to sustain the release of the drug. The PL-CS in situ gel was optimized using a 2-factor-3-level central composite experimental design by selecting the concentration of PL and CS as independent variables while gelation time, gelation temperature, and spreadability as dependent variables. The optimized formulation was developed using 22.5 g PL and 0.3 g CS, gels at 33.6 °C, in 22.93 s, and showed the spreadability of 6.2 cm. In vitro studies conducted for the optimized gel revealed the sustained release of TCS (81.73% in 4 h) and improved corneal permeation (74.13% in 4 h), compared with TCS solution. The mechanism of release of TCS followed the Higuchi model with Fickian diffusion transport. Further, histopathology and HET-CAM studies revealed that the developed gel was non-irritating and safe for ocular administration.