Lipid Nanocarrier: an Efficient Approach Towards Ocular Delivery of Hydrophilic Drug (Valacyclovir)

Clinical strategies to prevent recurrence of Herpes simplex and Herpes zoster following ocular surgery: A comprehensive review with practical guidelines

Recurrences of herpetic infections following intraocular surgeries pose a threat to optimal surgical outcomes. The high prevalence of herpetic diseases require ophthalmologists to be familiar with the special measures in the surgery of these patients. A thorough preoperative assessment and meticulous postoperative surveillance should be tailored for each patient, depending on the surgery and the risk of virus reactivation. We compile the relevant evidence in the literature and provide a comprehensive review of the preoperative assessment and postoperative diagnostic clues and management of the herpetic infections following different types of intraocular surgeries, including cataract surgery, keratoplasty, corneal crosslinking, glaucoma, and refractive surgeries.

Enhanced Anti-Herpetic Activity of Valacyclovir Loaded in Sulfobutyl-ether-β-cyclodextrin-decorated Chitosan Nanodroplets

Valacyclovir (VACV) was developed as a prodrug of the most common anti-herpetic drug Acyclovir (ACV), aiming to enhance its bioavailability. Nevertheless, prolonged VACV oral treatment may lead to the development of important side effects. Nanotechnology-based formulations for vaginal administration represent a promising approach to increase the concentration of the drug at the site of infection, limiting systemic drug exposure and reducing systemic toxicity. In this study, VACV-loaded nanodroplet (ND) formulations, optimized for vaginal delivery, were designed. Cell-based assays were then carried out to evaluate the antiviral activity of VACV loaded in the ND system. The chitosan-shelled ND exhibited an average diameter of about 400 nm and a VACV encapsulation efficiency of approximately 91% and was characterized by a prolonged and sustained release of VACV. Moreover, a modification of chitosan shell with an anionic cyclodextrin, sulfobutyl ether β-cyclodextrin (SBEβCD), as a physical cross-linker, increased the stability and mucoadhesion capability of the nanosystem. Biological experiments showed that SBEβCD-chitosan NDs enhanced VACV antiviral activity against the herpes simplex viruses type 1 and 2, most likely due to the long-term controlled release of VACV loaded in the ND and an improved delivery of the drug in sub-cellular compartments.

Hyaluronic Acid-Coated Chitosan/Gelatin Nanoparticles as a New Strategy for Topical Delivery of Metformin in Melanoma

Metformin is a multipotential compound for treating diabetes II and controlling hormonal acne and skin cancer. This study was designed to enhance metformin skin penetration in melanoma using nanoparticles containing biocompatible polymers. Formulations with various concentrations of chitosan, hyaluronic acid, and sodium tripolyphosphate were fabricated using an ionic gelation technique tailored by the Box-Behnken design. The optimal formulation was selected based on the smallest particle size and the highest entrapment efficiency (EE%) and used in ex vivo skin penetration study. In vitro antiproliferation activity and apoptotic effects of formulations were evaluated using MTT and flow cytometric assays, respectively. The optimized formulation had an average size, zeta potential, EE%, and polydispersity index of 329 ± 6.30 nm, 21.94 ± 0.05 mV, 64.71 ± 6.12%, and 0.272 ± 0.010, respectively. The release profile of the optimized formulation displayed a biphasic trend, characterized by an early burst release, continued by a slow and sustained release compared to free metformin. The ex vivo skin absorption exhibited 1142.5 ± 156.3 μg/cm² of metformin deposited in the skin layers for the optimized formulation compared to 603.2 ± 93.1 μg/cm² for the free metformin. Differential scanning calorimetry confirmed the deformation of the drug from the crystal structure to an amorphous state. The attenuated total reflection Fourier transform infrared results approved no chemical interaction between the drug and other ingredients of the formulations. According to the MTT assay, metformin in nanoformulation exhibited a higher cytotoxic effect against melanoma cancer cells than free metformin (IC₅₀: 3.94 ± 0.57 mM vs. 7.63 ± 0.26 mM, respectively, P < 0.001). The results proved that the optimized formulation of metformin could efficiently decrease cell proliferation by promoting apoptosis, thus providing a promising strategy for melanoma therapy.

Antiviral role of nanomaterials: a material scientist's perspective

The present world continues to face unprecedented challenges caused by the COVID-19 pandemic. Collaboration between researchers of multiple disciplines is the need of the hour. There is a need to develop antiviral agents capable of inhibiting viruses and tailoring existing antiviral drugs for efficient delivery to prevent a surge in deaths caused by viruses globally. Biocompatible systems have been designed using nanotechnological principles which showed appreciable results against a wide range of viruses. Many nanoparticles can act as antiviral therapeutic agents if synthesized by the correct approach. Moreover, nanoparticles can act as carriers of antiviral drugs while overcoming their inherent drawbacks such as low solubility, poor bioavailability, uncontrolled release, and side effects. This review highlights the potential of nanomaterials in antiviral applications by discussing various studies and their results regarding antiviral potential of nanoparticles while also suggesting future directions to researchers.

Lipid Nanoparticles as a Promising Drug Delivery Carrier for Topical Ocular Therapy-An Overview on Recent Advances

Due to complicated anatomical and physical properties, targeted drug delivery to ocular tissues continues to be a key challenge for formulation scientists. Various attempts are currently being made to improve the in vivo performance of therapeutic molecules by encapsulating them in various nanocarrier systems or devices and administering them via invasive/non-invasive or minimally invasive drug administration methods. Biocompatible and biodegradable lipid nanoparticles have emerged as a potential alternative to conventional ocular drug delivery systems to overcome various ocular barriers. Lipid-based nanocarrier systems led to major technological advancements and therapeutic advantages during the last few decades of ocular therapy, such as high precorneal residence time, sustained drug release profile, minimum dosing frequency, decreased drug toxicity, targeted site delivery, and, therefore, an improvement in ocular bioavailability. In addition, such formulations can be given as fine dispersion in patient-friendly droppable preparation without causing blurred vision and ocular sensitivity reactions. The unique advantages of lipid nanoparticles, namely, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, and liposomes in intraocular targeted administration of various therapeutic drugs are extensively discussed. Ongoing and completed clinical trials of various liposome-based formulations and various characterization techniques designed for nanoemulsion in ocular delivery are tabulated. This review also describes diverse solid lipid nanoparticle preparation methods, procedures, advantages, and limitations. Functionalization approaches to overcome the drawbacks of lipid nanoparticles, as well as the exploration of new functional additives with the potential to improve the penetration of macromolecular pharmaceuticals, would quickly progress the challenging field of ocular drug delivery systems.

Formulation and Pathohistological Study of Mizolastine-Solid Lipid Nanoparticles-Loaded Ocular Hydrogels

Background

Mizolastine (MZL) is a dual-action nonsedating topical antihistamine anti-inflammatory agent that is used to relieve allergic conditions, such as rhinitis and conjunctivitis. Solid lipid nanoparticles (SLNs) are advanced delivery system in ophthalmology, with the merits of increasing the corneal drug absorption and hence improved bioavailability with the objective of ocular drug targeting.

Methods

First, MZL was formulated as MZL-SLNs by hot homogenization/ultrasonication adopting a 3² full factorial design. Solid-state characterization, in vitro release, and stability studies have been performed. Then, the optimized MZL-SLNs formula has been incorporated into ocular hydrogels using 1.5% w/v Na alginate and 5% w/v polyvinylpyrrolidone K₉₀. The gels were evaluated via in vitro release as well as in vivo studies by applying allergic conjunctivitis congestion in a rabbit-eye model.

Results

The optimized formula (F4) was characterized by the highest entrapment efficiency (86.5±1.47%), the smallest mean particle size (202.3±13.59 nm), and reasonable zeta potential (−22.03±3.65 mV). Solid-state characterization of the encapsulation of MZL in SLNs was undertaken. In vitro results showed a sustained release profile from MZL-SLNs up to 30 hours with a non-Fickian Higuchi kinetic model. Stability studies confirmed immutability of freeze-dried MZL-SLNs (F4) upon storage for 6 months. Finally, hydrogel formulations containing MZL-SLNs, proved ocular congestion disappearance with completely repaired conjunctiva after 24 hours. Moreover, pretreatment with MZL-SLNs–loaded hydrogel imparted markedly decreased TNF-α and VEGF-expression levels in rabbits conjunctivae compared with post-treatment with the same formula.

Conclusion

MZL-SLNs could be considered a promising stable sustained-release nanoparticulate system for preparing ocular hydrogel as effective antiallergy ocular delivery systems.

Sorafenib Repurposing for Ophthalmic Delivery by Lipid Nanoparticles: A Preliminary Study

Uveal melanoma is the second most common melanoma and the most common intraocular malignant tumour of the eye. Among various treatments currently studied, Sorafenib was also proposed as a promising drug, often administered with other compounds in order to avoid resistance mechanisms. Despite its promising cellular activities, the use of Sorafenib by oral administration is limited by its severe side effects and the difficulty to reach the target. The encapsulation into drug delivery systems represents an interesting strategy to overcome these limits. In this study, different lipid nanoparticulate formulations were prepared and compared in order to select the most suitable for the encapsulation of Sorafenib. In particular, two solid lipids (Softisan or Suppocire) at different concentrations were used to produce solid lipid nanoparticles, demonstrating that higher amounts were able to achieve smaller particle sizes, higher homogeneity, and longer physical stability. The selected formulations, which demonstrated to be biocompatible on Statens Seruminstitut Rabbit Cornea cells, were modified to improve their mucoadhesion, evaluating the effect of two monovalent cationic lipids with two lipophilic chains. Sorafenib encapsulation allowed obtaining a sustained and prolonged drug release, thus confirming the potential use of the developed strategy to topically administer Sorafenib in the treatment of uveal melanoma.

Advanced Material Against Human (Including Covid-19) and Plant Viruses: Nanoparticles As a Feasible Strategy

The SARS-CoV-2 virus outbreak revealed that these nano-pathogens have the ability to rapidly change lives. Undoubtedly, SARS-CoV-2 as well as other viruses can cause important global impacts, affecting public health, as well as, socioeconomic development. But viruses are not only a public health concern, they are also a problem in agriculture. The current treatments are often ineffective, are prone to develop resistance, or cause considerable adverse side effects. The use of nanotechnology has played an important role to combat viral diseases. In this review three main aspects are in focus: first, the potential use of nanoparticles as carriers for drug delivery. Second, its use for treatments of some human viral diseases, and third, its application as antivirals in plants. With these three themes, the aim is to give to readers an overview of the progress in this promising area of biotechnology during the 2017-2020 period, and to provide a glance at how tangible is the effectiveness of nanotechnology against viruses. Future prospects are also discussed. It is hoped that this review can be a contribution to general knowledge for both specialized and non-specialized readers, allowing a better knowledge of this interesting topic.

Advancement on Sustained Antiviral Ocular Drug Delivery for Herpes Simplex Virus Keratitis: Recent Update on Potential Investigation

The eyes are the window to the world and the key to communication, but they are vulnerable to multitudes of ailments. More serious than is thought, corneal infection by herpes simplex viruses (HSVs) is a prevalent yet silent cause of blindness in both the paediatric and adult population, especially if immunodeficient. Globally, there are 1.5 million new cases and forty thousand visual impairment cases reported yearly. The Herpetic Eye Disease Study recommends topical antiviral as the front-line therapy for HSV keratitis. Ironically, topical eye solutions undergo rapid nasolacrimal clearance, which necessitates oral drugs but there is a catch of systemic toxicity. The hurdle of antiviral penetration to reach an effective concentration is further complicated by drugs’ poor permeability and complex layers of ocular barriers. In this current review, novel delivery approaches for ocular herpetic infection, including nanocarriers, prodrugs, and peptides are widely investigated, with special focus on advantages, challenges, and recent updates on in situ gelling systems of ocular HSV infections. In general congruence, the novel drug delivery systems play a vital role in prolonging the ocular drug residence time to achieve controlled release of therapeutic agents at the application site, thus allowing superior ocular bioavailability yet fewer systemic side effects. Moreover, in situ gel functions synergistically with nanocarriers, prodrugs, and peptides. The findings support that novel drug delivery systems have potential in ophthalmic drug delivery of antiviral agents, and improve patient convenience when prolonged and chronic topical ocular deliveries are intended.

Imprinted Contact Lenses for Ocular Administration of Antiviral Drugs

A variety of ocular diseases are caused by viruses, and most treatments rely on the use of systemic formulations and eye drops. The efficient ocular barriers that oppose antiviral drug penetration have prompted the development of improved topical delivery platforms. The aim was to design hydrogel contact lenses endowed with an affinity for acyclovir (ACV) and its prodrug valacyclovir (VACV), first-choice drugs against herpes simplex virus (HSV) ocular keratitis, and that can sustain the release of therapeutic doses during daily wearing. Functional monomers suitable for interaction with these drugs were screened using computational modeling. Imprinted and non-imprinted hydrogels were prepared with various contents in the functional monomer methacrylic acid (MAA) and characterized in terms of swelling, transmittance, mechanical properties, and ocular compatibility (hen’s egg test on chorioallantoic membrane (HET-CAM) assay). The values were in the range typical of soft contact lenses. Compared to ACV, the capability to load VACV was remarkably higher due to stronger electrostatic interactions with MAA. The advantages of the imprinting technology were evidenced for VACV. Stability of VACV loading solution/hydrogels under steam heat sterilization and subsequent drug release was investigated. Permeability studies through bovine and porcine cornea and sclera of the drug released from the hydrogels revealed that VACV accumulates in the cornea and can easily cross the sclera, which may facilitate the treatment of both anterior and posterior eye segments diseases.

PEGylated microemulsion for dexamethasone delivery to posterior segment of eye

Dexamethasone (Dex) is one of the most commonly used anti-vascular endothelial growth factor (anti-VEGF) drugs being used in ocular diseases whether it is associated with anterior segment or posterior segment. For diseases of posterior segment of eye, Dex is delivered as intravitreal implant but the route used for the same is very invasive and poses several hazards on long term use. Thus, topical formulation with ability to outreach retina from ocular surface was intended. Thus, polyethylene glycolylated (PEGylated) microemulsion (ME) was attempted as it can cross the membranous barrier of eye (cornea, conjunctiva, and sclera) and remain afloat in fluidic barrier (aqueous humor, choroid, etc.) as well. Present investigation involved development of Dex-loaded PEGylated ME which was stable, non-toxic to ocular surface, capable to cross cornea and enhanced residence as well as availability of loaded drug in retina. The developed PEGylated ME had physicochemical properties like size (15.98 ± 3.05 nm), polydispersity index (0.25 ± 0.04), zeta potential (-0.04 ± 0.47 mV), percentage transmittance (99.84 ± 1.17%), and drug content (99.32 ± 3.21%). It showed sustained Dex release in in vitro conditions. It also displayed efficiency in enhancing retention of drugs in retina in in vivo pharmacokinetic study on Sprague-Dawley rats. PEGylated ME can retain the drug in retina of rats longer than simple eye drop solution via topical ocular route.

Synthesis and Characterization of Valacyclovir HCl Hybrid Solid Lipid Nanoparticles by Using Natural Oils

BACKGROUND

The Jojoba Simmondsia Chinensis oil is used as one of the main ingredients which has an antioxidant, moisturizing and stabilizing activity. Likewise, grape seed (Vitis vinifera) oil is also used in this preparation which also has some remarkable medicinal properties such as antioxidant, astringent and is also used as a moisturizer. The Valacyclovir Solid Lipid Nanoparticles (SLN) are prepared in combination.

OBJECTIVE

The prime objective of the study was to prepare a nanodispersion with good stability indicating zeta potential. The formulations were prepared by varying concentrations of jojoba oil and grape seed oil which form the hybrid nanoparticles with the drug.

METHODS

The high-pressure hot-homogenization technique was used to prepare the nanoparticles. The prepared nanoparticles were subjected to characterization analysis such as Mean particle size, Zaverage, and Zeta potential by using Dynamic Light Scattering (DLS) and Photon Correlation Spectroscopy (PCS). The best formulation was subjected to Transmission Electron Microscopy (TEM) technique for surface morphology and other characterizations. The crystalline pattern of the drug alone, drug-loaded nanoparticles and nanoparticles without the drug was studied by XRD. The drug excipients compatibility studies were performed by using Fourier-Transform Infrared Spectroscopy (FTIR) Differential Scanning Calorimetry and (DSC). The other factors such as in vitro drug release, and % drug entrapment efficiency were studied by using suitable methods.

RESULTS

The results demonstrated that the particles are in nano range with good stability with appreciable Zeta potential (-48.2±mV). The selected formulations were analyzed for MPS which demonstrated the value of 306.7±183.4 and 416.5±289.3. The best formulation VNP5 demonstrated the Bellshaped curve and confirmed the uniform distribution.

CONCLUSION

Based on the patents, it was demonstrated that valacyclovir is widely used in the treatment and prophylaxis of viral infections in human, particularly infections caused by the herpes group of viruses. Valacyclovir is an effective drug for the treatment of cold sores.

Recent advances in topical nano drug-delivery systems for the anterior ocular segment

Over the past decade, there has been a rise in the number of clinical cases of moderate to severe anterior segment ocular diseases. Conventional topical ophthalmic formulations have several limitations - to address which, novel drug-delivery systems are needed. Additionally, formidable physiological barriers limit ocular bioavailability through the topical route of application. During the last decade, various nano-scaled ocular drug-delivery strategies have been reported. Some of these exploratory, topical, noninvasive approaches have shown promise in improving penetration into the anterior segment tissues of the eye. In this article, we review the available literature with respect to the safety, efficiency and effectiveness of these nano systems.

Topical gel of Metformin solid lipid nanoparticles: A hopeful promise as a dermal delivery system

The aim of the present study was to enhance the skin delivery of metformin by making solid lipid nanoparticles containing metformin using the ultra-sonication method. To achieve the optimum skin delivery for metformin, the effects of the ratio of two surfactants (Tween:Span) on nanoparticles properties and their performance were investigated. Photon correlation spectroscopy, scanning electron microscopy (SEM), Powder X-ray Diffractometer (PXRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to characterize the solid state of metformin in solid lipid nanoparticles. Generally, the particle size of nanoparticles decreased by the addition of co-emulsifier (Span®60). Results showed that all formulations made by binary mixtures of surfactants had low particle size, low Polydispersity index and high zeta potential. It was interesting to note that the smallest nanoparticles (203.8 ± 15.356) was obtained when the HLB of the binary surfactants (HLB of 11.67) was closer to the HLB of beeswax (HLB of 12) used in the preparation of SLN. It was also found that by decreasing the HLB of the system from 14.9 to 10.06 the zeta potential of SLNs increased from -0.651 ± 0.315 to -6.18 ± 0.438 mV. But, a further reduction in the HLB from 10.06 to 8.45 caused a reduction in the zeta potential from -6.18 to -3.596 ± 0.255. Results showed that the highest entrapment efficiency of 45.98 ± 9.20% was obtained for formulation with larger particle size and with the highest HLB value (HLB 14.9). DSC study showed that metformin in SLN is in an amorphous form. FT-IR spectra of Met-SLN showed that the prominent functional groups existed in the formulations which could be an indication of good entrapment of metformin in a lipid matrix. FT-IR results also ruled out any chemical interaction between the drug and the excipients. The amounts of metformin detected in the skin layers and the receptor chamber at all sampling times were higher for nanogel compared to metformin gel. This is an indication of a better performance of Metformin nanogel ex-vivo and could be developed further for clinical studies.

Novel Random Triblock Copolymers for Sustained Delivery of Macromolecules for the Treatment of Ocular Diseases

The objective of this study is to design, develop, and synthesize novel random triblock (RTB) copolymers for sustained delivery of macromolecules. RTB copolymers have not been utilized for the delivery of macromolecules for ocular diseases. RTB copolymers comprising of polyethylene glycol, glycolide, and ɛ-caprolactone blocks were synthesized and assessed for their molecular weights and purity using ¹H-NMR spectroscopy, gel permeation chromatography, FTIR (functionality), and XRD (crystallinity). No toxicity was observed when ocular cell lines were treated with RTB copolymers. These materials were applied for encapsulation of peptides and proteins (catalase, IgG, BSA, IgG Fab fragment, lysozyme, insulin, and octreotide) in nanoparticles. Particle size ranged from 202.41 ± 2.45 to 300.1 ± 3.11 nm depending on the molecular size and geometry of proteins/peptides. Polydispersity indices were between 0.26 ± 0.02 and 0.46 ± 0.07 respectively. Percentage entrapment efficiency and drug loading ranged from 83.44 ± 2.24 to 45.35 ± 5.53 and 21.56 ± 0.46 to 13.08 ± 1.35 respectively depending on molecular weights of peptides or proteins. A sustained in vitro release of macromolecule was observed over 3-month period. These results suggest that RTB copolymers may be suitable for sustained delivery systems for various macromolecules for different diseases including ocular diseases.

Curcumin-loaded Nanostructured Lipid Carriers for Ocular Drug Delivery: Design Optimization and Characterization

The current study sought to formulate, optimize, and evaluate curcumin-loaded Nanostructured Lipid Carriers (NLCs) for their in vitro and ex vivo characteristics. NLCs, prepared using hot-melt emulsification and ultrasonication techniques, were optimized using a Central Composite Design (CCD) and evaluated for their in vitro physicochemical characteristics. Their stability over a 3 month period and transcorneal permeation across excised rabbit corneas (ex vivo) were assessed for the optimized NLCs. The optimized NLC, with a particle size of 66.8 ± 2 nm, polydispersity index of 0.17±0.05, entrapment efficiency of 96 ± 1.6%, and drug loading of 3.1 ± 0.05% w/w, was chosen using CCD. The optimized NLCs showed optimum ex vivo stability at 4°C for the study period and demonstrated a significant increase in curcumin permeation (~2.5-fold) across the rabbit cornea in comparison to the control. Overall, these studies indicated the successful development of NLCs using the design of experiment approach; the formulation enhanced curcumin permeation across excised corneas and did not show any harmful side effects.

Novel nanosystems for the treatment of ocular inflammation: Current paradigms and future research directions

Ocular discomforts involve anterior/posterior-segment diseases, symptomatic distress and associated inflammations and severe retinal disorders. Conventionally, the formulations such as eye drops, eye solutions, eye ointments and lotions, etc. were used as modalities to attain relief from such ocular discomforts. However, eye allows limited access to these traditional formulations due to its unique anatomical structure and dynamic ocular environment and therefore calls for improvement in disease intervention. To address these challenges, development of nanotechnology based nanomedicines and novel nanosystems (liposomes, cubosomes, polymeric and lipidic nanoparticles, nanoemulsions, spanlastics and nano micelles) are currently in progress (some of them are already marketed such as Eye-logic liposomal eye spray@Naturalife, Ireland). Today, it is one of the central concept in designing more accessible formulations for deeper segments of the eyes. These nanosystems has largely enabled the availability of medicaments at required site in a required concentration without inversely affecting the eye tissues; and therefore, attaining the excessive considerations from the formulation scientists and pharmacologists worldwide. The entrapment of drugs, genes, and proteins inside these novel systems is the basis that works at the bio-molecular level bestows greater potential to eradicate disease causatives. In this review, we highlighted the recent attempts of nanotechnology-based systems for treating and managing various ocular ailments. The progress described herein may pave the way to new, highly effective and vital ocular nanosystems.