A novel ion-exchange carrier based upon liposome-encapsulated montmorillonite for ophthalmic delivery of betaxolol hydrochloride

Liposomal topical drug administration surpasses alternative methods in glaucoma therapeutics: a novel paradigm for enhanced treatment

OBJECTIVES

Glaucoma is a leading cause of permanent blindness. Despite therapeutic advancements, glaucoma management remains challenging due to limitations of conventional drug delivery, primarily topical eye drops, resulting in suboptimal outcomes and a global surge in cases. To address these issues, liposomal drug delivery has emerged as a promising approach.

KEY FINDINGS

This review explores the potential of liposomal-based medications, with a particular focus on topical administration as a superior alternative to enhance therapeutic efficacy and improve patient compliance compared to existing treatments. This writing delves into the therapeutic prospects of liposomal formulations across different administration routes, as evidenced by ongoing clinical trials. Additionally, critical aspects of liposomal production and market strategies are discussed herein.

SUMMARY

By overcoming ocular barriers and optimizing drug delivery, liposomal topical administration holds the key to significantly improving glaucoma treatment outcomes.

Montmorillonite: An advanced material with diverse pharmaceutical and medicinal applications

Montmorillonite (MMT) clay is composed of naturally layered silicate. The clays were more popular in the pharmaceutical and other various fields due to their beneficial physicochemical properties viz. non-toxicity, high surface area, efficient adsorption capability, high swellability, high dispersibility, thixotropic behaviour, and cation exchange capacity. Chemically modified clay provides significant opportunities in variety of applications. MMT finds very crucial place in pharmaceutical field owing to its medicinal properties, which may be used to delay the drug release in chronic physiological conditions and the targeted drug release as well. It is also used to improve the dissolution rate of certain drug molecules, which increased the attention of the researchers to explore the MMT for drug delivery applications. MMT clay has been used as pharmaceutical aids viz. suspending agent, lubricant, anticaking agent, diluent, emulsifier, nanocomposites-forming material, and sometimes filler. MMT clay have been investigated in the fabrication of different pharmaceutical formulations viz. hydrogel, films, nanocomposites, and matrix-based systems. MMT has obtained industrial importance due to its adsorption property and also finds use in wastewater treatment. Other than this, MMT also finds applications in cosmetic industry, food industry, and paper industry. Considering the wide applicability of MMT, it is need of an hour to explore the MMT for further commercial exploitation.

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

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

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.

Instrumental and transcriptome analysis reveals the chemotherapeutic effects of doxorubicin-loaded black phosphate nanosheets on abiraterone-resistant prostate cancer

Prostate cancer is the second most common cause of cancer-related deaths in men and is common in most developed countries. Androgen deprivation therapy (ADT) that uses abiraterone acetate (AA) is an effective second-line treatment for prostate cancer. However, approximately 20-40% of patients develop primary resistance to abiraterone post-treatment. In this study, we aimed to understand the molecular mechanisms underlying the development of abiraterone resistance in prostate cancer cells and the potential use of black phosphorus nanosheets (BPNS) for treating abiraterone-resistant prostate cancer. We first established abiraterone-resistant prostate cancer PC-3 cells and found that these cells have higher migration ability than normal prostate cancer cells. Using comparative transcriptomic and bioinformatics analyses between abiraterone-sensitive PC-3 and abiraterone-resistant PC-3 cells, we highlighted the differentially expressed genes (DEGs) involved in the biological processes related to prostate gland morphogenesis, drug response, immune response, angiogenesis. We further studied the therapeutic effects of BPNS. Our results show that BPNS reduced the proliferation and migration of abiraterone-resistant PC-3 cells. Bioinformatics analysis, including gene ontology, Kyoto encyclopedia of genes and genomes enrichment analysis, and ingenuity pathway analysis (IPA) of the DEGs, suggested that BPNS treatment controlled cancer cell proliferation, metastasis, and oncogenic signaling pathways. Furthermore, the IPA gene network highlighted the involvement of the MMP family, ATF, and notch families in the anti-prostate cancer function of BPNS. Our findings suggest that BPNS may have a chemotherapeutic function in treating abiraterone-resistant prostate cancer.

Effective loading of incompatible drugs into nanosized vesicles: a strategy to allow concurrent administration of furosemide and midazolam in simulated clinical settings

The current study aims to assess the use of nanocarriers to limit drug incompatibilities in clinical settings, and thus eliminating serious clinical consequences (e.g., catheter obstruction and embolism), and enhancing in vivo bioavailability and efficacy. As a proof-of-concept, the impact of loading well-documented physically incompatible drugs (i.e., furosemide and midazolam) into nanosized vesicles on in vitro stability and in vivo bioavailability of the two drugs was investigated. Furosemide and midazolam were loaded into nanosized spherical vesicles at high entrapment efficiency (ca. 62-69%). The drug-loaded vesicles demonstrated a sustained drug release patterns, high physical stability and negligible hemolytic activity. Physical incompatibility was assessed by exploiting microscopic technique coupled with image processing and analysis, dynamic light scattering and laser Doppler anemometry. Incorporation of drugs separately inside the nanosized vesicles dramatically decreased size and number of the precipitated particles. In vivo, the niosomal drug mixture demonstrated a significant improvement in pharmacokinetic profiles of furosemide and midazolam compared to the mixed free drug solutions, as evidenced by their longer circulation half-lives and higher area under the plasma-concentration time curves of both drugs. Nanocarriers could provide an auspicious strategy for circumventing drug incompatibilities, thus reducing adverse reactions, hospitalization period and improving therapeutic outcomes.

ROS generation and p-38 activation contribute to montmorillonite-induced corneal toxicity in vitro and in vivo

BACKGROUND

Montmorillonite (Mt) and its derivatives are now widely used in industrial and biomedical fields. Therefore, safety assessments of these materials are critical to protect human health after exposure; however, studies on the ocular toxicity of Mt are lacking. In particular, varying physicochemical characteristics of Mt may greatly alter their toxicological potential. To explore the effects of such characteristics on the eyes, five types of Mt were investigated in vitro and in vivo for the first time, and their underlying mechanisms studied.

RESULTS

The different types of Mt caused cytotoxicity in human HCEC-B4G12 corneal cells based on analyses of ATP content, lactate dehydrogenase (LDH) leakage, cell morphology, and the distribution of Mt in cells. Among the five Mt types, Na-Mt exhibited the highest cytotoxicity. Notably, Na-Mt and chitosan-modified acidic Na-Mt (C-H-Na-Mt) induced ocular toxicity in vivo, as demonstrated by increases corneal injury area and the number of apoptotic cells. Na-Mt and C-H-Na-Mt also induced reactive oxygen species (ROS) generation in vitro and in vivo, as indicated by 2',7'-dichlorofluorescin diacetate and dihydroethidium staining. In addition, Na-Mt activated the mitogen-activated protein kinase signaling pathway. The pretreatment of HCEC-B4G12 cells with N-acetylcysteine, an ROS scavenger, attenuated the Na-Mt-induced cytotoxicity and suppressed p38 activation, while inhibiting p38 activation with a p38-specific inhibitor decreased Na-Mt-induced cytotoxicity.

CONCLUSIONS

The results indicate that Mt induces corneal toxicity in vitro and in vivo. The physicochemical properties of Mt greatly affect its toxicological potential. Furthermore, ROS generation and p38 activation contribute at least in part to Na-Mt-induced toxicity.

Tacrolimus Loaded Cationic Liposomes for Dry Eye Treatment

Eye drops are ophthalmic formulations routinely used to treat dry eye. However, the low ocular bioavailability is an obvious drawback of eye drops owing to short ocular retention time and weak permeability of the cornea. Herein, to improve the ocular bioavailability of eye drops, a cationic liposome eye drop was constructed and used to treat dry eye. Tacrolimus liposomes exhibit a diameter of around 300 nm and a surface charge of +30 mV. Cationic liposomes could interact with the anionic ocular surface, extending the ocular retention time and improving tacrolimus amount into the cornea. The cationic liposomes notably prolonged the ocular retention time of eye drops, leading to an increased tacrolimus concentration in the ocular surface. The tacrolimus liposomes were also demonstrated to reduce reactive oxygen species and dry eye-related inflammation factors. The use of drug-loaded cationic liposomes is a good formulation in the treatment of ocular disease; the improved ocular retention time and biocompatibility give tremendous scope for application in the treatment of ocular disease, with further work in the area recommended.

Green Synthesis of Gold Nanoparticles Using Plant Extracts as Beneficial Prospect for Cancer Theranostics

Gold nanoparticles (AuNPs) have been widely explored and are well-known for their medical applications. Chemical and physical synthesis methods are a way to make AuNPs. In any case, the hunt for other more ecologically friendly and cost-effective large-scale technologies, such as environmentally friendly biological processes known as green synthesis, has been gaining interest by worldwide researchers. The international focus on green nanotechnology research has resulted in various nanomaterials being used in environmentally and physiologically acceptable applications. Several advantages over conventional physical and chemical synthesis (simple, one-step approach to synthesize, cost-effectiveness, energy efficiency, and biocompatibility) have drawn scientists’ attention to exploring the green synthesis of AuNPs by exploiting plants’ secondary metabolites. Biogenic approaches, mainly the plant-based synthesis of metal nanoparticles, have been chosen as the ideal strategy due to their environmental and in vivo safety, as well as their ease of synthesis. In this review, we reviewed the use of green synthesized AuNPs in the treatment of cancer by utilizing phytochemicals found in plant extracts. This article reviews plant-based methods for producing AuNPs, characterization methods of synthesized AuNPs, and discusses their physiochemical properties. This study also discusses recent breakthroughs and achievements in using green synthesized AuNPs in cancer treatment and different mechanisms of action, such as reactive oxygen species (ROS), mediated mitochondrial dysfunction and caspase activation, leading to apoptosis, etc., for their anticancer and cytotoxic effects. Understanding the mechanisms underlying AuNPs therapeutic efficacy will aid in developing personalized medicines and treatments for cancer as a potential cancer therapeutic strategy.

Antibacterial Activity and Mechanism of ZnO/Cu2+-Chitosan/Montmorillonite

A new composite antibacterial material ZnO/Cu²⁺-Chitosan/Montmorillonite (ZCCM) was prepared with montmorillonite as carrier, Zn(Ac)₂•2H₂O, Cu(NO₃)₂•3H₂O and chitosan as raw materials. ZCCM was characterized by X-ray diffraction, nitrogen physical adsorption, scanning electron microscopy and energy dispersion spectrometry. The antibacterial activity of ZCCM against Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus was evaluated by minimal inhibitory concentration, minimum bactericidal concentration and the influence of growth curves. ZCCM displays excellent antibacterial activity which is higher than ZnO-Montmorillonite, Cu²⁺-Montmorillonite and ZnO/Cu²⁺-Montmorillonite. In addition, the antibacterial mechanism of ZCCM was investigated by analyzing bacterial morphology, integrity of cell membrane, lipid peroxidation and the effect of histidine on antibacterial activity of materials. It is found that cell morphologies of bacteria are damaged and bacterial cells are shrunken. With the increase of cell membrane permeability, the intracellular dissolved matters leak continuously. What's more, the reactive oxygen species are generated and biomacromolecules are oxidized.

Incorporation of ion exchange functionalized-montmorillonite into solid lipid nanoparticles with low irritation enhances drug bioavailability for glaucoma treatment

Montmorillonite-loaded solid lipid nanoparticles with good biocompatibility, using Betaxolol hydrochloride as model drug, were prepared by the melt-emulsion sonication and low temperature-solidification methods and drug bioavailability was significantly improved in this paper for the first time to application to the eye. The appropriate physical characteristics were showed, such as the mean particle size, Zeta potential, osmotic pressure, pH values, entrapping efficiency (EE%) and drug content (DC%), all showed well suited for possible ocular application. In vitro release experiment indicated that this novel system could continuously release 57.83% drugs within 12 h owing to the dual drug controlled-release effect that was achieved by ion-exchange feature of montmorillonite and structure of solid lipid nanoparticles. Low irritability and good compatibility of nanoparticles were proved by both CAM-TBS test and cytotoxicity experiment. We first discovered from the results of Rose Bengal experiment that the hydrophilicity of the drug-loaded nanoparticles surface was increased during the loading and releasing of the hydrophilic drug, which could contribute to prolong the ocular surface retention time of drug in the biological interface membrane of tear-film/cornea. The results of in vivo pharmacokinetic and pharmacodynamics studies further confirmed that increased hydrophilicity of nanoparticles surface help to improve the bioavailability of the drug and reduce intraocular pressure during administration. The results suggested this novel drug delivery system could be potentially used as an in situ drug controlled-release system for ophthalmic delivery to enhance the bioavailability and efficacy.

Strategies to prolong the residence time of drug delivery systems on ocular surface

Ocular diseases may be treated via different routes of administration, such as topical, intracameral, intravitreal, oral and parenteral. Among them the topical route is most accepted by patients, although it provides in many cases the lowest bioavailability. Indeed, when a topical formulation reaches the precorneal area, i.e., the drug absorption and/or action site, it is rapidly eliminated due to eye protection mechanisms such as blinking, basal and reflex tearing, and naso-lacrimal draining. To avoid this and to reduce the frequency of dosing, various strategies have been developed to prolong drug residence time after topical administration. These strategies include the use of viscosity increasing and mucoadhesive excipients as well as combinations thereof. From the drug delivery system point of view, liquid and semisolid formulations are preferred over solid formulations such as ocular inserts and contact lenses. Furthermore, liquid and semisolid formulations can contain nano- and microcarrier systems that contribute to a prolonged residence time. Within this review an overview about the different types of excipients and formulations as well as their performance in valid animal models and clinical trials is provided.

Micro-interaction of mucin tear film interface with particles: The inconsistency of pharmacodynamics and precorneal retention of ion-exchange, functionalized, Mt-embedded nano- and microparticles

Physiological reflexes and anatomical barriers render traditional eye drop delivery inefficient. We previously reported that drug-loaded nanoparticles and microspheres prepared from montmorillonite and Eudragit polymers exhibited good sustained-release and lowered intraocular pressure. Here, we compared the performance of optimized formulations to select the most suitable formulation for glaucoma therapy. We found that the microspheres had much higher encapsulation efficiency and drug loading than nanoparticles. Moreover, cytocompatibility experiments demonstrated that nanoparticles showed more severe cytotoxicity than microspheres, probably due to their smaller particles, enhanced cell uptake, and intracellular solubility. Interestingly, the pre-corneal retention time of nanoparticles reflected a clear advantage over microspheres, while the duration of the pharmacological effect of nanoparticles was not as good as that of microspheres: compared with the nanoparticle depressurization duration of only 8 h, the microspheres continuously depressurized for 12 h. The slower release of the microspheres and its micro-interaction mechanism with the discontinuous mucin layer of the tear film led to the inconsistency between duration of pharmacodynamics and fluorescence ocular retention time. In summary, the lower cytotoxicity and longer pharmacological effect of microspheres indicate their potential advantages for glaucoma applications.

Curcumin encapsulated dual cross linked sodium alginate/montmorillonite polymeric composite beads for controlled drug delivery

The aim of the present work is fabrication of dual cross linked sodium alginate (SA)/montmorillonite (MMT) microbeads as a potential drug vehicle for extended release of curcumin (CUR). The microbeads were prepared using in situ ion-exchange followed by simple ionotropic gelation technique. The developed beads were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (X-RD) and scanning electron microscopy (SEM). The effect of MMT on encapsulation efficiency of CUR and intercalation kinetics was investigated. Dynamic swelling study and in vitro release study were investigated in simulated intestinal fluid (pH 7.4) and simulated gastric fluid (pH 1.2) at 37 °C. Results suggested that both the swelling and in vitro release studies were influenced by the pH of test media, which might be suitable for intestinal drug delivery. The release mechanism was analyzed by fitting the release data into Korsmeyer-Peppas equation.

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The microbeads prepared using sodium alginate (SA)/montmorillonite (MMT) were found to be potentially good carriers of curcumin (CUR) for extended release of CUR.

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The bioavailability of CUR is increased by the usage of MMT in the microbeads, hence making it possible to enhance the anti-tumour activity.

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The incorporation of multivalent ions like Mg²⁺, Ba²⁺ and Al³⁺ into calcium alginate matrix modified the swelling property and release rate of bio-active molecules.

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The porous nature of the microbeads was based on the size and interaction of the ions namely Mg²⁺, Ba²⁺ and Al³⁺ with alginate.

Effective Chemotherapy of Lung Cancer Using Bovine Serum Albumin-Coated Hydroxyapatite Nanoparticles

Background

Successful chemotherapy of lung cancer relies largely on the use of a good drug delivery system (DDS). We successfully constructed a hybrid DDS comprised of hydroxyapatite (HAP) nanoparticles and bovine serum albumin (BSA).

Material/Methods

The HAP nanoparticles were selected as the core to encapsulate the anticancer drug doxorubicin (DOX), followed by surface modification of BSA as a stabilizer and shielding corona to finally prepare the hybrid DDS (BSA/HAP/DOX).

Results

The following characterizations revealed that BSA/HAP nanoparticles have high stability, high biocompatibility, and good DOX-loading capability to meet in vivo applications. Moreover, BSA/HAP/DOX can enhance the cellular uptake of drug in A549 cells (lung cancer cells). Most importantly, BSA/HAP had better in vivo tumor targetability than bare HAP nanoparticles, which resulted in stronger anticancer efficacy both in vitro and in vivo than free DOX or HAP/DOX, and greatly decreased the adverse effects of free DOX.

Conclusions

Our hybrid DDS shows potential to be applied in more advanced application of cancer therapy.

Folic acid decorated metal-organic frameworks loaded with doxorubicin for tumor-targeted chemotherapy of osteosarcoma

Effective cancer therapy usually requires the assistance of well-designed drug carriers. In order to increase the drug accumulation to tumor tissue as well as to reduce the side effects of drug carriers, the hybrid drug delivery system (DDS) was developed by integrating folic acid (FA) and a metal-organic framework (MOF). The anticancer drug doxorubicin (DOX) was preloaded into the MOF nanoparticles during the synthesis process of the MOF nanoparticles. After surface modification with FA, the resulting FA/MOF/DOX nanoparticles were capable of serving as a biocompatible osteosarcoma targeting a DDS to enhance the chemotherapy of osteosarcoma. The dynamic light scattering method revealed that the obtained FA/MOF/DOX nanoparticles were particles with a size around 100 nm. Moreover, FA/MOF/DOX nanoparticles could enhance the delivery efficacy of DOX into MG63 (human osteosarcoma) cells as compared to FA free nanoparticles (MOF/DOX), in which a folate receptor (FR) might be involved. It was worth mentioning that in vitro [methylthio tetrazole (MTT) study in the MG63 cells] and in vivo (anticancer study in the MG63 xenograft model) assays both revealed that FA/MOF/DOX nanoparticles possessed stronger anticancer capability than free DOX or MOF/DOX nanoparticles.

Potential application of liposomal nanodevices for non-cancer diseases: an update on design, characterization and biopharmaceutical evaluation

Liposomes, lipid-based vesicular systems, have attracted major interest as a means to improve drug delivery to various organs and tissues in the human body. Recent literature highlights the benefits of liposomes for use as drug delivery systems, including encapsulating of both hydrophobic and hydrophilic cargos, passive and active targeting, enhanced drug bioavailability and therapeutic effects, reduced systemic side effects, improved cargo penetration into the target tissue and triggered contents release. Pioneering work of liposomes researchers led to introduction of long-circulating, ligand-targeted and triggered release liposomes, as well as, liposomes containing nucleic acids and vesicles containing combination of cargos. Altogether, these findings have led to widespread application of liposomes in a plethora of areas from cancer to conditions such as cardiovascular, neurologic, respiratory, skin, autoimmune and eye disorders. There are numerous review articles on the application of liposomes in treatment of cancer, which seems the primary focus, whereas other diseases also benefit from liposome-mediated treatments. Therefore, this article provides an illustrated detailed overview of liposomal formulations, in vitro characterization and their applications in different disorders other than cancer. Challenges and future directions, which must be considered to obtain the most benefit from applications of liposomes in these disorders, are discussed.

Glaucoma: Current treatment and impact of advanced drug delivery systems

The human eye being a complex and a very sensitive organ makes the drug delivery task challenging. An increase in the intra-ocular pressure at the aqueous humour leads to glaucoma which is not only indecipherable but can also be the reason of blindness for many. The presently available marketed formulations using anti-glaucoma drugs have issues of either difficulty in crossing the blood- retinal barrier or lower systemic bioavailability. Hence, the drugs having lower therapeutic index would need to be administered frequently, which eventually lead to deposition of concentrated solutions at ocular site, producing toxic effects and cellular damage to the eye. To overcome these drawbacks the novel drug delivery systems like In-situ gels, liposomes, niosomes, hydrogel, dendrimers, nanoparticles, solid lipid nanoparticles, Microneedles or ocular inserts play an important role to enhance the therapeutic efficacy of the anti-glaucomic drugs. The present review briefs the current treatments in terms of drugs used and in detail the impact of utilizing the above mentioned novel drug delivery systems in the treatment of glaucoma.

Nano-Based Drug Delivery System: Recent Strategies for the Treatment of Ocular Disease and Future Perspective

The structure of the eye is very complex in nature which makes it a challenging task for pharmaceutical researchers to deliver the drug at the desired sites via different routes of administration. The development of the nano-based system helped in delivering the drug in the desired concentration. Improvement in penetration property, bioavailability, and residence time has all been achieved by encapsulating drugs into liposomes, dendrimers, solid lipid nanoparticle, nanostructured lipid carrier, nanoemulsion, and nanosuspension. This review puts emphasis on the need for nanomedicine for ocular drug delivery and recent developments in the field of nanomedicine along with recent patents published in the past few years.

Liposome: composition, characterisation, preparation, and recent innovation in clinical applications

In the last decades, pharmaceutical interested researches aimed to develop novel and innovative drug delivery techniques in the medical and pharmaceutical fields. Recently, phospholipid vesicles (Liposomes) are the most known versatile assemblies in the drug delivery systems. The discovery of liposomes arises from self-forming enclosed phospholipid bilayer upon coming in contact with the aqueous solution. Liposomes are uni or multilamellar vesicles consisting of phospholipids produced naturally or synthetically, which are readily non-toxic, biodegradable, and are readily produced on a large scale. Various phospholipids, for instance, soybean, egg yolk, synthetic, and hydrogenated phosphatidylcholine consider the most popular types used in different kinds of formulations. This review summarises liposomes composition, characterisation, methods of preparation, and their applications in different medical fields including cancer therapy, vaccine, ocular delivery, wound healing, and some dermatological applications.

Inner layer-embedded contact lenses for ion-triggered controlled drug delivery

Drug leakage during manufacturing and storage process is the main obstacle hindering the application of contact lenses as the carrier for extended ocular drug delivery. In this study, we have designed a novel inner layer-embedded contact lens capable of ion-triggered drug release for extended ocular drug delivery. Using betaxolol hydrochloride as a drug model, drug-ion exchange resin complex dispersed polymer film was used as an inner layer, and silicone hydrogel was used as an outer layer to fabricate inner layer-embedded contact lens. Influence of composition of the inner film and crosslinking degree of the outer hydrogel on drug release profile was studied and optimized for weekly use. The ion-triggered drug eluting property enables the inner layer-embedded contact lens being stable when stored in distilled water at 5 °C for at least 30 days with ignorable drug loss and negligible changes in drug release kinetics. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 168 h in tear fluid, indicating significant improvement in drug corneal residence time. A level A IVIVC was established between in vitro drug release and in vivo drug concentration in tear fluid. In conclusion, this inner layer embedded contact lens design could be used as a platform for extended ocular drug delivery with translational potential for both anterior and posterior ocular disease therapy.

Montmorillonite/chitosan nanoparticles as a novel controlled-release topical ophthalmic delivery system for the treatment of glaucoma

Background

To date, the rapid clearance from ocular surface has been a huge obstacle for using eye drops to treat glaucoma, since it has led to the short preocular residence time and low bioavailability.

Methods

The novel nanoparticles (NPs) were designed for topical ophthalmic controlled drug delivery system through intercalating the BH into the interlayer gallery of Na-montmorillonite (Na+Mt) and then further enchasing chitosan nanoparticles. The resulting nanoparticles had a positive charge (+29±0.18 mV) with an average diameter of 460±0.6 nm.

Results

In vitro study of drug release profiles suggested controlled release pattern. The irritation experiment analysis on both human immortalized cornea epithelial cell (iHCEC) and chorioallantoic membrane-trypan blue staining (CAM-TBS) showed good tolerance for ocular tissues. It was interestingly found that the nanoparticles could enter into iHCEC from the result of cellular uptake experiment measured by confocal layer scan microscopy (CLSM). Meanwhile, multilayered iHCEC was used to simulate the barrier of corneal epithelial cells for in vivo preocular retention capacity study, which suggested that BH-Mt/CS NPs could prolong the retention time in comparison with BH solution. The ocular pharmacokinetics studied by microdialysis sampling technique showed that AUC_0-t and MRT_0-t of BH-Mt/CS NPs were 1.99-fold and 1.75-fold higher than those of BH solution, indicating higher bioavailability. Moreover, the study of blood drug concentration, few researchers have reported, showed that low level drug could enter into blood, suggesting lower systematic side effect. Importantly, pharmacodynamics studies suggested that BH-Mt/CS NPs could make a significant decreased intraocular pressure on glaucomatous rabbits.

Conclusion

Inspired by these advance of montmorillonite/chitosan nanoparticles, we envision that the BH-Mt/CS NPs will be a potential carrier for BH, opening up the possible applications in glaucoma therapy.

Nanoliposome-Encapsulated Brinzolamide-hydropropyl-β-cyclodextrin Inclusion Complex: A Potential Therapeutic Ocular Drug-Delivery System

Novel ocular drug delivery systems (NODDSs) remain to be explored to overcome the anatomical and physiological barriers of the eyes. This study was to encapsulate brinzolamide (BRZ)-hydropropyl-β-cyclodextrin (HP-β-CD) inclusion complex (HP-β-CD/BRZ) into nanoliposomes and investigate its potential as one of NODDS to improve BRZ local glaucomatous therapeutic effect. HP-β-CD/BRZ was firstly prepared to enhance the solubility of poorly water-soluble BRZ. The HP-β-CD/BRZ loaded nanoliposomes (BCL) were subsequently constructed by thin-film dispersion method. After the optimization of the ratio of BRZ to HP-β-CD, the optimal BCL showed an average size of 82.29 ± 6.20 nm, ζ potential of -3.57 ± 0.46 mV and entrapment efficiency (EE) of 92.50 ± 2.10% with nearly spherical in shape. The X-ray diffraction (XRD) confirmed the formation of HP-β-CD/BRZ and BCL. The in vitro release study of BCL was evaluated using the dialysis technique, and BCL showed moderate sustained release. BCL (1 mg/mL BRZ) showed a 9.36-fold increase in the apparent permeability coefficient and had a sustained and enhanced intraocular pressure reduction efficacy when compared with the commercially available formulation (BRZ-Sus) (10 mg/mL BRZ). In conclusion, BCL might have a promising future as a NODDS for glaucoma treatment.

Controlled drug delivery for glaucoma therapy using montmorillonite/Eudragit microspheres as an ion-exchange carrier

Background

Glaucoma is a serious eye disease that can lead to loss of vision. Unfortunately, effective treatments are limited by poor bioavailability of antiglaucoma medicine due to short residence time on the preocular surface.

Materials and methods

To solve this, we successfully prepared novel controlled-release ion-exchange microparticles to deliver betaxolol hydrochloride (BH). Montmorillonite/BH complex (Mt-BH) was prepared by acidification-intercalation, and this complex was encapsulated in microspheres (Mt-BH encapsulated microspheres [BMEMs]) by oil-in-oil emulsion-solvent evaporation method. The BH loaded into ion-exchange Mt was 47.45%±0.54%. After the encapsulation of Mt-BH into Eudragit microspheres, the encapsulation efficiency of BH into Eudragit microspheres was 94.35%±1.01% and BH loaded into Eudragit microspheres was 14.31%±0.47%.

Results

Both Fourier transform infrared spectra and X-ray diffraction patterns indicated that BH was successfully intercalated into acid-Mt to form Mt-BH and then Mt-BH was encapsulated into Eudragit microspheres to obtain BMEMs. Interestingly, in vitro release duration of the prepared BMEMs was extended to 12 hours, which is longer than both of the BH solution (2.5 hours) and the conventional BH microspheres (5 hours). Moreover, BMEM exhibited lower toxicity than that of BH solution as shown by the results of cytotoxicity tests, chorioallantoic membrane-trypan blue staining, and Draize rabbit eye test. In addition, both in vivo and in vitro preocular retention capacity study of BMEMs showed a prolonged retention time. The pharmacodynamics showed that BMEMs could extend the drug duration of action.

Conclusion

The developed BMEMs have the potential to be further applied as ocular drug delivery systems for the treatment of glaucoma.

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.