In situ gel systems as 'smart' carriers for sustained ocular drug delivery

Development of a Temperature and pH Dual-Sensitive In-Situ Gel for Treating Allergic Conjunctivitis

The purpose of this study was to improve the efficacy of olopatadine hydrochloride (OT) in treating allergic conjunctivitis (AC). To achieve this goal, we developed an eye formulation without antimicrobial agents using a temperature-pH dual-sensitive in situ gel technology combined with heat sterilization. Various types of carbomers were evaluated and their optimal doses determined. The prescription containing poloxamer 407 (P407) and poloxamer 188 (P188) was optimized using central composite design for response surface methodology (CCD-RSM). The final optimized dual-sensitive in situ gel (TP-gel) consisted of 0.1% olopatadine hydrochloride, 18.80% P407, 0.40% P188, 0.30% Pemulen™TR-1(TR-1), 4.0% mannitol, and 0.08% Tri(hydroxymethyl)aminomethane(Tris).Sterilization was performed at a temperature of 121℃ for a duration of 20 min. Experimental results showed that TP-gel had good safety profile and remained on the ocular surface for approximately (65.83 ± 8.79) minutes, which is four times longer than eye drops. The expression levels of IL-13, IL-17, and OVA-IgE in mouse ocular tissues with allergic conjunctivitis treated with TP-gel were significantly reduced. This suggests that TP-gel has the potential to be an effective treatment method for allergic conjunctivitis.

Long-Term Safety and Efficacy Evaluation of Travoprost Intracameral Implant Based on Pooled Analyses from Two Phase III Trials

AIM

The purpose of this study was to conduct and interpret a pooled 12-month analysis of two prospective, multi-center, randomized, double-masked, controlled trials designed to assess the efficacy and safety of the travoprost intracameral implant (slow-eluting [SE] implant in development as a new therapeutic and fast-eluting [FE] implant included for masking purposes) in subjects with open-angle glaucoma (OAG) or ocular hypertension (OHT).

METHODS

Subjects with OAG or OHT, on 0-3 intraocular pressure (IOP)-lowering medications, baseline unmedicated mean diurnal IOP of ≥ 21 mmHg, and IOP ≤ 36 mmHg at each baseline diurnal timepoint, received either a travoprost implant and twice-daily (BID) placebo eye drops or BID timolol 0.5% eye drops and a sham procedure. Subjects were followed through 12 months and assessed for IOP, reduction in topical IOP-lowering medications, and safety parameters including treatment-emergent adverse events (TEAEs). IOP at 8AM was prospectively collected at all study visits through 12 months and diurnal IOP, measured at 8AM, 10AM, and 4PM, was prospectively collected at baseline, day 10, week 6, and months 3 and 12.

RESULTS

A total of 1150 subjects were randomized (385 FE implant, 380 SE implant, and 385 sham/timolol) across the two trials. Statistical non-inferiority to timolol and clinically relevant reductions in 8AM IOPs were demonstrated at month 12. In more detail, both implant groups demonstrated statistical non-inferiority to timolol and clinically relevant reductions from baseline in mean diurnal IOP at all visits over the 12-month evaluation period when diurnal IOP was collected. Additionally, both implant groups demonstrated robust treatment effect based on 8AM average IOP from day 10 through the specified visit which ranged from day 10 to month 12 from 6.9 to 8.5 mmHg in the FE implant group; 6.8 to 8.5 mmHg in the SE implant group; and 7.3 to 7.5 mmHg in the sham/timolol group. With regards to reduction in topical pharmacotherapy, at month 12, 77.6% of FE and 81.4% of SE implant eyes were completely free of all topical IOP-lowering medications and a significantly greater proportion of FE and SE implant eyes (89.9% and 93.0%) versus sham/timolol eyes (66.9%) were on the same or fewer topical IOP-lowering medications compared with pre-study (p <  0.0001). Furthermore, of subjects on topical IOP medications at screening, a significantly greater proportion of FE implant (80.2%) and SE implant (85.1%) eyes versus sham/timolol (22.8%) eyes were on fewer topical IOP-lowering medications at month 12 compared with pre-study (p <  0.0001). Lastly, of SE implant eyes on same or fewer topical IOP-lowering medications at month 12, the average through month 12 decreased by 0.9 medications, and of those SE implant eyes on fewer topical IOP-lowering medications compared with pre-study, the average through month 12 decreased by 1.4 medications. The most common TEAEs related to study treatment were hyperemia (conjunctival or ocular), iritis, and IOP increased.

CONCLUSION

The travoprost intracameral implant demonstrated robust IOP-lowering efficacy that was sustained and statistically non-inferior to timolol over the entire 12 months, resulting in a significant reduction in topical IOP-lowering medication use, with the majority of SE implant eyes remaining completely free of all topical IOP-lowering medications. In addition, the implant demonstrated a favorable safety and tolerability profile based on this pooled 12-month analysis of two pivotal trials.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers NCT03519386 (registered May 09, 2018) and NCT03868124 (registered March 08, 2019).

Autophagy in cancer immunotherapy: Perspective on immune evasion and cell death interactions

Both the innate and adaptive immune systems work together to produce immunity. Cancer immunotherapy is a novel approach to tumor suppression that has arisen in response to the ineffectiveness of traditional treatments like radiation and chemotherapy. On the other hand, immune evasion can diminish immunotherapy's efficacy. There has been a lot of focus in recent years on autophagy and other underlying mechanisms that impact the possibility of cancer immunotherapy. The primary feature of autophagy is the synthesis of autophagosomes, which engulf cytoplasmic components and destroy them by lysosomal degradation. The planned cell death mechanism known as autophagy can have opposite effects on carcinogenesis, either increasing or decreasing it. It is autophagy's job to maintain the balance and proper functioning of immune cells like B cells, T cells, and others. In addition, autophagy controls whether macrophages adopt the immunomodulatory M1 or M2 phenotype. The ability of autophagy to control the innate and adaptive immune systems is noteworthy. Interleukins and chemokines are immunological checkpoint chemicals that autophagy regulates. Reducing antigen presentation to induce immunological tolerance is another mechanism by which autophagy promotes cancer survival. Therefore, targeting autophagy is of importance for enhancing potential of cancer immunotherapy.

Design and Evaluation of a Dual-Sensitive In Situ Gel for the Controlled Release of Pranoprofen

Currently, the marketed ophthalmic preparations of pranoprofen (PF) are mainly eye drops, but due to the special clearance mechanism of the eye and corneal reflex, the contact time between the drug and the focal site is short, most of the drug is lost, and the bioavailability is less than 5%. In the present study, an in situ gel eye drop containing no bacteriostatic agent and sensitive to temperature and ions was designed for delivery of PF. It was demonstrated to meet the criteria for ophthalmic preparations by characterization such as appearance content sterility. Ocular irritation tests showed a favorable safety profile. In vivo ocular retention time experiments showed that the ocular retention time of the pranoprofen gel was 4.41 times longer than that of commercially available drops (Pranopulin®), and the nasal tear excretion of the pranoprofen gel was lower than that of Pranopulin®, which suggests that the drug loss was reduced relative to that of the drops. The efficacy of the pranoprofen gel against tincture of cayenne pepper-induced corneal and conjunctival inflammation was examined using Pranopulin® as a control and in conjunction with inflammation scores, H&E slice results, and levels of IL-1β, IL-6, and TNF-α. The results showed that pranoprofen gel and Pranololin® had significant efficacy in the treatment of corneal and conjunctival inflammation, and the anti-inflammatory effect of pranoprofen gel was superior to that of Pranololin®. This study provides a new option for the treatment of corneal and conjunctival inflammation.

Gastric acid-responsive deformable sodium alginate/Bletilla striata polysaccharide in situ gel for the protection and treatment of alcohol-induced peptic ulcers

First-line drugs for peptic ulcer (PU) treatment are typically limited by poor targeting and adverse effects associated with long-term use. Despite recent advancements in novel therapeutic approaches for PU, the development of sustained-release delivery systems tailored to specific pathological characteristics remains challenging. Persistent inflammation, particularly gastric inflammatory microenvironment imbalance, characterizes the PU. In this study, we prepared an in situ gel composed of sodium alginate, deacetylated gellan gum, calcium citrate, and Bletilla striata polysaccharide (BSP) to achieve sustained release of BSP. The BSP in situ gel demonstrated favorable fluidity in vitro and completed self-assembly in vivo in response to the acidic milieu at a pH of 1.5. Furthermore, the shear, extrusion, and deformation properties increased by 26.4 %, 103.7 %, and 46.3 %, respectively, with long-term gastric retention (4 h) and mucosal adaptation. Animal experiments confirmed that the BSP in situ gel could attenuate necrotic injury and inflammatory cell infiltration, maintain mucosal barrier integrity, regulate cytokine imbalance and inflammation-associated hyperapoptosis, thus effectively alleviate the inflammatory microenvironmental imbalance in PU without significant side effects. Overall, our findings demonstrated that the BSP in situ gel is a promising therapeutic strategy for PU and opens avenues for developing self-assembled formulations targeting the pathological features of PUs.

Gel/hydrogel-based in situ biomaterial platforms for cancer postoperative treatment and recovery

Tumor surgical resection is the major strategy for cancer treatment. Meanwhile, perioperative treatment especially the postoperative adjuvant anticancer strategies play essential roles in satisfying therapeutic results and rapid recovery. Postoperative tumor recurrence, metastasis, bleeding, inter-tissue adhesion, infection, and delayed wound healing are vital risks that could lead to poor prognosis or even treatment failure. Therefore, methods targeting these postoperative complications are in desperate need. In situ biomaterial-based drug delivery platforms are promising candidates for postoperative treatment and recovery, resulting from their excellent properties including good biocompatibility, adaptive shape, limited systemic effect, designable function, and easy drug loading. In this review, we focus on introducing the gel/hydrogel-based in situ biomaterial platforms involving their properties, advantages, and synthesis procedures. Based on the loaded contents in the gel/hydrogel such as anticancer drugs, immunologic agents, cell components, and multifunctional nanoparticles, we further discuss the applications of the in situ platforms for postoperative tumor recurrence and metastasis inhibition. Finally, other functions aiming at fast postoperative recovery were introduced, including hemostasis, antibacterial infection, adhesion prevention, tissue repair, and wound healing. In conclusion, gel/hydrogel is a developing and promising platform for postoperative treatment, exhibiting gratifying therapeutic effects and inconspicuous toxicity to normal tissues, which deserves further research and exploration.

Polymeric in situ forming depots for long-acting drug delivery systems

Polymeric in situ forming depots have emerged as highly promising drug delivery systems for long-acting applications. Their effectiveness is attributed to essential characteristics such as biocompatibility, biodegradability, and the ability to form a stable gel or solid upon injection. Moreover, they provide added versatility by complementing existing polymeric drug delivery systems like micro- and nanoparticles. The formulation's low viscosity facilitates manufacturing unit operations and enhances delivery efficiency, as it can be easily administered via hypodermic needles. The release mechanism of drugs from these systems can be predetermined using various functional polymers. To enable unique depot design, numerous strategies involving physiological and chemical stimuli have been explored. Important assessment criteria for in situ forming depots include biocompatibility, gel strength and syringeability, texture, biodegradation, release profile, and sterility. This review focuses on the fabrication approaches, key evaluation parameters, and pharmaceutical applications of in situ forming depots, considering perspectives from academia and industry. Additionally, insights about the future prospects of this technology are discussed.

Biodegradable Polymer-Based Drug-Delivery Systems for Ocular Diseases

Ocular drug delivery is a challenging field due to the unique anatomical and physiological barriers of the eye. Biodegradable polymers have emerged as promising tools for efficient and controlled drug delivery in ocular diseases. This review provides an overview of biodegradable polymer-based drug-delivery systems for ocular diseases with emphasis on the potential for biodegradable polymers to overcome the limitations of conventional methods, allowing for sustained drug release, improved bioavailability, and targeted therapy. Natural and synthetic polymers are both discussed, highlighting their biodegradability and biocompatibility. Various formulation strategies, such as nanoparticles, hydrogels, and microemulsions, among others, are investigated, detailing preparation methods, drug encapsulation, and clinical applications. The focus is on anterior and posterior segment drug delivery, covering glaucoma, corneal disorders, ocular inflammation, retinal diseases, age-related macular degeneration, and diabetic retinopathy. Safety considerations, such as biocompatibility evaluations, in vivo toxicity studies, and clinical safety, are addressed. Future perspectives encompass advancements, regulatory considerations, and clinical translation challenges. In conclusion, biodegradable polymers offer potential for efficient and targeted ocular drug delivery, improving therapeutic outcomes while reducing side effects. Further research is needed to optimize formulation strategies and address regulatory requirements for successful clinical implementation.

Novel Drug Delivery Methods and Approaches for the Treatment of Retinal Diseases

This review discusses emerging approaches to ocular drug delivery for retinal diseases. Intravitreal injections have proven to be an effective, safe, and commonly used drug delivery method. However, the optimal management of chronic retinal diseases requires frequent intravitreal injections over extended periods of time. Although this can be achieved in a clinical trial environment, it is difficult to replicate in routine clinical practice. In addition, frequent treatment increases the risk of complications, incurs more costs, and increases the treatment burden for patients and caregivers. Given the aging global population and diabetes pandemic, there is an urgent need for drug delivery methods that support more durable retinal therapy while maintaining the efficacy and safety of currently available intravitreal therapies. Several innovative drug delivery methods are currently being investigated. These include sustained-release implants and depots using prodrugs, microparticles, and hydrogels, surgically implanted reservoirs, gene therapy via submacular injections or suprachoroidal injections, as well as topical and systemic therapies.

Recent advancements in nanotechnology-based bacteriophage delivery strategies against bacterial ocular infections

Antibiotic resistance is growing as a critical challenge in a variety of disease conditions including ocular infections leading to disastrous effects on the human eyes. Staphylococcus aureus (S. aureus) mediated ocular infections are very common affecting different parts of the eye viz. vitreous chamber, conjunctiva, cornea, anterior and posterior chambers, tear duct, and eyelids. Blepharitis, dacryocystitis, conjunctivitis, keratitis, endophthalmitis, and orbital cellulitis are some of the commonly known ocular infections caused by S. aureus. Some of these infections are so fatal that they could cause bilateral blindness like panophthalmitis and orbital cellulitis, which is caused by methicillin-resistant S. aureus (MRSA) and vancomycin-resistance S. aureus (VRSA). The treatment of S. aureus infections with known antibiotics is becoming gradually difficult because of the development of resistance against multiple antibiotics. Apart from the different combinations and formulation strategies, bacteriophage therapy is growing as an effective alternative to treat such infections. Although the superiority of bacteriophage therapy is well established, yet physical factors (high temperatures, acidic pH, UV-rays, and ionic strength) and pharmaceutical barriers (poor stability, low in-vivo retention, controlled and targeted delivery, immune system neutralization, etc.) have the greatest influence on the viability of phage virions (also phage proteins). A variety of Nanotechnology based formulations such as polymeric nanoparticles, liposomes, dendrimers, nanoemulsions, and nanofibres have been recently reported to overcome the above-mentioned obstacles. In this review, we have compiled all these recent reports and discussed bacteriophage-based nanoformulations techniques for the successful treatment of ocular infections caused by multidrug-resistant S. aureus and other bacteria.

Delivery Systems in Ocular Retinopathies: The Promising Future of Intravitreal Hydrogels as Sustained-Release Scaffolds

Slow-release delivery systems are needed to ensure long-term sustained treatments for retinal diseases such as age-related macular degeneration and diabetic retinopathy, which are currently treated with anti-angiogenic agents that require frequent intraocular injections. These can cause serious co-morbidities for the patients and are far from providing the adequate drug/protein release rates and required pharmacokinetics to sustain prolonged efficacy. This review focuses on the use of hydrogels, particularly on temperature-responsive hydrogels as delivery vehicles for the intravitreal injection of retinal therapies, their advantages and disadvantages for intraocular administration, and the current advances in their use to treat retinal diseases.

Hot-melt extruded in situ gelling systems (MeltDrops Technology): Formulation development, in silico modelling and in vivo studies

In situ gelling systems (ISGS) can prolong retention time and bioavailability of ophthalmic solutions. The complexity and cost of ISGS avert their industrial scale-up and clinical implementation. In this study, we demonstrate novel application of hot-melt extrusion (HME) technology for continuous manufacturing of ISGS (MeltDrops Technology). Timolol maleate (TIM) and dorzolamide hydrochloride (DRZ) loaded MeltDrops were successfully developed using HME for glaucoma management, thereby resolving issues with batch manufacturing of ISGS, prolonging retention time thus improving bioavailability. The MeltDrops technology involves one-step, i.e., passing all the ingredients through an extruder at a screw speed between 20-50 rpm and barrel temperature of 80 °C. The comparative evaluation of MeltDrops and batch-processed ISGS demonstrated that MeltDrops exhibited better physical and chemical content uniformity. The extrusion temperature and screw speed were critical factors influencing content uniformity and properties of the MeltDrops. MeltDrops showed sustained drug release for >12 hours in vitro (TIM= 83.07%; DRZ = 60.43%, 12hours) versus marketed eyedrops. The developed MeltDrops followed Peppas-Sahlin model, combining Fickian diffusion and swelling processes. The in vivo study in New Zealand rabbits revealed superior effectiveness and safety of the MeltDrops as compared to the marketed eyedrops. Herein we conclude, MeltDrops would serve as a cutting-edge platform technology that can be used to manufacture various ISGS with one-step processability, cost-effectiveness, and improved product quality, which are otherwise processed by batch manufacturing that involves numerous complex processing steps.

Recent Advances in Pharmaceutical Approaches of Antimicrobial Agents for Selective Delivery in Various Administration Routes

Globally, the increase of pathogenic bacteria with antibiotic-resistant characteristics has become a critical challenge in medical treatment. The misuse of conventional antibiotics to treat an infectious disease often results in increased resistance and a scarcity of effective antimicrobials to be used in the future against the organisms. Here, we discuss the rise of antimicrobial resistance (AMR) and the need to combat it through the discovery of new synthetic or naturally occurring antibacterial compounds, as well as insights into the application of various drug delivery approaches delivered via various routes compared to conventional delivery systems. AMR-related infectious diseases are also discussed, as is the efficiency of various delivery systems. Future considerations in developing highly effective antimicrobial delivery devices to address antibiotic resistance are also presented here, especially on the smart delivery system of antibiotics.

Nanotechnology based drug delivery systems for the treatment of anterior segment eye diseases

Diseases affecting the anterior segment of the eye are the primary causes of vision impairment and blindness globally. Drug administration through the topical ocular route is widely accepted because of its user/patient friendliness - ease of administration and convenience. However, it remains a significant challenge to efficiently deliver drugs to the eye through this route because of various structural and physiological constraints that restrict the distribution of therapeutic molecules into the ocular tissues. The bioavailability of topically applied ocular medications such as eye drops is typically less than 5%. Developing novel delivery systems to increase the retention time on the ocular surfaces and permeation through the cornea is one of the approaches adopted to boost the bioavailability of topically administered medications. Drug delivery systems based on nanotechnology such as micelles, nanosuspensions, nanoparticles, nanoemulsions, liposomes, dendrimers, niosomes, cubosomes and nanowafers have been investigated as effective alternatives to conventional ocular delivery systems in treating diseases of the anterior segment of the eye. This review discussed different nanotechnology-based delivery systems that are currently investigated for treating and managing diseases affecting the anterior ocular tissues. We also looked at the challenges in translating these systems into clinical use and the prospects of nanocarriers as a vehicle for the delivery of phytoactive compounds to the anterior segment of the eye.

Thermoresponsive in-situ gel containing hyaluronic acid and indomethacin for the treatment of corneal chemical burn

Ocular chemical burns are prevalent injuries that must have immediate and effective treatment to avoid complications. Aiming to improve bioavailability and efficacy, a poloxamer-based thermoresponsive in-situ gelling system containing hyaluronic acid and indomethacin was developed. Formulations with different polymeric proportions were screened through rheological measurements resulting in an optimized system (F2) with gelling temperature of 34.2 ± 0.11 °C. Its maximum viscosity varied from 77.33 mPa (25 °C) to 82.95 mPa (34 °C) following a non-Newtonian profile and a pH of 6.86 ± 0.01. No incompatibilities were found after infrared analysis. Polarized light microscopy and cryo-transmission electron microscopy have demonstrated micelles of nano-sized dimensions (21.86 nm) with indomethacin entrapped in the core, forming a polymeric network under heating. In vitro tests revealed a cumulative release of 59.75 ± 3.17 % up to 24 h under a sustained release profile. Results from HET-CAM assay indicated that F2 was well tolerated. Corneal wound healing was significantly faster in animals treated with F2 compared to a commercial formulation and an untreated group. These findings suggests that F2 could be an efficient system to delivery drugs into the ocular surface improving wound healing.

In-situ Gels for Brain Delivery: Breaching the Barriers

The blood-brain barrier (BBB) regulates blood and chemical exchange in the central nervous system. It is made up of brain parenchyma capillary endothelial cells. It separates the interstitial cerebrospinal fluid from the circulation and limits brain drug entry. Peptides, antibodies, and even tiny hydrophilic biomolecules cannot flow across the BBB due to their semi-permeability. It protects the brain from poisons, chemicals, and pathogens, and blood cells penetrate brain tissue. BBB-facilitated carrier molecules allow selective permeability of nutrients such as D-glucose, L-lactic acid, L-phenylalanine, L-arginine, and hormones, especially steroid hormones. Brain barriers prevent drug molecules from entering, making medication delivery difficult. Drugs can reach specific brain regions through the nasal cavity, making it a preferred route. The in-situ gels are mucoadhesive, which extends their stay in the nasal cavity, allows them to penetrate deep and makes them a dependable way of transporting numerous medications, including peptides and proteins, straight into the central nervous system. This approach holds great potential for neurological therapy as they deliver drugs directly to the central nervous system, with less interference and better drug release control. The brain affects daily life by processing sensory stimuli, controlling movement and behaviour, and sustaining mental, emotional, and cognitive functioning. Unlike systemic routes, the nasal mucosa is extensively vascularized and directly contacts olfactory sensory neurons. Compared to the systemic circulation, this improves brain bioavailability of medications. Drugs can be delivered to the brain using in-situ gel formulations safely and efficiently, with a greater therapeutic impact than with traditional techniques.

Potential therapeutic strategies for photoreceptor degeneration: the path to restore vision

Photoreceptors (PRs), as the most abundant and light-sensing cells of the neuroretina, are responsible for converting light into electrical signals that can be interpreted by the brain. PR degeneration, including morphological and functional impairment of these cells, causes significant diminution of the retina's ability to detect light, with consequent loss of vision. Recent findings in ocular regenerative medicine have opened promising avenues to apply neuroprotective therapy, gene therapy, cell replacement therapy, and visual prostheses to the challenge of restoring vision. However, successful visual restoration in the clinical setting requires application of these therapeutic approaches at the appropriate stage of the retinal degeneration. In this review, firstly, we discuss the mechanisms of PR degeneration by focusing on the molecular mechanisms underlying cell death. Subsequently, innovations, recent developments, and promising treatments based on the stage of disorder progression are further explored. Then, the challenges to be addressed before implementation of these therapies in clinical practice are considered. Finally, potential solutions to overcome the current limitations of this growing research area are suggested. Overall, the majority of current treatment modalities are still at an early stage of development and require extensive additional studies, both pre-clinical and clinical, before full restoration of visual function in PR degeneration diseases can be realized.

Nanotherapeutics in autophagy: a paradigm shift in cancer treatment

Autophagy is a catabolic process in which an organism responds to its nutrient or metabolic emergencies. It involves the degradation of cytoplasmic proteins and organelles by forming double-membrane vesicles called "autophagosomes." They sequester cargoes, leading them to degradation in the lysosomes. Although autophagy acts as a protective mechanism for maintaining homeostasis through cellular recycling, it is ostensibly a cause of certain cancers, but a cure for others. In other words, insufficient autophagy, due to genetic or cellular dysfunctions, can lead to tumorigenesis. However, many autophagy modulators are developed for cancer therapy. Diverse nanoparticles have been documented to induce autophagy. Also, the highly stable nanoparticles show blockage to autophagic flux. In this review, we revealed a general mechanism by which autophagy can be induced or blocked via nanoparticles as well as several studies recently performed to prove the stated fact. In addition, we have also elucidated the paradoxical roles of autophagy in cancer and how their differential role at different stages of various cancers can affect its treatment outcomes. And finally, we summarize the breakthroughs in cancer disease treatments by using metallic, polymeric, and liposomal nanoparticles as potent autophagy modulators.

Upper Airways Spray for Viral Infections Prevention

Aim

Several studies emphasized the antiviral properties of many natural compounds enclosed in nutraceuticals formulas and quite effective to prevent the respiratory infections. The rationale of our investigation has been to achieve protection from common cold viruses' infection of the upper airways pooling together and dispensing different active principles on a multistep defense basis. Material and Methods. 30 patients affected by sudden aspecific viral-induced sore throat rhinitis were divided in two groups: (1) the first group included 15 patients which were administered with our spray formula and (2) the second group included 15 patients with the commercial nasal lavage kit. The mucous smear was stained with May Grunwald-Giemsa to exclude eosinophilic infiltrate and confirm the prevalence of granulocytes and lympho-monocytes typical of viral seasonal inflammatory upper airways conditions.

Results

The symptomatic relieve is remarkedly evident in the treated group with our spray compared to the second group treated with commercial nasal lavage kit.

Conclusions

The open case-control retrospective observational study showed a definite benefit of the spray based on natural herbal extracts to take control of the upper airways respiratory distress due to viral infections.

Interpenetrating polymeric network (IPNs) in ophthalmic drug delivery: Breaking the barriers

To maintain the therapeutic drug concentration for a prolonged period of time in aqueous and vitreous humor is primary challenge for ophthalmic drug delivery. Majority of the locally administered drug into the eye is lost as to natural reflexes like blinking and lacrimation resulting in the short span of drug residence. Consequently, less than 5% of the applied drug penetrate through the cornea and reaches the intraocular tissues. The major targets for optimal ophthalmic drug delivery are increasing drug residence time in cul-de-sac of the eye, prolonging intraocular exposure, modulating drug release from the delivery system, and minimizing pre-corneal drug loss. Development of in situ gel, contact lens, intraocular lens, inserts, artificial cornea, scaffold, etc., for ophthalmic drug delivery are few approaches to achieve these major targeted objectives for delivering the drug optimally. Interpenetrating polymeric network (IPN) or smart hydrogels or stimuli sensitive hydrogels are the class of polymers that can help to achieve the targets in ophthalmic drug delivery due to their versatility, biocompatibility and biodegradability. These novel ''smart" materials can alter their molecular configuration and result in volume phase transition in response to environmental stimuli, such as temperature, pH, ionic strength, electric and magnetic field. Hydrogel and tissue interaction, mechanical/tensile properties, pore size and surface chemistry of IPNs can also be modulated for tuning the drug release kinetics. Stimuli sensitive IPNs has been widely exploited to prepare in situ gelling formulations for ophthalmic drug delivery. Low refractive index hydrogel biomaterials with high water content, soft tissue-like physical properties, wettability, oxygen, glucose permeability and desired biocompatibility makes IPNs versatile candidate for contact lenses and corneal implants. This review article focuses on the exploration of these smart polymeric networks/IPNs for therapeutically improved ophthalmic drug delivery that has unfastened novel arenas in ophthalmic drug delivery.

Long-acting formulation strategies for protein and peptide delivery in the treatment of PSED

The invigoration of protein and peptides in serious eye disease includes age-related macular degeneration, choroidal neovascularization, retinal neovascularization, and diabetic retinopathy. The transportation of macromolecules like aptamers, recombinant proteins, and monoclonal antibodies to the posterior segment of the eye is challenging due to their high molecular weight, rapid degradation, and low solubility. Moreover, it requires frequent administration for prolonged therapy. The long-acting novel formulation strategies are helpful to overcome these issues and provide superior therapy. It avoids frequent administration, improves stability, high retention time, and avoids burst release. This review briefly enlightens posterior segments of eye diseases with their diagnosis techniques and treatments. This article mainly focuses on recent advanced approaches like intravitreal implants and injectables, electrospun injectables, 3D printed drug-loaded implants, nanostructure thin-film polymer devices encapsulated cell technology-based intravitreal implants, injectable and depots, microneedles, PDS with ranibizumab, polymer nanoparticles, inorganic nanoparticles, hydrogels and microparticles for delivering macromolecules in the eye for intended therapy. Furthermore, novel techniques like aptamer, small Interference RNA, and stem cell therapy were also discussed. It is predicted that these systems will make revolutionary changes in treating posterior segment eye diseases in future.

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.

Combination Therapy Comprising Paclitaxel and 5-Fluorouracil by Using Folic Acid Functionalized Bovine Milk Exosomes Improves the Therapeutic Efficacy against Breast Cancer

Paclitaxel (PAC) has been approved by FDA for clinical use (Taxol^®), yet dose-dependent severe toxicity due to the adjuvant Cremophor EL^® in combination with ethanol is a major drawback. The drawbacks of the current therapy can be overcome by (i) finding a suitable vehicle that cannot only bypass the above adjuvant but also be used to deliver drugs orally and (ii) combining the PAC with some other chemotherapeutics to have the enhanced therapeutic efficacy. In the current work, we have used folic acid (FA) functionalized bovine milk-derived exosomes for oral delivery of PAC in combination with 5-fluorouracil (5-FU). Exosomes before and after the drug loading were found to have a particle size in the range of 80–100 nm, polydispersity index (PDI ~0.20), zeta potential (~−25 mV), entrapment efficiency (~82%), practical drug loading (~28%) and sustained drug release for 48 h. Significant decreases in IC₅₀ were observed in the case of exosomes loaded drugs which further improved following the FA functionalization. FA functionalized coumarin-6-loaded exosomes showed remarkably higher cellular uptake in comparison with free coumarin-6. Moreover, FA-functionalized drug-loaded exosomes showed a higher apoptotic index with better control over cell migration. Collectively, data suggested the enhanced efficacy of the combination following its loading to the folic acid functionalized exosomes against breast cancer.

Light-responsive biomaterials for ocular drug delivery

Light-responsive biomaterials can be used for the delivery of therapeutic drugs and nucleic acids, where the tunable/precise delivery of payload highlights the potential of such biomaterials for treating a variety of conditions. The translucency of eyes and advances of laser technology in ophthalmology make light-responsive delivery of drugs feasible. Importantly, light can be applied in a non-invasive fashion; therefore, light-triggered drug delivery systems have great potential for clinical impact. This review will examine various types of light-responsive polymers and the chemistry that underpins their application as ophthalmic drug delivery systems.

Biomaterials for Ophthalmic Applications

Ophthalmology is the branch of medicine that deals with diseases of the eye, the organ responsible for vision, and its attachments. Biomaterials can be made with different types of materials and can replace or improve a function or an organ, specifically the eye in the case of ophthalmic biomaterials. Biomaterials are substances that interact with biological systems for a medical purpose, either as a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a diagnostic agent, and have continued to improve over the years, leading to the creation of new biomaterials. With the arrival of new generations, biomaterials have succeeded in reducing complications and toxicity and improving biocompatibilities associated with older generations. With the aging population, eye problems are becoming more prevalent, and biomaterials have helped in recent years to improve or restore vision, improving the quality of life of many patients. This review focuses on the most clinically used ophthalmic biomaterials, including contact lenses, intraocular lenses, artificial tears, inlays and vitreous replacements. Tissue engineering is presented as a new tool that is able to be treat several ophthalmologic disorders.

Poloxamer-Based Scaffolds for Tissue Engineering Applications: A Review

Poloxamer is a triblock copolymer with amphiphilicity and reversible thermal responsiveness and has wide application prospects in biomedical applications owing to its multifunctional properties. Poloxamer hydrogels play a crucial role in the field of tissue engineering and have been regarded as injectable scaffolds for loading cells or growth factors (GFs) in the last few years. Hydrogel micelles can maintain the integrity and stability of cells and GFs and form an appropriate vascular network at the application site, thus creating an appropriate microenvironment for cell growth, nerve growth, or bone integration. The injectability and low toxicity of poloxamer hydrogels make them a noninvasive method. In addition, they can also be good candidates for bio-inks, the raw material for three-dimensional (3D) printing. However, the potential of poloxamer hydrogels has not been fully explored owing to the complex biological challenges. In this review, the latest progress and cutting-edge research of poloxamer-based scaffolds in different fields of application such as the bone, vascular, cartilage, skin, nervous system, and organs in tissue engineering and 3D printing are reviewed, and the important roles of poloxamers in tissue engineering scaffolds are discussed in depth.

Lab-on-a-Contact Lens: Recent Advances and Future Opportunities in Diagnostics and Therapeutics

The eye is one of the most complex organs in the human body, containing rich and critical physiological information (e.g., intraocular pressure, corneal temperature, and pH) as well as a library of metabolite biomarkers (e.g., glucose, proteins, and specific ions). Smart contact lenses (SCLs) can serve as a wearable intelligent ocular prosthetic device capable of noninvasive and continuous monitoring of various essential physical/biochemical parameters and drug loading/delivery for the treatment of ocular diseases. Advances in SCL technologies and the growing public interest in personalized health are accelerating SCL research more than ever before. Here, the current status and potential of SCL development through a comprehensive review from fabrication to applications to commercialization are discussed. First, the material, fabrication, and platform designs of the SCLs for the diagnostic and therapeutic applications are discussed. Then, the latest advances in diagnostic and therapeutic SCLs for clinical translation are reviewed. Later, the established techniques for wearable power transfer and wireless data transmission applied to current SCL devices are summarized. An outlook, future opportunities, and challenges for developing next-generation SCL devices are also provided. With the rise in interest of SCL development, this comprehensive and essential review can serve as a new paradigm for the SCL devices.

Construction and Evaluation of Chitosan-Based Nanoparticles for Oral Administration of Exenatide in Type 2 Diabetic Rats

Oral delivery of therapeutic peptides has been a daunting challenge due to poor transport across the tight junctions and susceptibility to enzymatic degradation in the gastrointestinal tract. Numerous advancement in nanomedicine has been made for the effective delivery of protein and peptide. Owing to the superior performance of chitosan in opening intercellular tight junctions of epithelium and excellent mucoadhesive properties, chitosan-based nanocarriers have recently garnered considerable attention, which was formulated in this paper to orally deliver the GLP-1 drug (Exenatide). Against this backdrop, we used chitosan (CS) polymers to encapsulate the exenatide, sodium tripolyphosphate (TPP) as the cross-linking agent and coated the exterior with sodium alginate (ALG) to impart the stability in an acidic environment. The chitosan/alginate nanoparticles (CS-TPP-ALG) functioned as a protective exenatide carrier, realized efficient cellular uptake and controlled release, leading to a steady hypoglycemic effect and a good oral bioavailability in vivo. Trimethyl chitosan (TMC), a chitosan derivative with stronger positive electrical properties was additionally selected as a substitute for chitosan to construct the TMC-TPP-ALG nanoparticle, and its oral peptide delivery capacity was explored in terms of both characterization and pharmacodynamics studies. Overall, our study demonstrated that functional chitosan/alginate nanoparticles can protect proteins from enzymatic degradation and enhance oral absorption, which presents important research value and application prospects.

Novel Eye Drop Delivery Systems: Advance on Formulation Design Strategies Targeting Anterior and Posterior Segments of the Eye

Eye drops are the most common and convenient route of topical administration and the first choice of treatment for many ocular diseases. However, the ocular bioavailability of traditional eye drops (i.e., solutions, suspensions, and ointments) is very low because of ophthalmic physiology and barriers, which greatly limits their therapeutic effect. Over the past few decades, many novel eye drop delivery systems, such as prodrugs, cyclodextrins, in situ gels, and nanoparticles, have been developed to improve ophthalmic bioavailability. These novel eye drop delivery systems have good biocompatibility, adhesion, and propermeation properties and have shown superior performance and efficacy over traditional eye drops. Therefore, the purpose of this review was to systematically present the research progress on novel eye drop delivery systems and provide a reference for the development of dosage form, clinical application, and commercial transformation of eye drops.

Long-Acting Protective Ocular Surface by Instilling Adhesive Dual-Antiviral Nanoparticles

The eye is susceptible to viral infections, causing severe ocular symptoms or even respiratory diseases. Methods capable of protecting the eye from external viral invasion in a long-term and highly effective way are urgently needed but have been proved to be extremely challenging. Here, a strategy of forming a long-acting protective ocular surface is described by instilling adhesive dual-antiviral nanoparticles. Taking pseudotyped severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a model virus, antiviral agent-loaded nanoparticles are coated with a "double-lock" hybrid cell membrane abundant with integrin-β1 and angiotensin converting enzyme II (ACE2). After instillation, the presence of integrin-β1 endows coated nanoparticles with steady adhesion via specific binding to Arg-Gly-Asp sequence on the fibronectin of ocular epithelium, achieving durable retention on the ocular surface. In addition to loaded inhibitors, the exposure of ACE2 can trap SARS-CoV-2 and subsequently neutralize the associated spike protein, playing a dual antiviral effect of the resulting nanoparticles. Adhesive dual-antiviral nanoparticles enabled by coating with a "double-lock" hybrid cell membrane could be a versatile platform for topical long-acting protection against viral infection of the eye.

A methacrylated hyaluronic acid network reinforced Pluronic F-127 gel for treatment of bacterial keratitis

In this study, we developed a novel in situ thermoresponsive gel by introducing crosslinked methacrylated hyaluronic acid (HA-MA) networks into Pluronic F-127 (PF-127) gel (HP gel) to achieve levofloxacin (LFX) delivery in bacterial keratitis treatment. The interactions between PF-127 and HA-MA networks were studied by scanning electron microscopy, rheology, dynamic light scattering, differential scanning calorimetry, and small angle X-ray scattering. The results showed that the HP gel exhibited a higher critical gelling temperature and lower viscosity than the PF-127 gel (P gel), and could form a uniform thin layer on the ocular surface. Moreover, the drug release profile and gel dissolution rate revealed that the HA-MA network could retard the diffusion and dissolution of drug molecules and prolong the drug release time, which corresponded to an enhanced antibacterial ability of the HP-LFX gel. Furthermore, the HP gel exhibited low cytotoxicity to human corneal epithelial cells (HCECs). Finally, an in vivo pharmacodynamic study was conducted with rabbit keratitis models. An improved treatment efficacy was observed after application of the HP-LFX gels. This study highlights the potential of HP gels in ophthalmic drug delivery.

Sustained Release In Situ Thermogelling Hydrogel of Cerebrolysin for Treatment of Facial Nerve Axotomy in Rats

PURPOSE

The most essential principle in managing facial nerve (FN) injury is proper diagnosis and early treatment. This study evaluated local application of different concentrations and injection intervals of Cerebrolysin hydrogel (CBLH) for facial nerve axotomy (FNA) treatment. We hypothesized that local application of CBLH may provide a sustained release of Cerebrolysin and enhance neural regeneration.

METHODS

The authors implemented a randomized, controlled, blinded animal study. The sample was composed of the right FN. Functionally, eye-blink reflex was evaluated 2 and 4 weeks postoperatively. All rats were euthanized after 4 weeks, and nerve regeneration was evaluated histopathologically and immunohistochemically (IHC) with antibody against neurofilament (anti-NF) and S100 proteins. Descriptive and correlation statistics were computed, and the P value was set at .05.

RESULTS

The sample was composed of 72 adult male rats equally allocated into 8 groups. Groups I and V served as control groups and were injected with phosphate buffered saline once and four times, respectively. Rest of the groups were injected with 5%, 10%, and 15% CBLH once in groups II, III, IV and weekly in groups VI, VII, and VIII. CBLH showed statistically significant FN regeneration by enhancing Schwann and axonal growth compared to control group especially with single injection of 10%, 15%, and 5% 4-time injections, where the P value was less than .001. Significant improvement of eye-blink reflex was correlated with structural improvement associated with CBLH.

CONCLUSION

Finally, CBLH enhanced nerve regeneration and rehabilitation after FNA in rats. Therefore, it could be considered as an alternative treatment of FNA. More experimental and clinical trials should be considered to detect the effectiveness of CBLH in neural regeneration.

Preparation of NLCs-Based Topical Erythromycin Gel: In Vitro Characterization and Antibacterial Assessment

In the present study, erythromycin (EM)-loaded nanostructured lipid carriers (NLCs) were prepared by the emulsification and ultra-sonication method. EM-NLCs were optimized by central composite design using the lipid (A), pluronic F127 (B) and sonication time (C) as independent variables. Their effects were evaluated on particle size (Y₁) and entrapment efficiency (Y₂). The optimized formulation (EM-NLCs-opt) showed a particle size of 169.6 ± 4.8 nm and entrapment efficiency of 81.7 ± 1.4%. EM-NLCs-opt further transformed into an in-situ gel system by using the carbopol 940 and chitosan blend as a gelling agent. The optimized EM-NLCs in situ gel (EM-NLCs-opt-IG4) showed quick gelation and were found to be stable for more than 24 h. EM-NLCs-opt-IG4 showed prolonged drug release compared to EM in situ gel. It also revealed significant high permeation (56.72%) and flux (1.51-fold) than EM in situ gel. The irritation and hydration study results depicted no damage to the goat cornea. HET-CAM results also confirmed its non-irritant potential (zero score). EM-NLCs-opt-IG4 was found to be isotonic and also showed significantly (p < 0.05) higher antimicrobial activity than EM in situ gel. The findings of the study concluded that NLCs laden in situ gel is an alternative delivery of erythromycin for the treatment of bacterial conjunctivitis.

Cellulose nanocrystals: Fundamentals and biomedical applications

The present review explores the recent developments of cellulose nanocrystals, a class of captivating nanomaterials in variety of applications. CNCs are made by acid hydrolysing cellulosic materials like wood, cotton, tunicate, flax fibers by sonochemistry. It has many desirable properties, including a high tensile strength, wide surface area, stiffness, exceptional colloidal stability, and the ability to be modified. CNCs are colloidally stable, hydrophilic, and rigid rod-shaped bio-based nanomaterials in the form of rigid rods with high strength and surface area that has a diverse set of applications and properties. The intriguing features emerging from numerous fibers studies, such as renewable character and biodegradability, piqued the curiosity of many researchers who worked on lowering the size of these fibers. Physicochemical properties such as rheological, mechanical, thermal, lipid crystalline, swelling capacity, microstructural properties result in affecting surface-area to volume ratio and crystallinity of cellulose nanocrystals. The present article highlights the fundamentals of cellulose nanocrystals such as sources, isolation, fabrication, properties and surface modification with an emphasis on plethora of biomedical applications. Selected nanocellulose studies with significant findings on cellular labelling and bioimaging, tissue engineering, biosensors, gene delivery, anti-viral property, anti-bacterial property, ocular delivery, modified drug release, anti-cancer activity and enzyme immobilization are emphasized.

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.

Enhanced topical corticosteroids delivery to the eye: A trade-off in strategy choice

Topical corticosteroids are the primary treatment of ocular inflammation caused by surgery, injury, or other conditions. Drug pre-corneal residence time, drug water solubility, and drug corneal permeability coefficient are the major factors that determine the ocular drug bioavailability after topical administration. Although growing research successfully enhanced local delivery of corticosteroids utilizing various strategies, rational and dynamic approaches to strategy selection are still lacking. Within this review, an overview of the various strategies as well as their performance in retention, solubility, and permeability coefficient of corticosteroids are provided. On this basis, the tradeoff of strategy selection is discussed, which may shed light on the rational choice and application of ophthalmic delivery enhancement strategies.

Balance of Drug Residence and Diffusion in Lacrimal Fluid Determine Ocular Bioavailability in In Situ Gels Incorporating Tranilast Nanoparticles

We previously designed ophthalmic formulations (nTRA) containing tranilast nanoparticles (Tra-NPs) with high uptake into ocular tissues. In this study, we used in situ gel (ISG) bases comprising combinations of pluronic F127 (F127) and methylcellulose (MC/F127), pluronic F68 (F68/F127), and Carbopol (Car/F127), and we developed in situ gels incorporating Tra-NPs (Tra-NP-incorporated ISNGs) such as nTRA-F127, nTRA-MC/F127, nTRA-F68/F127, and nTRA-Car/F127. Moreover, we demonstrated the therapeutic effect on conjunctival inflammation using lipopolysaccharide-induced rats. Each Tra-NP-incorporated ISNG was prepared by the bead mill method, the particle size was 40–190 nm, and the tranilast release and diffusion from formulation were nTRA > nTRA-F127 > nTRA-F68/F127 > nTRA-Car/F127 > nTRA-MC/F127. In the Tra-NP-incorporated ISNGs, the tranilast residence time in the lacrimal fluid, cornea, and conjunctiva was prolonged, although the C_max was attenuated in comparison with nTRA. On the other hand, no significant difference in conjunctival inflammation between non- and nTRA-F127-instilled rats was found; however, the nTRA-F68/F127, nTRA-Car/F127, and nTRA-MC/F127 (combination-ISG) attenuated the vessel leakage, nitric oxide, and tumor necrosis factor-α expression. In particular, nTRA-F68/F127 was significant in preventing the conjunctival inflammation. In conclusion, we found that the combination-ISG base prolonged the residence time of Tra-NPs; however, Tra-NP release from the formulation was attenuated, and the T_max was delayed longer than that in nTRA. The balance of drug residence and diffusion in lacrimal fluid may be important in providing high ocular bioavailability in formulations containing solid nanoparticles.

Repurposing of nifedipine loaded in situ ophthalmic gel as a novel approach for glaucoma treatment

Glaucoma is a chronic eye disease characterized by elevated intraocular pressure (IOP) which causes severe complications to the eyes and may lead to vision loss. The effective treatment of such diseases motivated the search for novel and unique drugs and delivery systems. It has been reported that, nifedipine (NF) is effective in reducing the elevated IOP due to vasodilatation of eye vascular smooth muscles. NF loaded thermo-sensitive in situ gels were prepared by the cold method using poloxamer 407 (P407) and hydroxypropyl methyl cellulose (HPMC) polymers adopting Box-Behnken experimental design. All the prepared formulae were tested for homogeneity, clarity, pH, isotonicity, gelling capacity, rheological behavior, in vitro drug release and were tested in vivo on rabbits. The prepared in situ gels were homogenous, transparent, having a pH ranged from 5 to 5.5 and undergo sol-gel transition within few seconds physiological temperature. The in situ gels showed sustained in vitro release of NF where about 76% of the loaded drug was released over 12 h. NF loaded in situ gels showed a 45.83 ± 2.91% reduction in the IOP, with no sign of toxicity or irritation to the eye in rabbits. The current investigations clarified the efficiency of this novel and unique NF loaded in situ gel for the control of the IOP compared to the conventional ophthalmic dosage forms.

Vildagliptin plasticized hydrogel film in the control of ocular inflammation after topical application: study of hydration and erosion behaviour

Vildagliptin (VID) is a dipeptidyl peptidase-4 (DPP-4) inhibitor used in controlling blood glucose level in type 2 diabetes. Vildagliptin improves beta cells function and is also suggested to effectively control the inflammation. The possible ocular anti-inflammatory property of vildagliptin has been explored using topically applied plasticized ocular film formulation. Film formulation was prepared by solvent cast and evaporation method using triethanolamine (TEA), dimethyl sulphoxide (DMSO), and polyethylene glycol 400 (PEG 400) as the plasticizer in HPMC hydrogel matrix base. Anti-inflammatory study was carried out in the carrageenan induced ocular rabbit model. Analytical methods confirmed that the drug was present almost in completely amorphized form in the film formulation. Level of hydration, swelling and erosion rate of the film played the controlling factor in the process of drug release, ocular residence and permeation. Maximum swelling rate of 363 h−1 has been shown by VHT compared to other formulation of VHD and VHP (174 and 242 h−1 respectively). Film containing DMSO exhibited highest in vitro release as well as ex vivo ocular permeation. Film formulation has shown a fast recovery of ocular inflammation in contrast to the untreated eye after inducing inflammation. Plasticized vildagliptin hydrogel film formulation could be utilized in the management and control of ocular inflammation particularly with diabetic retinopathy after proper clinical studies in higher animal and human individuals.

Mucoadhesive properties of nanogels based on stimuli-sensitive glycosaminoglycan-graft-pNIPAAm copolymers

Mucoadhesive formulations capable of situ gelation are promising for improving ocular drug delivery. Here we investigated two types of nanogels based on anionic glycosaminoglycans with grafted thermo-responsive poly(N-isopropylacrylamide) chains. One type of nanogels were formed by thermo-induced gelling of heparin-graft-poly(N-isopropylacrylamide) and chondroitin sulfate-graft-poly(N-isopropylacrylamide) copolymers. Another type of nanogels was based on the same copolymers, but terminal groups of thermosensitive macromolecular chains were modified to form covalent disulfide cross-links. All types of nanogels were studied towards their ability to encapsulate and release model drug - dexamethasone. Mucoadhesivity of both thermo-gelled and covalently cross-linked polymeric systems, as well as their ability to interact with dexamethasone, was assessed by microscale thermophoresis (MST). Mucoadhesion properties were also evaluated by isothermal titration calorimetry (ITC), which were in good correlation with MST data. The presence of disulfide linkages and thiol groups were shown to favor improved binding of cross-linked nanogels to mucin. Moreover, in vivo intraocular pressure studies showed that presence of polymers in solution can alter the ocular absorption of carbonic anhydrase inhibitor from eyedrops. The pharmacological effect was in line with mucoadhesive properties of these copolymers.

Studying the ophthalmic toxicity potential of developed ketoconazole loaded nanoemulsion in situ gel formulation for ophthalmic administration

Ocular fungal infections are one of the essential reasons for vision loss, especially in developing countries for tropical regions. Ketoconazole (KZ), a broad-spectrum antifungal drug, is a lipophilic compound and practically insoluble in water. Since topical ophthalmic drug delivery confronts low bioavailability, an in situ gel formulation is designed to improve the residence time and consequently the bioavailability. Safety of the developed formulation as a carrier for ophthalmic drug delivery was measured using three different methods: MTT assay for measuring cell viability in which the human retinal pigmentation epithelial cells (RPE) were used, HET-CAM as a borderline method between in vivo and in vitro techniques for investigating the irritation potential of the chosen formulation which was done by adding formulation directly on the CAM surface and visually monitoring the vessels in terms of irritation reactions, and finally the modified Draize test for evaluating tolerability of the selected formulation on eyes. According to our results from the MTT test, cell viability for KZ-NE in situ gel formulation at 0.1% concentration was acceptable. The results obtained from the HET-CAM investigation didn't show any sign of vessel injury on the CAM surface for prepared formulation. Additionally, during 24 hours, the developed formulation was tolerable by rabbit eyes. Regarding our results, KZ-NE in situ gel formulation was non-irritant and non-toxic and can be well-tolerated and presented as an applicable vehicle for ophthalmic delivery of the anti-fungal drug.

Intellective and stimuli-responsive drug delivery systems in eyes

Stimuli-responsive drug delivery systems have attracted widespread attention in recent years since they can control drug release in a spatiotemporal manner and can achieve tunable drug release according to patient's physiological or pathological condition. In this review, we briefly introduce the drug delivery barriers and drug delivery systems in the anterior and posterior segment of eyes, and collect the recent advances in stimuli-responsive drug delivery systems in eyes for controlled drug release in response to exogenous stimuli (ultrasound, magnetic stimulus, electrical stimulus, and light) or endogenous stimuli (enzyme, active oxygen species, temperature, ions, and pH). In addition, the design and mechanisms of the stimuli-responsive drug delivery systems have been summarized in this review, and the advantages and limitations are also briefly discussed.

Ocular toxicity assessment of nanoemulsion in-situ gel formulation of fluconazole

PURPOSE

Fluconazole is an effective anti-fungal drug. Due to the limitations of fluconazole, such as poor water solubility and consequently low ocular bioavailability, an optimized fluconazole nanoemulsion in-situ gel formulation (temperature-sensitive) was developed.

METHODS AND MATERIALS

To verify formulation's safety for ophthalmic use, preparation was tested for potential ocular toxicity using a cell viability assay on retinal cells. The hen's egg test-chorioallantoic membrane (HET-CAM), as a borderline test between in vivo and in vitro techniques, was chosen for investigating the irritation potential of the formulation. HET-CAM test was done by adding the formulation directly to the CAM surface and monitoring the vessels visually in terms of irritation reactions. Eye tolerance was determined using the modified Draize test.

RESULTS

Viability assay on retinal cells displayed that fluconazole nanoemulsion in-situ gel formulation was non-toxic and can be safely used in the eye at concentrations of 0.1% and 0.5%. HET-CAM and Draize tests revealed that optimized formulation of fluconazole did not result in any irritation and was considered non-irritant and well-tolerated for ocular use.

CONCLUSION

Regarding to the findings of the three mentioned methods, fluconazole nanoemulsion in-situ gel formulation is harmless and as a proper and safe alternative, can be considered for ocular delivery of fluconazole in the future.

In vivo and in vitro Evaluation of in situ Gel Formulation of Pemirolast Potassium in Allergic Conjunctivitis

Background

To establish a novel delivery system of pemirolast potassium-loaded gellan gum in situ gel in allergic conjunctivitis therapy.

Methods

The prepared in situ gels were studied in the following aspects: in vitro gelation, in vitro release, stability, viscosity measurement, in vivo tear kinetics and pharmacodynamics.

Results

In this study, the results showed that the viscosity of the in situ gels significantly increased when the preparation was in contact with simulated tear fluid and it also exhibited good stability in a period of three months. In vitro release showed that the release of pemirolast potassium from in situ gels had a good sustained release ability. No ocular damage or abnormal clinical signs to the cornea, iris, or conjunctivae were visible. Consistent with the in vitro studies, pemirolast potassium in situ gels were highly efficient in suppressing the inflammatory symptoms and improving the ocular bioavailability.

Conclusion

Pemirolast potassium ocular in situ gels are safe and promising therapeutic alternatives to the existing medications for allergic conjunctivitis therapy.