Formulations for Intranasal Delivery of Pharmacological Agents to Combat Brain Disease: A New Opportunity to Tackle GBM?

Comprehensive insights into glioblastoma multiforme: drug delivery challenges and multimodal treatment strategies

Glioblastoma multiforme (GBM) is one of the most common and malignant brain tumors, with a high prevalence in elderly population. Most chemotherapeutic agents fail to reach the tumor site due to various challenges. However, smart nanocarriers have demonstrated excellent drug-loading capabilities, enabling them to cross the blood brain tumor barrier for the GBM treatment. Surface modification of nanocarriers has significantly enhanced their potential for targeting therapeutics. Moreover, recent innovations in drug therapies, such as the incorporation of theranostic agents in nanocarriers and antibody-drug conjugates, have offered newer insights for both diagnosis and treatment. This review focuses on recent advances in new therapeutic interventions for GBM, with an emphasis on the nanotheranostics systems to maximize therapeutic and diagnostic outcomes.

Exploring intranasal drug delivery via nanocarriers: A promising glioblastoma therapy

Glioblastoma is one of the most recurring types of glioma, having the highest mortality rate among all other gliomas. Traditionally, the standard course of treatment for glioblastoma involved maximum surgical resection, followed by chemotherapy and radiation therapy. Nanocarriers have recently focused on enhancing the chemotherapeutic administration to the brain to satisfy unmet therapeutic requirements for treating brain-related disorders. Due to the significant drawbacks and high recurrence rates of gliomas, intranasal administration of nanocarrier systems presents several advantages. These include low toxicity, non-invasiveness, and the ability to cross the blood-brain barrier. By customizing their size, encasing them with mucoadhesive agents, or undergoing surface modification that encourages movement over the nose's mucosa, we can exceptionally engineer nanocarriers for intranasal administration. Olfactory and trigeminal nerves absorb drugs administered nasally and transport them to the brain, serving as the primary delivery mechanism for nose-to-brain administration. This review sums up the latest developments in chemotherapeutic nanocarriers, such as metallic nanoparticles, polymeric nanoparticles, nanogels, nano vesicular carriers, genetic material-based nanocarriers, and polymeric micelles. These nanocarriers have demonstrated efficient drug delivery from the nose to the brain, effectively overcoming mucociliary clearance. However, challenges persist, such as limitations in targeted chemotherapy and restricted drug loading capacity for intranasal administration. Additionally, the review addresses regulatory considerations and prospects for these innovative drug delivery systems.

Laronidase-loaded liposomes reach the brain and other hard-to-treat organs after noninvasive nasal administration

Mucopolysaccharidosis type I (MPS I) is caused by a lack of the lysosomal enzyme α-L-iduronidase (IDUA), responsible for the degradation of the glycosaminoglycans (GAGs) dermatan and heparan sulfate, leading to multisystemic signs and symptoms. Enzyme replacement therapy (ERT) is a treatment that consists of weekly intravenous administrations of laronidase, a recombinant version of IDUA. However, ERT has limited access to certain tissues, such as bone, cartilage, and brain, and laronidase fails to trespass the BBB. In this sense, this study reports the development and characterization of laronidase-loaded liposomes for the treatment of MPS I mice. Liposomal complexes were obtained by the thin film formation method followed by microfluidization. The main characterization results showed mean vesicle size of 103.0 ± 3.3 nm, monodisperse populations of vesicles, zeta potential around + 30.0 ± 2.1 mV, and mucoadhesion strength of 5.69 ± 0.14 mN. Treatment of MPS I mice fibroblasts showed significant increase in enzyme activity. Nasal administration of complexes to MPS I mice resulted in significant increase in laronidase activity in the brain cortex, heart, lungs, kidneys, eyes, and serum. The overall results demonstrate the feasibility of nasal administration of laronidase-loaded liposomes to deliver enzyme in difficult-to-reach tissues, circumventing ERT issues and bringing hope as a potential treatment for MPS I.

Navigating the Nose-to-Brain Route: A Systematic Review on Lipid-Based Nanocarriers for Central Nervous System Disorders

Background: The blood–brain barrier (BBB) regulates brain substance entry, posing challenges for treating brain diseases. Traditional methods face limitations, leading to the exploration of non-invasive intranasal drug delivery. This approach exploits the direct nose-to-brain connection, overcoming BBB restrictions. Intranasal delivery enhances drug bioavailability, reduces dosage, and minimizes systemic side effects. Notably, lipid nanoparticles, such as solid lipid nanoparticles and nanostructured lipid carriers, offer advantages like improved stability and controlled release. Their nanoscale size facilitates efficient drug loading, enhancing solubility and bioavailability. Tailored lipid compositions enable optimal drug release, which is crucial for chronic brain diseases. This review assesses lipid nanoparticles in treating neuro-oncological and neurodegenerative conditions, providing insights for effective nose-to-brain drug delivery. Methods: A systematic search was conducted across major medical databases (PubMed, Ovid MEDLINE, and Scopus) up to 6 January 2024. The search strategy utilized relevant Medical Subject Heading (MeSH) terms and keywords related to “lipid nanoparticles”, “intranasal administration”, “neuro-oncological diseases”, and “neurodegenerative disorders”. This review consists of studies in vitro, in vivo, or ex vivo on the intranasal administration of lipid-based nanocarriers for the treatment of brain diseases. Results: Out of the initial 891 papers identified, 26 articles met the eligibility criteria after a rigorous analysis. The exclusion of 360 articles was due to reasons such as irrelevance, non-reporting selected outcomes, the article being a systematic literature review or meta-analysis, and lack of method/results details. This systematic literature review, focusing on nose-to-brain drug delivery via lipid-based nanocarriers for neuro-oncological, neurodegenerative, and other brain diseases, encompassed 60 studies. A temporal distribution analysis indicated a peak in research interest between 2018 and 2020 (28.3%), with a steady increase over time. Regarding drug categories, Alzheimer’s disease was prominent (26.7%), followed by antiblastic drugs (25.0%). Among the 65 drugs investigated, Rivastigmine, Doxorubicin, and Carmustine were the most studied (5.0%), showcasing a diverse approach to neurological disorders. Notably, solid lipid nanoparticles (SLNs) were predominant (65.0%), followed by nanostructured lipid carriers (NLCs) (28.3%), highlighting their efficacy in intranasal drug delivery. Various lipids were employed, with glyceryl monostearate being prominent (20.0%), indicating preferences in formulation. Performance assessment assays were balanced, with in vivo studies taking precedence (43.3%), emphasizing the translation of findings to complex biological systems for potential clinical applications. Conclusions: This systematic review reveals the transformative potential of intranasal lipid nanoparticles in treating brain diseases, overcoming the BBB. Positive outcomes highlight the effectiveness of SLNs and NLCs, which are promising new approaches for ailments from AD to stroke and gliomas. While celebrating progress, addressing challenges like nanoparticle toxicity is also crucial.

Visualization of nasal powder distribution using biomimetic human nasal cavity model

Nasal drug delivery efficiency is highly dependent on the position in which the drug is deposited in the nasal cavity. However, no reliable method is currently available to assess its impact on delivery performance. In this study, a biomimetic nasal model based on three-dimensional (3D) reconstruction and three-dimensional printing (3DP) technology was developed for visualizing the deposition of drug powders in the nasal cavity. The results showed significant differences in cavity area and volume and powder distribution in the anterior part of the biomimetic nasal model of Chinese males and females. The nasal cavity model was modified with dimethicone and validated to be suitable for the deposition test. The experimental device produced the most satisfactory results with five spray times. Furthermore, particle sizes and spray angles were found to significantly affect the experimental device's performance and alter drug distribution, respectively. Additionally, mometasone furoate (MF) nasal spray (NS) distribution patterns were investigated in a goat nasal cavity model and three male goat noses, confirming the in vitro and in vivo correlation. In conclusion, the developed human nasal structure biomimetic device has the potential to be a valuable tool for assessing nasal drug delivery system deposition and distribution.

Lamotrigine-Loaded Poloxamer-Based Thermo-Responsive Sol-Gel: Formulation, In Vitro Assessment, Ex Vivo Permeation, and Toxicology Study

The present study aimed to prepare, characterize, and evaluate a thermo-responsive sol-gel for intranasal delivery of lamotrigine (LTG), which was designed for sustained drug delivery to treat epilepsy. LTG sol-gel was prepared using the cold method by changing the concentrations of poloxamer 407 and poloxamer 188, which were used as thermo-reversible polymers. The optimized formulations of sol-gel were analyzed for clarity, pH, viscosity, gelation temperature, gelation time, spreadability, drug content, in vitro drug release studies, ex vivo permeation studies, and in vivo toxicological studies. FTIR, XRD, and DSC were performed to determine the thermal stability of the drug and polymers. The prepared formulations had a clear appearance in sol form; they were liquid at room temperature and became gel at temperatures between 31 °C and 36 °C. The pH was within the range of the nasal pH, between 6.2 and 6.4. The drug content was found to be between 92% and 94%. In vitro drug release studies indicated that the formulations released up to 92% of the drug within 24 h. The FTIR, DSC, and XRD analyses showed no interaction between the drug and the polymer. A short-term stability study indicated that the formulation was stable at room temperature and at 4-8 °C. There was a slight increase in viscosity at room temperature, which may be due to the evaporation of the vehicle. A histological study indicated that there were no signs of toxicity seen in vital organs, such as the brain, kidney, liver, heart, and spleen. It can be concluded from the above results that the prepared intranasal sol-gel for the delivery of LTG is safe for direct nose-to-brain delivery to overcome the first-pass effect and thus enhance bioavailability. It can be considered an effective alternative to conventional drug delivery for the treatment of epilepsy.

Peptide-Based Agents for Cancer Treatment: Current Applications and Future Directions

Peptide-based strategies have received an enormous amount of attention because of their specificity and applicability. Their specificity and tumor-targeting ability are applied to diagnosis and treatment for cancer patients. In this review, we will summarize recent advancements and future perspectives on peptide-based strategies for cancer treatment. The literature search was conducted to identify relevant articles for peptide-based strategies for cancer treatment. It was performed using PubMed for articles in English until June 2023. Information on clinical trials was also obtained from ClinicalTrial.gov. Given that peptide-based strategies have several advantages such as targeted delivery to the diseased area, personalized designs, relatively small sizes, and simple production process, bioactive peptides having anti-cancer activities (anti-cancer peptides or ACPs) have been tested in pre-clinical settings and clinical trials. The capability of peptides for tumor targeting is essentially useful for peptide-drug conjugates (PDCs), diagnosis, and image-guided surgery. Immunomodulation with peptide vaccines has been extensively tested in clinical trials. Despite such advantages, FDA-approved peptide agents for solid cancer are still limited. This review will provide a detailed overview of current approaches, design strategies, routes of administration, and new technological advancements. We will highlight the success and limitations of peptide-based therapies for cancer treatment.

Paclitaxel Delivery to the Brain for Glioblastoma Treatment

The development of paclitaxel-loaded polymeric nanoparticles for the treatment of brain tumors was investigated. Poly(lactide-glycolide) (PLGA) nanoparticles containing 10% w/w paclitaxel with a particle size of 216 nm were administered through intranasal and intravenous routes to male Sprague-Dawley rats at a dose of 5 mg/kg. Both routes of administration showed appreciable accumulation of paclitaxel in brain tissue, liver, and kidney without any sign of toxicity. The anti-proliferative effect of the nanoparticles on glioblastoma tumor cells was comparable to that of free paclitaxel.

Nose-to-brain drug delivery for the treatment of CNS disease: New development and strategies

Delivering drugs to the brain has always been a challenging task due to the restrictive properties of the blood-brain barrier (BBB). Intranasal delivery is therefore emerging as an efficient method of administration, making it easy to self-administration and thus provides a non-invasive and painless alternative to oral and parenteral administration for delivering therapeutics to the central nervous system (CNS). Recently, drug formulations have been developed to further enhance this nose-to-brain transport, primarily using nanoparticles (NPs). Therefore, the purposes of this review are to highlight and describe the anatomical basis of nasal-brain pathway and provide an overview of drug formulations and current drugs for intranasal administration in CNS disease.

Challenges in the Development and Application of Organ-on-Chips for Intranasal Drug Delivery Studies

With the growing demand for the development of intranasal (IN) products, such as nasal vaccines, which has been especially highlighted during the COVID-19 pandemic, the lack of novel technologies to accurately test the safety and effectiveness of IN products in vitro so that they can be delivered promptly to the market is critically acknowledged. There have been attempts to manufacture anatomically relevant 3D replicas of the human nasal cavity for in vitro IN drug tests, and a couple of organ-on-chip (OoC) models, which mimic some key features of the nasal mucosa, have been proposed. However, these models are still in their infancy, and have not completely recapitulated the critical characteristics of the human nasal mucosa, including its biological interactions with other organs, to provide a reliable platform for preclinical IN drug tests. While the promising potential of OoCs for drug testing and development is being extensively investigated in recent research, the applicability of this technology for IN drug tests has barely been explored. This review aims to highlight the importance of using OoC models for in vitro IN drug tests and their potential applications in IN drug development by covering the background information on the wide usage of IN drugs and their common side effects where some classical examples of each area are pointed out. Specifically, this review focuses on the major challenges of developing advanced OoC technology and discusses the need to mimic the physiological and anatomical features of the nasal cavity and nasal mucosa, the performance of relevant drug safety assays, as well as the fabrication and operational aspects, with the ultimate goal to highlight the much-needed consensus, to converge the effort of the research community in this area of work.

Long-Acting Therapeutic Delivery Systems for the Treatment of Gliomas

Despite the emergence of cutting-edge therapeutic strategies and tremendous progress in research, a complete cure of glioma remains elusive. The heterogenous nature of tumor, immunosuppressive state and presence of blood brain barrier are few of the major obstacles in this regard. Long-acting depot formulations such as injectables and implantables are gaining attention for drug delivery to brain owing to their ease in administration and ability to elute drug locally for extended durations in a controlled manner with minimal toxicity. Hybrid matrices fabricated by incorporating nanoparticulates within such systems help to enhance pharmaceutical advantages. Utilization of long-acting depots as monotherapy or in conjunction with existing strategies rendered significant survival benefits in many preclinical studies and some clinical trials. The discovery of novel targets, immunotherapeutic strategies and alternative drug administration routes are now coupled with several long-acting systems with an ultimate aim to enhance patient survival and prevent glioma recurrences.

Nanocomposite formulation for a sustained release of free drug and drug-loaded responsive nanoparticles: an approach for a local therapy of glioblastoma multiforme

Malignant gliomas are a type of primary brain tumour that originates in glial cells. Among them, glioblastoma multiforme (GBM) is the most common and the most aggressive brain tumour in adults, classified as grade IV by the World Health Organization. The standard care for GBM, known as the Stupp protocol includes surgical resection followed by oral chemotherapy with temozolomide (TMZ). This treatment option provides a median survival prognosis of only 16-18 months to patients mainly due to tumour recurrence. Therefore, enhanced treatment options are urgently needed for this disease. Here we show the development, characterization, and in vitro and in vivo evaluation of a new composite material for local therapy of GBM post-surgery. We developed responsive nanoparticles that were loaded with paclitaxel (PTX), and that showed penetration in 3D spheroids and cell internalization. These nanoparticles were found to be cytotoxic in 2D (U-87 cells) and 3D (U-87 spheroids) models of GBM. The incorporation of these nanoparticles into a hydrogel facilitates their sustained release in time. Moreover, the formulation of this hydrogel containing PTX-loaded responsive nanoparticles and free TMZ was able to delay tumour recurrence in vivo after resection surgery. Therefore, our formulation represents a promising approach to develop combined local therapies against GBM using injectable hydrogels containing nanoparticles.

Nasal administration of a temozolomide-loaded thermoresponsive nanoemulsion reduces tumor growth in a preclinical glioblastoma model

Glioblastoma (GB) is the worst and most common primary brain tumor. Temozolomide (TMZ), an alkylating agent, is widely used for treating primary and recurrent high-grade gliomas. However, at least 50% of TMZ treated patients do not respond to TMZ and the development of chemoresistance is a major problem. Here, we designed a lipid nanoemulsion containing a thermoresponsive polymer (poloxamer 407) aiming to improve TMZ release into the brain via nasal delivery. Increasing amounts of poloxamer 407 were added to preformed nanoemulsions (250 nm-range) obtained by spontaneous emulsification. The influence of the polymer concentration (from 2.5% to 12.5%) and temperature on viscosity was clearly evidenced. Such effect was also noticed on the mucoadhesiveness of formulations, as well as TMZ release rate and retention/permeation through nasal porcine mucosa using Franz-type diffusion cells. From these results, a formulation containing 10% of poloxamer (NTMZ-P10) was selected for further experiments by nasal route. A significantly higher TMZ amount was observed in the brain of rats from NTMZ-P10 in comparison with controls. Finally, our results show that formulation reduced significantly tumor growth by three-fold: 103.88 ± 43.67 mm³ (for NTMZ-P10) and 303.28 ± 95.27 mm³ (control). Overall, these results suggest the potential of the thermoresponsive formulation, administered by the non-invasive nasal route, as a future effective glioblastoma treatment.

Focused Delivery of Chemotherapy to Augment Surgical Management of Brain Tumors

Chemotherapy as an adjuvant therapy that has largely failed to significantly improve outcomes for aggressive brain tumors; some reasons include a weak blood brain barrier penetration and tumor heterogeneity. Recently, there has been interest in designing effective ways to deliver chemotherapy to the tumor. In this review, we discuss the mechanisms of focused chemotherapies that are currently under investigation. Nanoparticle delivery demonstrates both a superior permeability and retention. However, thus far, it has not demonstrated a therapeutic efficacy for brain tumors. Convection-enhanced delivery is an invasive, yet versatile method, which appears to have the greatest potential. Other vehicles, such as angiopep-2 decorated gold nanoparticles, polyamidoamine dendrimers, and lipid nanostructures have demonstrated efficacy through sustained release of focused chemotherapy and have either improved cell death or survival in humans or animal models. Finally, focused ultrasound is a safe and effective way to disrupt the blood brain barrier and augment other delivery methods. Clinical trials are currently underway to study the safety and efficacy of these methods in combination with standard of care.

The barrier and interface mechanisms of the brain barrier, and brain drug delivery

Three different barriers are formed between the cerebrovascular and the brain parenchyma: the blood-brain barrier (BBB), the blood-cerebrospinal fluid barrier (BCSFB), and the cerebrospinal fluid-brain barrier (CBB). The BBB is the main regulator of blood and central nervous system (CNS) material exchange. The semipermeable nature of the BBB limits the passage of larger molecules and hydrophilic small molecules, Food and Drug Administration (FDA)-approved drugs for the CNS have been generally limited to lipid-soluble small molecules. Although the complexity of the BBB affects CNS drug delivery, understanding the composition and function of the BBB can provide a platform for the development of new methods for CNS drug delivery. This review summarizes the classification of the brain barrier, the composition and role of the basic structures of the BBB, and the transport, barrier, and destruction mechanisms of the BBB; discusses the advantages and disadvantages of different drug delivery methods and prospects for future drug delivery strategies.

Brain targeted delivery of carmustine using chitosan coated nanoparticles via nasal route for glioblastoma treatment

This study aims to develop chitosan-coated PLGA nanoparticles intended for nose-to-brain delivery of carmustine. Formulations were prepared by the double emulsion solvent evaporation method and optimized by using Box-Behnken Design. The optimized nanoparticles were obtained to satisfactory levels in terms of particle size, PDI, entrapment efficiency, and drug loading. In vitro drug release and ex-vivo permeation showed sustained release and enhanced permeability (approx. 2 fold) of carmustine compared to drug suspension. The AUC_0-t of brain obtained with carmustine-loaded nanoparticles via nasal administration in Albino Wistar rats was 2.8 and 14.7 times that of intranasal carmustine suspension and intravenous carmustine, respectively. The MTT assay on U87 MG cell line showed a significant decrease (P < 0.05) in the IC50 value of the formulation (71.23 μg ml^-1) as compared to drug suspension (90.02 μg ml^-1).These findings suggest chitosan coated nanoparticles could be used to deliver carmustine via intranasal administration to treat Glioblastoma multiforme.

Biopolymer Nanoparticles for Nose-to-Brain Drug Delivery: A New Promising Approach for the Treatment of Neurological Diseases

Diseases affecting the central nervous system (CNS) are among the most disabling and the most difficult to cure due to the presence of the blood-brain barrier (BBB) which represents an impediment from a therapeutic and diagnostic point of view as it limits the entry of most drugs. The use of biocompatible polymer nanoparticles (NPs) as vehicles for targeted drug delivery to the brain arouses increasing interest. However, the route of administration of these vectors remains critical as the drug must be delivered without being degraded to achieve a therapeutic effect. An innovative approach for the administration of drugs to the brain using polymeric carriers is represented by the nose-to-brain (NtB) route which involves the administration of the therapeutic molecule through the neuro-olfactory epithelium of the nasal mucosa. Nasal administration is a non-invasive approach that allows the rapid transport of the drug directly to the brain and minimizes its systemic exposure. To date, many studies involve the use of polymer NPs for the NtB transport of drugs to the brain for the treatment of a whole series of disabling neurological diseases for which, as of today, there is no cure. In this review, various types of biodegradable polymer NPs for drug delivery to the brain through the NtB route are discussed and particular attention is devoted to the treatment of neurological diseases such as Glioblastoma and neurodegenerative diseases.

Intranasal Delivery of Functionalized Polymeric Nanomaterials to the Brain

Intravenous delivery of nanomaterials containing therapeutic agents and various cargos for treating neurological disorders is often constrained by low delivery efficacy due to difficulties in passing the blood-brain barrier (BBB). Nanoparticles (NPs) administered intranasally can move along olfactory and trigeminal nerves so that they do not need to pass through the BBB, allowing non-invasive, direct access to selective neural pathways within the brain. Hence, intranasal (IN) administration of NPs can effectively deliver drugs and genes into targeted regions of the brain, holding potential for efficacious disease treatment in the central nervous system (CNS). In this review, current methods for delivering conjugated NPs to the brain are primarily discussed. Distinctive potential mechanisms of therapeutic nanocomposites delivered via IN pathways to the brain are then discussed. Recent progress in developing functional NPs for applications in multimodal bioimaging, drug delivery, diagnostics, and therapeutics is also reviewed. This review is then concluded by discussing existing challenges, new directions, and future perspectives in IN delivery of nanomaterials.

Lipid-Based Nanocarriers for Neurological Disorders: A Review of the State-of-the-Art and Therapeutic Success to Date

Neurodegenerative disorders including Alzheimer's, Parkinson's, and dementia are chronic and advanced diseases that are associated with loss of neurons and other related pathologies. Furthermore, these disorders involve structural and functional defections of the blood-brain barrier (BBB). Consequently, advances in medicines and therapeutics have led to a better appreciation of various pathways associated with the development of neurodegenerative disorders, thus focusing on drug discovery and research for targeted drug therapy to the central nervous system (CNS). Although the BBB functions as a shield to prevent toxins in the blood from reaching the brain, drug delivery to the CNS is hindered by its presence. Owing to this, various formulation approaches, including the use of lipid-based nanocarriers, have been proposed to address shortcomings related to BBB permeation in CNS-targeted therapy, thus showing the potential of these carriers for translation into clinical use. Nevertheless, to date, none of these nanocarriers has been granted market authorization following the successful completion of all stages of clinical trials. While the aforementioned benefits of using lipid-based carriers underscores the need to fast-track their translational development into clinical practice, technological advances need to be initiated to achieve appropriate capacity for scale-up and the production of affordable dosage forms.

Using nanotechnology to deliver biomolecules from nose to brain - peptides, proteins, monoclonal antibodies and RNA

There is a growing number of biomolecules, including peptides, proteins, monoclonal antibodies and RNA, that could be potentially used for the treatment of central nervous system (CNS) diseases. However, the realization of their potential is being hampered by the extraordinary difficulties these complex biomolecules have to reach the brain in therapeutically meaningful amounts. Nose-to-brain (N-to-B) delivery is now being investigated as a potential option for the direct transport of biomolecules from the nasal cavity to different brain areas. Here, we discuss how different technological approaches enhance this N-to-B transport, with emphasis on those that have shown a potential for clinical translation. We also analyse how the physicochemical properties of nanocarriers and their modification with cell-penetrating peptides (CPPs) and targeting ligands affect their efficacy as N-to-B carriers for biomolecules.

Synthesis and Characterization of Fatty Acid Grafted Chitosan Polymeric Micelles for Improved Gene Delivery of VGF to the Brain through Intranasal Route

Multifunctional fatty acid grafted polymeric micelles are an effective and promising approach for drug and gene delivery to the brain. An alternative approach to bypass the blood-brain barrier is administration through intranasal route. Multifunctional fatty acid grafted polymeric micelles were prepared and characterized for pVGF delivery to the brain. In vitro pVGF expression was analyzed in bEnd.3 cells, primary astrocytes, and neurons. Comparative in-vivo pVGF expression was analyzed to evaluate the effective route of administration between intranasal and intravenous. Biocompatible, multifunctional polymeric micelles were prepared, having an average size of 200 nm, and cationic zeta potential. Modified polymers were found to be hemo- and cyto-compatible. When transfected with the different modified chitosan formulations, significantly (p < 0.05) higher VGF expression was observed in primary astrocytes and neurons using the mannose, Tat peptide, and oleic acid grafted chitosan polymer. Compared to intravenous administration, intranasal administration of pVGF in polyplex formulation led to significantly (p < 0.05) higher pVGF expression. Developed multifunctional polymeric micelles were an effective pVGF delivery platform to the brain. Mannose and Tat ligand tagging improved the pVGF delivery to the brain.

Nose-to-brain delivery: exploring newer domains for glioblastoma multiforme management

Glioblastoma multiforme (GBM) is the most common and aggressive form of the primary brain tumors in humans. The intricate pathophysiology, the development of resistance by tumor cells, and the inability of the drugs to effectively cross the blood-brain and blood-tumor barriers result in poor prognosis for GBM patients, with a median survival time of only 1 to 2 years. Nose-to-brain delivery offers an attractive, noninvasive strategy to enhance drug penetration or transport novel drug/gene carriers into the brain. Although the exact mechanism of intranasal delivery remains elusive, the olfactory and trigeminal nerve pathways have been found to play a vital role in circumventing the traditional barriers of brain targeting. This review discusses the intranasal pathway as a novel domain for delivering drugs and nanocarriers encapsulating drugs/genes, as well as stem cell carriers specifically to the glioma cells. Considering the fact that most of these studies are still in preclinical stage, translating such intranasal delivery strategies from bench to bedside would be a critical step for better management and prognosis of GBM. Graphical abstract.

Prior nasal delivery of antagomiR-122 prevents radiation-induced brain injury

Radiation-induced brain injury is a major adverse event in head and neck tumor treatment, influencing the quality of life for the more than 50% of patients who undergo radiation therapy and experience long-term survival. However, no effective treatments are available for these patients, and preventative drugs and effective drug-delivery methods must be developed. Based on our results, miR-122-5p was upregulated in the mouse radiation-induced brain injury (RBI) model and patients with nasopharyngeal carcinoma (NPC) who received radiation therapy. Intranasal administration of a single antagomiR-122-5p dose before irradiation effectively alleviated radiation-induced cognitive impairment, neuronal injury, and neuroinflammation in the mouse RBI model. Results further indicated that miR-122-5p inhibition in microglia reduced the levels of proinflammatory cytokines and enhanced the phagocytic function to protect against radiation-induced neuronal injury in cell models. Further, we profiled transcriptome data and verified that Tensin 1 (TNS1) may be the target of miR-122-5p in RBI. In summary, our results reveal a distinct role for miR-122-5p in regulating neuroinflammation in RBI, indicating that a non-invasive strategy for intranasal miR-122-5p administration may be an attractive therapeutic target in RBI, providing new insights for clinical trials. Further systematic safety assessment, optimization of drug administration, and clarity of mechanism will accelerate the process into clinical practice.

Convection enhanced delivery of light responsive antigen capturing oxygen generators for chemo-phototherapy triggered adaptive immunity

In recent years, combination therapy has emerged as the cornerstone of clinical practice in treating glioblastoma multiforme. However, their ability to trigger and leverage the body's adaptive immunity has rarely been studied. Tumour heterogeneity, the presence of the blood-brain barrier, and an immunosuppressive tumor microenvironment play a crucial role in the 90% local tumor recurrence post-treatment. Herein, we report an improved combination therapy approach capable of stimulating an immune response that utilizes Light responsive antigen-capturing oxygen generators (LAGs). The engineered LAGs loaded with a non-genotoxic molecule, Nutlin-3a, and a photosensitizer, Protoporphyrin IX, can release the payload on-demand when exposed to light of a specific wavelength. The in-situ oxygen generation capability of LAGs enables tumor oxygenation enhancement, thereby alleviating the tumor hypoxia and enhancing the efficacy of chemo-photodynamic therapy. Furthermore, by modulating the surface properties of LAGs, we demonstrated that the tumor-derived protein antigens released can be captured and retained in-situ, which improves antigen uptake and presentation by the antigen-presenting cells. Dual drug-loaded LAGs (DD-LAGs) upregulated the expression of cell surface CD83 maturation and CD86 costimulatory markers on monocyte-derived-dendritic cells, suggesting intrinsic immune adjuvancy. In the presence of 3D printed hypoxic U87 spheroids (h-U87), DD-LAGs induced cancer cell death, upregulated IL-1β, and downregulated IL-10 resulting in CD3⁺, helper CD4⁺, and cytotoxic CD8⁺ proliferation. Finally, we have investigated convection-enhanced delivery as a potential route of administration for DD-LAGs. Our work presents a novel strategy to induce tumor cell death both during and post-treatment, thereby reducing the possibility of recurrence.

Intranasal artesunate-loaded nanostructured lipid carriers: A convenient alternative to parenteral formulations for the treatment of severe and cerebral malaria

Early treatment with parenteral antimalarials is key in preventing deaths and complications associated with severe and cerebral malaria. This can be challenging in 'hard-to-reach' areas in Africa where transit time to hospitals with facilities to administer drugs parenterally can be more than 6 h. Consequently, the World Health Organization has recommended the use of artesunate (ATS) suppositories for emergency treatment of patients, however, this treatment is only for children under 6 years. The intranasal route (INR) can provide a safe and effective alternative to parenteral and rectal routes for patients of all ages; thus, reducing delays to the initiation of treatment. Hence, we designed ATS-loaded nanostructured lipid carriers (NLCs) for intranasal administration. ATS-NLCs were formulated using varying concentrations of lipid matrices made up of solidified reverse micellar solutions (SRMS) comprising a 1:2 ratio of Phospholipon ® 90H and lipids (Softisan ® 154 or Compritol ®). ATS-NLCs were spherical, and the small sizes of ATS-NLCs obtained for some formulations (76.56 ± 1.04 nm) is an indication that ATS-NLCs can pass through the nasal mucosa and reach the brain or systemic circulation. Encapsulation efficiency of ATS in NLCs was ≥70% for all formulations. ATS-NLCs achieved up to 40% in vitro drug release in 1 h, while ex vivo permeation studies revealed that formulating ATS as NLCs enhanced permeation through pig nasal mucosa better than drug solution. Most importantly, the activity and reduction in parasitaemia [in mice infected with Plasmodium berghei ANKA in a murine cerebral malaria model] by ATS-NLCs administered through the INR (54.70%, 33.28%) was comparable to intramuscular administration (58.80%, 42.18%), respectively. Therefore, intranasal administration of NLCs of ATS has great potentials to serve as a satisfactory alternative to parenteral administration for the treatment of severe and cerebral malaria in both adults and children in remote areas of sub-Saharan Africa.

Frontiers in the treatment of glioblastoma: Past, present and emerging

Glioblastoma (GBM) is one of the most aggressive cancers of the brain. Despite extensive research over the last several decades, the survival rates for GBM have not improved and prognosis remains poor. To date, only a few therapies are approved for the treatment of GBM with the main reasons being: 1) significant tumour heterogeneity which promotes the selection of resistant subpopulations 2) GBM induced immunosuppression and 3) fortified location of the tumour in the brain which hinders the delivery of therapeutics. Existing therapies for GBM such as radiotherapy, surgery and chemotherapy have been unable to reach the clinical efficacy necessary to prolong patient survival more than a few months. This comprehensive review evaluates the current and emerging therapies including those in clinical trials that may potentially improve both targeted delivery of therapeutics directly to the tumour site and the development of agents that may specifically target GBM. Particular focus has also been given to emerging delivery technologies such as focused ultrasound, cellular delivery systems nanomedicines and immunotherapy. Finally, we discuss the importance of developing novel materials for improved delivery efficacy of nanoparticles and therapeutics to reduce the suffering of GBM patients.

Intranasal drug delivery: opportunities and toxicologic challenges during drug development

Over the past 10 years, the interest in intranasal drug delivery in pharmaceutical R&D has increased. This review article summarises information on intranasal administration for local and systemic delivery, as well as for CNS indications. Nasal delivery offers many advantages over standard systemic delivery systems, such as its non-invasive character, a fast onset of action and in many cases reduced side effects due to a more targeted delivery. There are still formulation limitations and toxicological aspects to be optimised. Intranasal drug delivery in the field of drug development is an interesting delivery route for the treatment of neurological disorders. Systemic approaches often fail to efficiently supply the CNS with drugs. This review paper describes the anatomical, histological and physiological basis and summarises currently approved drugs for administration via intranasal delivery. Further, the review focuses on toxicological considerations of intranasally applied compounds and discusses formulation aspects that need to be considered for drug development.

Nose-to-brain delivery of disulfiram nanoemulsion in situ gel formulation for glioblastoma targeting therapy

Glioblastoma (GBM) is a difficult-to-treat cancer, likely attributed to the blood brain barrier and drug resistance. Nose-to-brain drug delivery is a direct and non-invasive pathway for brain targeting with low systemic toxicity. Disulfiram (DSF) has shown its effectiveness against GBM, especially with copper ion (Cu). In this work, we designed a DSF loaded ion-sensitive nanoemulsion in situ gel (DSF-INEG) that was delivered intranasally along with Cu to the rat brains for the GBM treatment. The developed DSF-INEG nanomedicine showed a suitable particle size of 63.4 ± 1.1 nm and zeta potential of -23.5 ± 0.2 mV with a favorable gelling ability and prolonged DSF release. The results in vitro indicate DSF-INEG/Cu effectively inhibited the proliferation of both C6 and U87 cells. Besides, the excellent brain-targeting efficacy via nose-to-brain delivery was proved by the highest fluorescence signal of Cy5.5-INEG in the rat brains. Moreover, GFP imaging showed enhanced tumor growth inhibition of the rats by the DSF-INEG/Cu treatment, and their median survival time was 1.6 and 1.2 folds than those of the rats in the control and DSF/Cu treated groups, respectively, with no obvious histopathological damage to normal tissues. Overall, DSF-INEG/Cu could be a promising intranasal nanomedicine for effective GBM treatment.

CCRD based development of bromocriptine and glutathione nanoemulsion tailored ultrasonically for the combined anti-parkinson effect

Bromocriptine Mesylate (BRM) acts as a dopamine receptor agonist along with antioxidant effect and is utilized in the treatment of Parkinson's disease (PD). Glutathione (GSH) is a thiol- reducing agent having antioxidant properties in the brain. Replenishment of GSH inside the brain can play a major role in the management of PD. Both BRM and GSH suffer from low oral bioavailability and poor absorption. The objective of the present study was to develop BRM and GSH loaded nanoemulsion for the combined and synergistic effect delivered through the intranasal route for the better and effective management of PD. After extensive screening experiments, Capmul PG-8 NF was selected as oil, polyethylene glycol (PEG) 400 as a surfactant and propylene glycol as co-surfactant. Ultrasonication technique was employed for the fabrication of nanoemulsion. Central composite rotatable design (CCRD) was used to obtain the best formulation by optimization. Oil (%), S_mix (%), and sonication time (second) were chosen as independent variables for the optimization. Particle size, PDI, zeta potential, % transmittance, pH, refractive index, viscosity and conductivity of the optimized nanoemulsion were found to be 80.71 ± 2.75 nm, 0.217 ± 0.009, -12.60 ± 0.10 mV, 96.00 ± 3.05 %, 6.48 ± 0.28, 1.36 ± 0.03, 30.12 ± 0.10 mPas and 214.28 ± 2.79 μS/cm respectively. Surface morphology demonstrated that nanoemulsion possessed spherical and globular nature of the particle which showed 3.4 times and 1.5 times enhancement in drug permeation in the case of BRM and GSH respectively as compared to suspension. MTT assay done on neuro-2a cell lines revealed that nanoemulsion was safe for intranasal delivery. Behavioural studies were carried out to prove the efficacy of optimized nanoemulsion in PD using forced swimming test, locomotor activity test, catalepsy test, rota-rod test, and akinesia test in Wistar rats. The outcomes of the behavioural studies revealed that BRM and GSH loaded nanoemulsion treatment showed significant improvement in behavioural activities of PD (haloperidol-induced) rats after intranasal administration. This study concluded that BRM and GSH loaded nanoemulsion could be promising for the combined and synergistic anti-parkinson effect for the effective management of PD.

Intranasal administration of perillyl alcohol-loaded nanoemulsion and pharmacokinetic study of its metabolite perillic acid in plasma and brain of rats using ultra-performance liquid chromatography/tandem mass spectrometry

Perillyl alcohol (POH) is a monocyclic terpene that has strong antitumor activity. Brain tumors are particularly difficult to treat with therapeutic agents, and clinical trials have shown their low tolerance through oral administration. We proposed the entrapment of POH into an oil-in-water chitosan nanoemulsion aiming its intranasal administration for brain targeting. An ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantitation of total metabolite perillic acid (PA) in plasma and brain of rats. The rat samples containing the metabolite were treated by liquid-liquid extraction with acetonitrile. The mobile phase was 0.1% formic acid in water (solvent A) and 0.1% formic acid in methanol (solvent B), at a flow rate of 0.3 mL min^-1 in gradient elution. The chromatography was run for 10 min, and analytical curves were built in acetonitrile, plasma, and brain. The PA was detected in positive ion mode with multiple reaction monitoring. The method has shown high selectivity, sensitivity, and throughput. The low quantification limits of 162, 178, and 121 ng mL^-1 for acetonitrile, brain, and plasma, respectively, indicate a good detectability of the method. The repeatability and precision observed were within the limits recommended in the literature. The accuracy of the method was verified through high recovery rates (106-118%). The validated method was successfully applied to the pharmacokinetic study of the metabolite PA after the intranasal administration of free or POH-loaded nanoemulsion in rats. The results showed that chitosan nanoemulsion improved the plasma and brain bioavailability of POH, representing a promising alternative to free POH treatment.

Nose-to-brain Delivery of Natural Compounds for the Treatment of Central Nervous System Disorders

BACKGROUND

Several natural compounds have demonstrated potential for the treatment of central nervous system disorders such as ischemic cerebrovascular disease, glioblastoma, neuropathic pain, neurodegenerative diseases, multiple sclerosis and migraine. This is due to their well-known antioxidant, anti-inflammatory, neuroprotective, anti-tumor, anti-ischemic and analgesic properties. Nevertheless, many of these molecules have poor aqueous solubility, low bioavailability and extensive gastrointestinal and/or hepatic first-pass metabolism, leading to a quick elimination as well as low serum and tissue concentrations. Thus, the intranasal route emerged as a viable alternative to oral or parenteral administration, by enabling a direct transport into the brain through the olfactory and trigeminal nerves. With this approach, the blood-brain barrier is circumvented and peripheral exposure is reduced, thereby minimizing possible adverse effects.

OBJECTIVE

Herein, brain-targeting strategies for nose-to-brain delivery of natural compounds, including flavonoids, cannabinoids, essential oils and terpenes, will be reviewed and discussed. Brain and plasma pharmacokinetics of these molecules will be analyzed and related to their physicochemical characteristics and formulation properties.

CONCLUSION

Natural compounds constitute relevant alternatives for the treatment of brain diseases but often require loading into nanocarrier systems to reach the central nervous system in sufficient concentrations. Future challenges lie in a deeper characterization of their therapeutic mechanisms and in the development of effective, safe and brain-targeted delivery systems for their intranasal administration.

Management of epileptic disorders using nanotechnology-based strategies for nose-to-brain drug delivery

INTRODUCTION

Epilepsy, a major neurological disorder affects about 1% of the Indian population. The discovery of noninvasive strategies for epilepsy presents a challenge for the scientists. Different types of nose-to-brain dosage-forms have been studied for epilepsy management. It aims to give new perspectives for developing new and existing anti-epileptic drugs. Combining nanotechnology with nose-to-brain approach can help in promoting the treatment efficacy by site-specific delivery. Also, it will minimize the side-effects and patient noncompliance observed in conventional administration routes. Peptide delivery can be an interesting approach for the management of epilepsy. Drug-loaded intranasal nanoformulations exhibit diverse prospective potentials in the management of epilepsy. Considering that, nanotherapy using nose-to-brain delivery as a prospective technique for the efficient management of epilepsy is reviewed.

AREAS COVERED

The authors have compiled all recently available data pertaining to the nose-to-brain delivery of therapeutics using nanotechnological strategies. The fundamental mechanism of nose-to-brain delivery, claims for intranasal delivery and medical devices for epilepsy are discussed.

EXPERT OPINION

Drug-loaded intranasal nanoformulations exhibit different prospective potentials in the management of epilepsy. Considering the foregoing research done in the field of nanotechnology, globally, authors propose nose-to-brain delivery of nanoformulations as a potential technique for the efficient management of epilepsy.

Preparation and Evaluation of Mebendazole Microemulsion for Intranasal Delivery: an Alternative Approach for Glioblastoma Treatment

Although mebendazole (MBZ) has demonstrated antitumor activity in glioblastoma models, the drug has low aqueous solubility and therefore is poorly absorbed. Considering that other strategies are needed to improve its bioavailability, the current study was aimed to develop and evaluate novel microemulsions of MBZ (MBZ-NaH ME) for intranasal administration. MBZ raw materials were characterized by FTIR, DSC, and XDP. Subsequently, the raw material that contained mainly polymorph C was selected to prepare microemulsions. Two different oleic acid (OA) systems were selected. Formulation A was composed of OA and docosahexaenoic acid (3:1% w/w), while formulation B was composed of OA and Labrafil M2125 (1:1% w/w). Sodium hyaluronate (NaH) at 0.1% was selected as a mucoadhesive agent. MBZ MEs showed a particle size of 209 nm and 145 nm, respectively, and the pH was suitable for nasal formulations (4.5-6.5). Formulation B, which showed the best solubility and rheological behavior, was selected for intranasal evaluation. The nasal toxicity study revealed no damage in the epithelium. Furthermore, formulation B improved significantly the median survival time in the orthotopic C6 rat model compared to the control group. Moreover, NIRF signal intensity revealed a decrease in tumor growth in the treated group with MBZ-MaH ME, which was confirmed by histologic examinations. Results suggest that the intranasal administration of mebendazole-loaded microemulsion might be appropriated for glioblastoma treatment. Graphical abstract.

Stimuli-responsive In situ gelling system for nose-to-brain drug delivery

The diagnosis and treatment of neurological ailments always remain an utmost challenge for research fraternity due to the presence of BBB. The intranasal route appeared as an attractive and alternative route for brain targeting of therapeutics without the intrusion of BBB and GI exposure. This route directly and effectively delivers the therapeutics to different regions of the brain via olfactory and trigeminal nerve pathways. However, shorter drug retention time and mucociliary clearance curtail the efficiency of the intranasal route. The in situ mucoadhesive gel overthrow the limitations of direct nose-to-brain delivery by not only enhancing nasal residence time but also minimizing the mucociliary clearance and enzymatic degradation. This delivery system further improves the nasal absorption as well as bioavailability of drugs in the brain. The in situ mucoadhesive gel is a controlled and sustained release system that facilitates the absorption of various proteins, peptides and other larger lipophilic and hydrophilic moieties. Owing to multiple benefits, in situ gelling system has been widely explored to target the brain via nasal route. However, very few review works are reported which explains the application of in situ nasal gel for brain delivery of CNS acting moieties. Hence, in this piece of work, we have initially discussed the global statistics of neurological disorders reported by WHO and other reputed organizations, nasal anatomy, mechanism and challenges of nose-to-brain drug delivery. The work mainly focused on the use of different stimuli-responsive polymers, specifically thermoresponsive, pH-responsive, and ion triggered systems for the development of an effective and controlled dosage form, i.e., in situ nasal gel for brain targeting of bioactives. We have also highlighted the origin, structure, nature and phase transition behavior of the smart polymers found suitable for nasal administration, including poloxamer, chitosan, EHEC, xyloglucan, Carbopol, gellan gum and DGG along with their application in the treatment of neurological disorders. The article is aimed to gather all the information of the past 10 years related to the development and application of stimuli-responsive in situ nasal gel for brain drug delivery.

QbD-driven development of intranasal lipid nanoparticles for depression treatment

Depression is a life-threatening psychiatric disorder and a multifactorial global public health concern. Current pharmacological treatments present limited efficacy, and are associated with several harmful side effects and development of pharmacoresistance mechanisms. Developing more effective therapeutic options is therefore a priority. This work aims at efficiently designing an antidepressant therapeutic surrogate relying on a dual strategy supported on lipid nanoparticles and intranasal delivery. For that purpose, the formulation was comprehensively optimized following a quality by design perspective. Critical quality attributes (CQAs) ranged from physicochemical to intranasal performance features. The optimized formulation was administered to mice in order to assess the antidepressive and anxiolytic effects by applying the forced swimming and marble-burying tests, respectively. A cross-analysis of the predictive models established for the set of 12 CQAs elicited the formulation containing similar proportion of solid and liquid lipids and lower surfactant concentration as the optimal one. Despite increasing the liquid lipid amount yielded smaller and more homogeneous particle size, and higher release rate, nanostructured lipid carriers (NLCs) provided an earlier and superior pig nasal mucosa permeability than nanoemulsions, along with better stability and cytotoxic profiles. Importantly, the intranasal delivery of the optimal lipid nanoparticle formulation reduced both depressive and anxiety-like behaviors, which positions these intranasal nanosystems in line with the hypothesis of provisioning timely and better acting antidepressant therapies.

Drug Delivery and Targeting to the Brain Through Nasal Route: Mechanisms, Applications and Challenges

Blood-brain barrier (BBB) provides restrictions for the transportation of various therapeutic agents to the brain. Efforts to directly target the brain by olfactory as well as trigeminal nerve pathway, bypassing BBB, have grown significantly in recent times. The intranasal route of transportation of the drug encompasses ability for the delivery of drug directly to the brain, improves site-specificity in the brain and avoids systemic side effects. In the current era, novel drug delivery systems are useful tools for targeting the brain without providing any harmful effects in nasal mucosa as well as the central nervous system. The complex structure of nasal cavity, mucociliary clearance, degradation by the enzymes present in nasal cavity and pathological conditions like rhinitis, common cold, etc. are the major disputes for nasal drug delivery. The use of nanotechnological approaches like solid lipid nanoparticles, polymeric nanoparticles, nanoemulsions, liposomes and polymeric micelles provides the ability to overcome these barriers. There are several emerging nasal drug delivery technologies produced by various pharmaceutical companies to conquer these hurdles. This review tries to address the recent developments in the area of direct drug delivery to the brain through the nasal route.

PEGylation and folate conjugation effects on the stability of chitosan-tripolyphosphate nanoparticles

Chitosan-based nanoparticles (Ch-NPs) prepared via ionotropic gelation of Ch with sodium tripolyphosphate (TPP) have been widely examined as potential drug carriers. Yet, recent studies have shown these particles to be unstable in model (pH 7.2-7.4) physiological media. To this end, here we explored the possibility of improving TPP-crosslinked Ch-NP stability through chemical Ch modification. Specifically, Ch samples with either 76% or 92% degrees of deacetylation (DD) were grafted with either polyethylene glycol (PEG), a hydrophilic molecule, or folic acid (F), a hydrophobic molecule. Limited variation in dispersion light scattering intensity, particle size and apparent ζ-potential, and lack of macroscopic precipitation were chosen as analytical evidence of dispersion stability. TPP titrations were performed to determine the optimal TPP:glucosamine molar ratio for preparing particles with near 200-nm diameters, which are desirable for systemic administration of drugs, cellular uptake, and enhancing NP blood circulation. Both DD and Ch modification influenced the particle formation process and the evolution in NP size and ζ-potential upon 30-day storage in virtually salt-free water at 25 °C and 37 °C, where the NPs underwent partial aggregation (along with possible dissolution and swelling) but remained colloidally dispersed. Under model physiological (pH 7.2; 163 mM ionic strength) conditions, however (where the chitosan amine groups were largely deprotonated), the particles quickly became destabilized, evidently due to particle dissolution followed by Ch precipitation. Overall, within the degrees of substitution used for this work (~1% for PEG, and 3 and 6% for F), neither PEG nor F qualitatively improved Ch-NP stability at physiological pH 7.2 conditions. Thus, application of TPP-crosslinked Ch-NPs in drug delivery (even when Ch is derivatized with PEG or F) should likely be limited to administration routes with acidic pH (at which these NPs remain stable).

Nose-to-Brain Delivery of Cancer-Targeting Paclitaxel-Loaded Nanoparticles Potentiates Antitumor Effects in Malignant Glioblastoma

Glioblastoma multiforme (GBM) is an aggressive tumor with no curative treatment. The tumor recurrence after resection often requires chemotherapy or radiation to delay the infiltration of tumor remnants. Intracerebral chemotherapies are preferentially being used to prevent tumor regrowth, but treatments remain unsuccessful because of the poor drug distribution in the brain. In this study, we investigated the therapeutic efficacy of cancer-targeting arginyl-glycyl-aspartic tripeptide (RGD) conjugated paclitaxel (PTX)-loaded nanoparticles (NPs) against GBM by nose-to-brain delivery. Our results demonstrated that RGD-modified PTX-loaded NPs showed cancer-specific delivery and enhanced anticancer effects in vivo. The intranasal (IN) inoculation of RGD-PTX-loaded NPs effectively controls the tumor burden (75 ± 12% reduction) by inducing apoptosis and/or inhibiting cancer cell proliferation without affecting the G₀ stage of normal brain cells. Our data provide therapeutic evidence supporting the use of intranasally delivered cancer-targeted PTX-loaded NPs for GBM therapy.

Approaches for CNS delivery of drugs - nose to brain targeting of antiretroviral agents as a potential attempt for complete elimination of major reservoir site of HIV to aid AIDS treatment

INTRODUCTION

Human immune-deficiency virus (HIV) infection causing acquired immune-deficiency syndrome (AIDS) is one of the most life-threatening infections. The central nervous system (CNS) is reported to be the most important HIV reservoir site where the antiretroviral drugs are unable to reach.

AREAS COVERED

This article includes the review about HIV infections, its pathogenesis, HIV infections in CNS, its consequences, current therapies, challenges associated with the existing therapies, approaches to overcome them, CNS delivery of drugs - barriers, transport routes, approaches for transporting drugs across the blood-brain barrier, nasal route of drug delivery, and nose to brain targeting of antiretroviral agents as a potential approach for complete cure of AIDS.

EXPERT OPINION

Various approaches are exploited to enhance the drug delivery to the brain for various categories of drugs. However, very few have investigated on the delivery of antiretrovirals to the brain. Targeting antiretrovirals to CNS through oral/nasal routes along with oral/parenteral delivery of drug to the plasma can be a promising approach for an attempt to completely eradicate HIV reservoir and cure AIDS, after clinical trials. Further research is required to identify the exact location of the HIV reservoir in CNS and developing good animal models for evaluation of different newly developed formulations.

Intranasal delivery of cancer-targeting doxorubicin-loaded PLGA nanoparticles arrests glioblastoma growth

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumour and treatment is very challenging. Despite the recent advances in drug delivery systems, various approaches that allow sufficient deposition of anti-cancer drugs within the brain remain unsuccessful due to limited drug delivery throughout the brain. In this study, we utilised an intranasal (IN) approach to allow delivery of anti-cancer drug, encapsulated in PLGA nanoparticles (NPs). PLGA NPs were modified with the RGD ligand to enable A_vβ₃ expressing tumour-specific delivery. IN delivery of RGD-conjugated-doxorubicin (DOX)-loaded-PLGA-nanoparticles (RGD-DOX-NP) showed cancer-specific delivery of NP and inhibition of brain tumour growth compared to the free-DOX or non-modified DOX-NP in the C6-implanted GBM model. Further, IN treatment with RGD-DOX-NP induces apoptosis in the tumour region without affecting normal brain cells. Our study provides therapeutic evidence to treat GBM using a non-invasive IN approach, which may further be translated to other brain-associated diseases.

Ligand Conjugated Targeted Nanotherapeutics for Treatment of Neurological Disorders

BACKGROUND

Human brain is amongst the most complex organs in human body, and delivery of therapeutic agents across the brain is a tedious task. Existence of blood brain barrier (BBB) protects the brain from invasion of undesirable substances; therefore it hinders the transport of various drugs used for the treatment of different neurological diseases including glioma, Parkinson's disease, Alzheimer's disease, etc. To surmount this barrier, various approaches have been used such as the use of carrier mediated drug delivery; use of intranasal route, to avoid first pass metabolism; and use of ligands (lactoferrin, apolipoprotein) to transport the drug across the BBB. Ligands bind with proteins present on the cell and facilitate the transport of drug across the cell membrane via. receptor mediated, transporter mediated or adsorptive mediated transcytosis.

OBJECTIVE

The main focus of this review article is to illustrate various studies performed using ligands for delivering drug across BBB; it also describes the procedure used by various researchers for conjugating the ligands to the formulation to achieve targeted action.

METHODS

Research articles that focused on the used of ligand conjugation for brain delivery and compared the outcome with unconjugated formulation were collected from various search engines like PubMed, Science Direct and Google Scholar, using keywords like ligands, neurological disorders, conjugation, etc. Results and Conclusion: Ligands have shown great potential in delivering drug across BBB for treatment of various diseases, yet extensive research is required so that the ligands can be used clinically for treating neurological diseases.

Overview of Current Drug Delivery Methods Across the Blood-Brain Barrier for the Treatment of Primary Brain Tumors

Existing drug delivery methods have not led to a significant increase in survival for patients with malignant primary brain tumors. While the combination of conventional therapies consisting of surgery, radiotherapy, and chemotherapy has improved survival for some types of brain tumors (e.g., WNT medulloblastoma), other types of brain tumors (e.g., glioblastoma and diffuse midline glioma) still have a poor prognosis. The reason for the differences in response can be largely attributed to the blood-brain barrier (BBB), a specialized structure at the microvasculature level that regulates the transport of molecules across the blood vessels into the brain parenchyma. This structure hampers the delivery of most chemotherapeutic agents for the treatment of primary brain tumors. Several drug delivery methods such as nanoparticles, convection enhanced delivery, focused ultrasound, intranasal delivery, and intra-arterial delivery have been developed to overcome the BBB in primary brain tumors. However, prognosis of most primary brain tumors still remains poor. The heterogeneity of the BBB in primary brain tumors and the distinct vasculature of tumors make it difficult to design a drug delivery method that targets the entire tumor. Drug delivery methods that combine strategies such as focused ultrasound and nanoparticles might be a more successful approach. However, more research is needed to optimize and develop new drug delivery techniques to improve survival of patients with primary brain tumors.

The Nose-To-Brain Transport of Polymeric Nanoparticles Is Mediated by Immune Sentinels and Not by Olfactory Sensory Neurons

The nose-to-brain (N-to-B) transport mechanism of nanoparticles through the olfactory epithelium (OE) is not fully understood. Most research utilized nasal epithelial cell models completely deprived of olfactory cells. Aiming to shed light into key cellular pathways, in this work, for the first time, the interaction of polymeric nanoparticles in a 17-483 nm size range and with neutral and negatively and positively charged surfaces with primary olfactory sensory neurons, cortical neurons, and microglia isolated from olfactory bulb (OB), OE, and cortex of newborn rats is investigated. After demonstrating the good cell compatibility of the different nanoparticles, the nanoparticle uptake by confocal laser scanning fluorescence microscopy is monitored. Our findings reveal that neither olfactory nor forebrain neurons internalize nanoparticles. Conversely, it is demonstrated that olfactory and cortical microglia phagocytose the nanoparticles independently of their features. Overall, our findings represent the first unambiguous evidence of the possible involvement of microglia in N-to-B nanoparticle transport and the unlikely involvement of neurons. Furthermore, this approach emerges as a completely new experimental tool to screen the biocompatibility, uptake, and transport of nanomaterials by key cellular players of the N-to-B pathway in nanosafety and nanotoxicology and nanomedicine.

Brain Targeting of Acyl-CoA:Cholesterol O-Acyltransferase-1 Inhibitor K-604 via the Intranasal Route Using a Hydroxycarboxylic Acid Solution

An acyl-CoA:cholesterol O-acyltransferase-1 (ACAT-1/SOAT-1) inhibitor, K-604 is a promising drug candidate for the treatment of Alzheimer's disease and glioblastoma; however, it exhibits poor solubility in neutral water and low permeability across the blood-brain barrier. In this study, we report the successful delivery of K-604 to the brain via the intranasal route in mice using a hydroxycarboxylic acid solution. In cerebral tissue, the AUC of K-604 after intranasal administration (10 μL; 108 μg of K-604/mouse) was 772 ng·min/g, whereas that after oral administration (166 μg of K-604/mouse) was 8.9 ng·min/g. Thus, the index of brain-targeting efficiency was 133-fold based on the dose conversion. Even with intranasal administration of K-604 once per day for 7 days, the level of cholesteryl esters markedly decreased from 0.70 to 0.04 μmol/g in the mouse brain. Thus, this application will be a crucial therapeutic solution for ACAT-1 overexpressing diseases in the brain.

Intracellular cholesterol trafficking is dependent upon NPC2 interaction with lysobisphosphatidic acid

Unesterified cholesterol accumulation in the late endosomal/lysosomal (LE/LY) compartment is the cellular hallmark of Niemann-Pick C (NPC) disease, caused by defects in the genes encoding NPC1 or NPC2. We previously reported the dramatic stimulation of NPC2 cholesterol transport rates to and from model membranes by the LE/LY phospholipid lysobisphosphatidic acid (LBPA). It had been previously shown that enrichment of NPC1-deficient cells with LBPA results in cholesterol clearance. Here we demonstrate that LBPA enrichment in human NPC2-deficient cells, either directly or via its biosynthetic precursor phosphtidylglycerol (PG), is entirely ineffective, indicating an obligate functional interaction between NPC2 and LBPA in cholesterol trafficking. We further demonstrate that NPC2 interacts directly with LBPA and identify the NPC2 hydrophobic knob domain as the site of interaction. Together these studies reveal a heretofore unknown step of intracellular cholesterol trafficking which is critically dependent upon the interaction of LBPA with functional NPC2 protein.

Cholesterol is a type of fat that is essential for many processes in the body, such as repairing damaged cells and producing certain hormones. Normally, cholesterol enters cells from the bloodstream and is then moved to the parts of the cell that need it via a process known as ‘trafficking’.

When cholesterol trafficking goes wrong, abnormally large amounts of cholesterol and other fats accumulate within the cell. Over time, these fatty deposits become toxic to cells and eventually damage the affected tissues. Niemann-Pick type C disease (NPC) is a severe genetic disorder affecting cholesterol trafficking. It is characterized by cholesterol build-up in multiple tissues, including the brain, which ultimately causes degeneration and death of nerve cells.

Two proteins, NPC1 and NPC2, are involved in NPC disease. Both proteins normally help move cholesterol out of important trafficking compartments (known as the endosomal and lysosomal compartments) to other areas of the cell where it is needed. Patients with the disease can have mutations in either the gene for NPC1 or the gene for NPC2. This means that cells from NPC1 patients do not make enough functional NPC1 protein (but contain working NPC2), and vice versa.

Previous studies had shown that giving cells with NPC1 mutations large amounts of the small molecule lysobisphosphatidic acid (LBPA for short) could compensate for the loss of NPC1, and stop the toxic build-up of cholesterol. McCauliff, Langan, Li et al. therefore wanted to explore exactly how LBPA was doing this. They had shown that LBPA dramatically increased the ability of purified NPC2 protein to transport cholesterol, and wondered if the effect of LBPA in the cells without NPC1 depended on NPC2. They predicted that boosting LBPA levels would not work in cells lacking NPC2.

Biochemical experiments using purified protein showed that LBPA and NPC2 did indeed interact directly with each other. Systematically changing different building blocks of NPC2 revealed that a single region of the protein is sensitive to LBPA, and when this region was altered, LBPA could no longer interact with NPC2. Since LBPA is naturally produced by cells, they then stimulated cells grown in the laboratory to generate more LBPA using its precursor phosphatidylglycerol. They used cells from patients with mutations in either NPC1 or NPC2 and demonstrated that LBPA’s ability to reverse the accumulation of cholesterol was dependent on its interaction with NPC2. Thus, increasing LBPA levels in cells from patients with NPC1 mutations was beneficial, but had no effect on cells from patients with NPC2 mutations.

These results shed new light not only on how cells transport cholesterol, but also on potential methods to combat disorders of cellular cholesterol trafficking. In the future, LBPA could be developed as a genetically tailored, patient-specific therapy for diseases like NPC.

Chitosan-hyaluronan: promotion of mucociliary differentiation of respiratory epithelial cells and development of olfactory receptor neurons

Developing a biomaterial that promotes regeneration of both respiratory epithelium (RE) and olfactory neuroepithelium (ON) improves the surgical outcome of endoscopic sinus surgery. Although chitosan (CS) inhibits mucociliary differentiation of RE, it has been reported to regenerate ON. In addition, hyaluronic acid (HA) has been demonstrated to promote regeneration of RE. Whether the composite CS + HA would simultaneously benefit RE and ON remains unexplored. Human nasal respiratory epithelial cells (RECs) and olfactory neuroepithelial cells (ONCs) are respectively obtained from the RE and the ON. They are cultured in vitro and divided into groups undergoing four treatments, control, CS, HA, and CS + HA and assessed by scanning electron microscope, immunocytochemistry, and Western blots following indicated growth conditions. RECs keep polygonal morphology with mucociliary differentiation in the CS + HA group. The levels of E-cadherin, zonula occludens-1, mucin 5AC, and forkhead box protein J1 are significantly higher in the CS + HA group than in the CS alone group. In addition, ONCs express lower cytokeratin 18 (CK18) and higher olfactory marker protein (OMP) in the CS + HA group than in HA alone group. ONCs express more signal transduction apparatuses, adenylate cyclase 3, in CS and CS + HA groups than in HA and controls. Chitosan-hyaluronan plays a part in promoting differentiation of ORNs and facilitating mucociliary differentiation of RECs. This composite is a promising biomaterial for the sinonasal application.

Antidepressants and nose-to-brain delivery: drivers, restraints, opportunities and challenges

Why is nose-to-brain delivery considered to be a strategy that directly allows the access of antidepressants to the brain? In which circumstances can the intranasal pathway be applicable? Are there any requirements to follow? What triggers the antidepressant market? Which constraints are imposed during discovery programs? What opportunities can arise and what is their current status of development? Are they already translated into clinical practice? Which challenges are expected from recent development strategies? This review aims at providing a critical appraisal of nose-to-brain delivery of antidepressants, framed within a comprehensive analysis of drivers, restraints, opportunities and challenges.