Nose-to-Brain Delivery

Design and development of a chitosan-based nasal powder of dimethyl fumarate-cyclodextrin binary systems aimed at nose-to-brain administration. A stability study

The nasal administration route has been studied for the delivery of active molecules directed to the Central Nervous System, thanks to the anatomical connection between the nasal cavity and the brain. Dimethyl fumarate is used to treat relapsing-remitting multiple sclerosis, with a role as an immunomodulator towards T- T-cells and a cytoprotector towards neurons and glial cells. Its use in therapy is hindered by its low aqueous solubility, and low stability, due to hydrolysis and sublimation at room temperature. To overcome this limitation, in this study we evaluated the feasibility of using two amorphous β-cyclodextrin derivatives, namely hydroxypropyl β-cyclodextrin and methyl β-cyclodextrin, to obtain a nasally administrable powder with a view to nose-to-brain administration. Initially, the interaction product was studied using different analytical methods (differential scanning calorimetry, Fourier transform infrared spectroscopy and powder X-ray diffraction) to detect the occurrence of binary product formation, while phase solubility analysis was used to probe the complexation in solution. The dimethyl fumarate-cyclodextrin binary product showing best solubility and stability properties was subsequently used in the development of a chitosan-based mucoadhesive nasally administrable powder comparing different preparative methods. The best performance in terms of both hydrolytic stability and DMF recovery was achieved by the powder obtained via freeze-drying.

A neoteric annotation on the advances in combination therapy for Parkinson's disease: nanocarrier-based combination approach and future anticipation. Part II: nanocarrier design and development in focus

INTRODUCTION

The current treatment modalities available for Parkinson's disease (PD) prove inadequate due to the inherent constraints in effectively transporting bioactive compounds across the blood-brain barrier. The utilization of synergistic combinations of multiple drugs in conjunction with advanced nanotechnology, emerges as a promising avenue for the treatment of PD, offering potential breakthroughs in treatment efficacy, targeted therapy, and personalized medicine.

AREAS COVERED

This review provides a comprehensive analysis of the efficacy of multifactorial interventions for PD, simultaneously addressing the primary challenges of conventional therapies and highlighting how advanced technologies can help overcome these limitations. Part II focuses on the effectiveness of nanotechnology for improving pharmacokinetics of conventional therapies, through the synergistic use of dual or multiple therapeutic agents into a single nanoformulation. Significant emphasis is laid on the advancements toward innovative integrations, such as CRISPR/Cas9 with neuroprotective agents and stem cells, all effectively synergized with nanocarriers.

EXPERT OPINION

By using drug combinations, we can leverage their combined effects to enhance treatment efficacy and mitigate side effects through lower dosages. This article is meant to give nanocarrier-mediated co-delivery of drugs and the strategic incorporation of CRISPR/Cas9, either as an independent intervention or synergized with a neuroprotective agent.

How to use an in vitro approach to characterize the toxicity of airborne compounds

As part of the development of new approach methodologies (NAMs), numerous in vitro methods are being developed to characterize the potential toxicity of inhalable xenobiotics (gases, volatile organic compounds, polycyclic aromatic hydrocarbons, particulate matter, nanoparticles). However, the materials and methods employed are extremely diverse, and no single method is currently in use. Method standardization and validation would raise trust in the results and enable them to be compared. This four-part review lists and compares biological models and exposure methodologies before describing measurable biomarkers of exposure or effect. The first section emphasizes the importance of developing alternative methods to reduce, if not replace, animal testing (3R principle). The biological models presented are mostly to cultures of epithelial cells from the respiratory system, as the lungs are the first organ to come into contact with air pollutants. Monocultures or cocultures of primary cells or cell lines, as well as 3D organotypic cultures such as organoids, spheroids and reconstituted tissues, but also the organ(s) model on a chip are examples. The exposure methods for these biological models applicable to airborne compounds are submerged, intermittent, continuous either static or dynamic. Finally, within the restrictions of these models (i.e. relative tiny quantities, adhering cells), the mechanisms of toxicity and the phenotypic markers most commonly examined in models exposed at the air-liquid interface (ALI) are outlined.

Feasibility Study of Developing a Saline-Based Antiviral Nanoformulation Containing Lipid-Soluble EGCG: A Potential Nasal Drug to Treat Long COVID

A recent estimate indicates that up to 23.7 million Americans suffer from long COVID, and approximately one million workers may be out of the workforce each day due to associated symptoms, leading to a USD 50 billion annual loss of salary. Post-COVID (Long COVID) neurologic symptoms are due to the initial robust replication of SARS-CoV-2 in the nasal neuroepithelial cells, leading to inflammation of the olfactory epithelium (OE) and the central nervous system (CNS), and the OE becoming a persistent infection site. Previously, our group showed that Epigallocatechin-3-gallate-palmitate (EC16) nanoformulations possess strong antiviral activity against human coronavirus, suggesting this green tea-derived compound in nanoparticle formulations could be developed as an intranasally delivered new drug to eliminate the persistent SARS-CoV-2 infection, leading to restored olfactory function and reduced inflammation in the CNS. The objective of the current study was to determine the compatibility of the nanoformulations with human nasal primary epithelial cells (HNpECs).

METHODS

Nanoparticle size was measured using the ZetaView Nanoparticle Tracking Analysis (NTA) system; contact antiviral activity was determined by TCID50 assay for cytopathic effect on MRC-5 cells; post-infection inhibition activity was determined in HNpECs; and cytotoxicity for these cells was determined using an MTT assay. The rapid inactivation of OC43 (a β-coronavirus) and 229E (α-coronavirus) viruses was further characterized by transmission electron microscopy.

RESULTS

A saline-based nanoformulation containing 0.1% w/v EC16 was able to inactivate 99.9999% β-coronavirus OC43 on direct contact within 1 min. After a 10-min incubation of infected HNpECs with a formulation containing drug-grade EC16 (EGCG-4' mono-palmitate or EC16m), OC43 viral replication was inhibited by 99%. In addition, all nanoformulations tested for their effect on cell viability were comparable to normal saline, a regularly used nasal irrigation solution. A 1-min incubation of an EC16 nanoformulation with either OC43 or 229E showed an altered viral structure.

CONCLUSION

Nanoformulations containing EC16 showed properties compatible with nasal application to rapidly inactivate SARS-CoV-2 residing in the olfactory mucosa and to reduce inflammation in the CNS, pending additional formulation and safety studies.

Nanocarrier Mediated Intranasal Drug Delivery Systems for the Management of Parkinsonism: A Review

The transport of drugs to the brain becomes a key concern when treating disorders of the central nervous system. Parkinsonism is one of the major concerns across the world populations, which causes difficulty in coordination and balance. However, the blood-brain barrier is a significant barrier to achieving optimal brain concentration through oral, transdermal, and intravenous routes of administration. The intranasal route with nanocarrier-based formulations has shown potential for managing Parkinsonism disorder (PD). Direct delivery to the brain through the intranasal route is possible via the olfactory and trigeminal pathways using drug-loaded nanotechnology-based drug delivery systems. The critical analysis of reported works demonstrates dose reduction, brain targeting, safety, effectiveness, and stability for drug-loaded nanocarriers. The important aspects of intranasal drug delivery, PD details, and nanocarrier-based intranasal formulations in PD management with a discussion of physicochemical characteristics, cell line studies, and animal studies are the major topics in this review. Patent reports and clinical investigations are summarized in the last sections.

Bi-directional nasal drug delivery systems: A scoping review of nasal particle deposition patterns and clinical application

Objectives

To compare the deposition patterns within the nasal cavity between the bi-directional and unilateral nasal delivery systems. And to summarize the clinical application of the bi-directional nasal drug delivery devices.

Data source

PubMed, Cochrane Library, Embase, and Web of Science databases.

Methods

A scoping review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). We included studies exploring patterns and influencing factors of particle depositions within the nasal cavity among patients, healthy controls, and nose cast models using the bi-directional and unilateral nasal delivery system. The clinical application of the bi-directional delivery devices was also summarized.

Results

A total of 24 studies were included in this review. Bi-directional nasal delivery systems utilize forced exhalation to power the delivery of drugs to deeper areas of the nasal cavity and paranasal sinuses. Unilateral nasal delivery systems included traditional liquid spray pumps, the aerosol mask system, nebulization, and conventional nasal inhalation. Compared with unilateral delivery systems, the bi-directional nasal delivery system provided a more extensive and efficient nasal deposition in the nasal cavity, especially in the olfactory cleft, without lung deposition. Several parameters, including particle size, pulsatile flow, and nasal geometry, could significantly influence nasal deposition. The bi-directional nasal delivery system enables better delivery of steroids or sumatriptan to the sinonasal cavity's high and deep target sites. This bi-directional delivery device demonstrated an effective and well-tolerated treatment that produced high drug utilization, rapid absorption, and sustained symptom improvement among patients with chronic rhinosinusitis (CRS) or migraine.

Conclusion

The bi-directional nasal drug delivery systems demonstrated significantly higher drug deposition in superior and posterior regions of the nasal cavity than unilateral nasal delivery systems. Further studies should explore its potential role in delivering drugs to the olfactory cleft among patients with olfactory disorders and central nervous system diseases.

Level of evidence

N/A.

What Are the Key Anatomical Features for the Success of Nose-to-Brain Delivery? A Study of Powder Deposition in 3D-Printed Nasal Casts

Nose-to-brain delivery is a promising way to improve the treatment of central nervous system disorders, as it allows the bypassing of the blood-brain barrier. However, it is still largely unknown how the anatomy of the nose can influence the treatment outcome. In this work, we used 3D printing to produce nasal replicas based on 11 different CT scans presenting various anatomical features. Then, for each anatomy and using the Design of Experiments methodology, we characterised the amount of a powder deposited in the olfactory region of the replica as a function of multiple parameters (choice of the nostril, device, orientation angle, and the presence or not of a concomitant inspiration flow). We found that, for each anatomy, the maximum amount of powder that can be deposited in the olfactory region is directly proportional to the total area of this region. More precisely, the results show that, whatever the instillation strategy, if the total area of the olfactory region is below 1500 mm2, no more than 25% of an instilled powder can reach this region. On the other hand, if the total area of the olfactory region is above 3000 mm2, the deposition efficiency reaches 50% with the optimal choice of parameters, whatever the other anatomical characteristics of the nasal cavity. Finally, if the relative difference between the areas of the two sides of the internal nasal valve is larger than 20%, it becomes important to carefully choose the side of instillation. This work, by predicting the amount of powder reaching the olfactory region, provides a tool to evaluate the adequacy of nose-to-brain treatment for a given patient. While the conclusions should be confirmed via in vivo studies, it is a first step towards personalised treatment of neurological pathologies.

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.

Chitosan-Based Thermogelling System for Nose-to-Brain Donepezil Delivery: Optimising Formulation Properties and Nasal Deposition Profile

Donepezil nasal delivery strategies are being continuously investigated for advancing therapy in Alzheimer's disease. The aim of this study was to develop a chitosan-based, donepezil-loaded thermogelling formulation tailored to meet all the requirements for efficient nose-to-brain delivery. A statistical design of the experiments was implemented for the optimisation of the formulation and/or administration parameters, with regard to formulation viscosity, gelling and spray properties, as well as its targeted nasal deposition within the 3D-printed nasal cavity model. The optimised formulation was further characterised in terms of stability, in vitro release, in vitro biocompatibility and permeability (using Calu-3 cells), ex vivo mucoadhesion (using porcine nasal mucosa), and in vivo irritability (using slug mucosal irritation assay). The applied research design resulted in the development of a sprayable donepezil delivery platform characterised by instant gelation at 34 °C and olfactory deposition reaching a remarkably high 71.8% of the applied dose. The optimised formulation showed prolonged drug release (t_1/2 about 90 min), mucoadhesive behaviour, and reversible permeation enhancement, with a 20-fold increase in adhesion and a 1.5-fold increase in the apparent permeability coefficient in relation to the corresponding donepezil solution. The slug mucosal irritation assay demonstrated an acceptable irritability profile, indicating its potential for safe nasal delivery. It can be concluded that the developed thermogelling formulation showed great promise as an efficient donepezil brain-targeted delivery system. Furthermore, the formulation is worth investigating in vivo for final feasibility confirmation.

Re-examining Naloxone Pharmacokinetics After Intranasal and Intramuscular Administration Using the Finite Absorption Time Concept

BACKGROUND AND OBJECTIVES

Naloxone for opioid overdose treatment can be administered by intravenous injection, intramuscular injection, or intranasal administration. Published data indicate differences in naloxone pharmacokinetics depending on the route of administration. The aim of this study was to analyze pharmacokinetic data in the same way that we recently successfully applied the concept of the finite absorption time in orally administered drug formulations.

METHODS

Using the model equations already derived, we performed least squares analysis on 24 sets of naloxone concentration in the blood as a function of time.

RESULTS

We found that intramuscular and intranasal administration can be described more accurately when considering zero-order absorption kinetics for finite time compared with classical first order absorption kinetics for infinite time.

CONCLUSIONS

One-compartment models work well for most cases. Two-compartment models provide better details, but have higher parameter uncertainties. The absorption duration can be determined directly from the model parameters and thus allow an easy comparison between the ways of administration. Furthermore, the precise site of injection for intramuscular delivery appears to make a difference in terms of the duration of the drug absorption.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

Integration of miRNA's Theranostic Potential with Nanotechnology: Promises and Challenges for Parkinson's Disease Therapeutics

Despite the wide research going on in Parkinson's disease (PD), the burden of PD still remains high and continues to increase. The current drugs available for the treatment of PD are only aimed at symptomatic control. Hence, research is mainly focused on identifying the novel therapeutic targets that can be effectively targeted in order to slow down or culminate the disease progression. Recently the role of microRNAs (miRNAs) in the regulation of various pathological mechanisms of PD has been thoroughly explored and many of them were found to be dysregulated in the biological samples of PD patients. These miRNAs can be used as diagnostic markers and novel therapeutic options to manage PD. The delivery of miRNAs to the target site in brain is a challenging job owing to their nature of degradability by endonucleases as well as poor blood brain barrier (BBB) permeability. Nanoparticles appear to be the best solution to effectively encase the miRNA in their core as well as cross the BBB to deliver them into brain. Functionalisation of these nanoparticles further enhances the site-specific delivery.

Air-liquid interface (ALI) impact on different respiratory cell cultures

The intranasal route has been receiving greater attention from the scientific community not only for systemic drug delivery but also for the treatment of pulmonary and neurological diseases. Along with it, drug transport and permeability studies across the nasal mucosa have exponentially increased. Nevertheless, the translation of data from in vitro cell lines to in vivo studies is not always reliable, due to the difficulty in generating an in vitro model that resembles respiratory human physiology. Among all currently available methodologies, the air-liquid interface (ALI) method is advantageous to promote cell differentiation and optimize the morphological and histological characteristics of airway epithelium cells. Cells grown under ALI conditions, in alternative to submerged conditions, appear to provide relevant input for inhalation and pulmonary toxicology and complement in vivo experiments. Different methodologies and a variety of materials have been used to induce ALI conditions in primary cells and numerous cell lines. Until this day, with only exploratory results, no consensus has been reached regarding the validation of the ALI method, hampering data comparison. The present review describes the most adequate cell models of airway epithelium and how these models are differently affected by ALI conditions. It includes the evaluation of cellular features before and after ALI, and the application of the method in primary cell cultures, commercial 3D primary cells, cell lines and stem-cell derived models. A variety of these models have been recently applied for pharmacological studies against severe acute respiratory syndrome-coronavirus(-2) SARS-CoV(-2), namely primary cultures with alveolar type II epithelium cells and organotypic 3D models. The herein compiled data suggest that ALI conditions must be optimized bearing in mind the type of cells (nasal, bronchial, alveolar), their origin and the objective of the study.

Lipid nanocapsules for the nose-to-brain delivery of the anti-inflammatory bioactive lipid PGD2-G

Here, prostaglandin D₂-glycerol ester (PGD₂-G) was selected to target neuroinflammation. As PGD₂-G is reported to have a short plasmatic half-life, we propose to use lipid nanocapsules (LNC) as vehicle to safely transport PGD₂-G to the central nervous system (CNS). PGD₂-G-loaded LNC (PGD₂-G-LNC) reduced pro-inflammatory cytokine expression in activated microglial cells, even so after crossing a primary olfactory cell monolayer. A single nasal administration of PGD₂-G-LNC in lipopolysaccharide (LPS)-treated mice reduced pro-inflammatory cytokine expression in the olfactory bulb. Coating LNC's surface with a cell-penetrating peptide, transactivator of transcription (TAT), increased its accumulation in the brain. Although TAT-coated PGD₂-G-LNC modestly exerted its anti-inflammatory effect in a mouse model of multiple sclerosis similar to free PGD₂-G after nasal administration, TAT-coated LNC surprisingly reduced the expression of pro-inflammatory chemokines in the CNS. These data propose LNC as an interesting drug delivery tool and TAT-coated PGD₂-G-LNC remains a good candidate, in need of further work.

Meta-Analysis: A Convenient Tool for the Choice of Nose-to-Brain Nanocarriers

OBJECTIVES

The intranasal route represents a high promising route of administration aiming for brain delivery. Yet, it represents one of the most difficult and complicated routes. Accordingly, scientists are in a continuous search for novel drug delivery vehicles such as the lipid and polymeric nanoparticles that are apt to enhance the bioavailability of the administered drugs to reach the brain. In this study, a certain number of publications were selected from different databases and literature. Meta-analysis studies using two different algorithms (DerSimonian-Laird and inverse variance) followed aiming to explore the published studies and confirm by evidence the superiority of nanocarriers in enhancing the brain bioavailability of various drugs. Furthermore, the quantitative comparison of lipid versus polymeric nanosystems was performed.

METHODS

The area under the curve (AUC) as an important pharmacokinetic parameter extracted from in vivo animal studies was designated as the "effect" in the performed meta-analysis after normalization. Forest plots were generated.

KEY FINDINGS AND CONCLUSIONS

The meta-analysis confirmed the augmentation of the AUC after the comparison with traditional preparations such as solutions and suspensions. Most importantly, lipid nanoparticles were proven to be significantly superior to the polymeric counterparts.

Application of Intranasal Administration in the Delivery of Antidepressant Active Ingredients

As a mental disease in modern society, depression shows an increasing occurrence, with low cure rate and high recurrence rate. It has become the most disabling disease in the world. At present, the treatment of depression is mainly based on drug therapy combined with psychological therapy, physical therapy, and other adjuvant therapy methods. Antidepressants are primarily administered peripherally (oral and intravenous) and have a slow onset of action. Antidepressant active ingredients, such as neuropeptides, natural active ingredients, and some chemical agents, are limited by factors such as the blood–brain barrier (BBB), first-pass metabolism, and extensive adverse effects caused by systemic administration. The potential anatomical link between the non-invasive nose–brain pathway and the lesion site of depression may provide a more attractive option for the delivery of antidepressant active ingredients. The purpose of this article is to describe the specific link between intranasal administration and depression, the challenges of intranasal administration, as well as studies of intranasal administration of antidepressant active ingredients.

Novel therapeutic interventions for combating Parkinson's disease and prospects of Nose-to-Brain drug delivery

Parkinson disease (PD) is a progressive neurodegenerative disorder prevalent mainly in geriatric population. While, L-DOPA remains one of the major choices for the therapeutic management of PD, various motor and non-motor manifestations complicate the management of PD. In the last two decades, exhaustive research has been carried out to explore novel therapeutic approaches for mitigating motor and non-motor symptoms of PD. These approaches majorly include receptor-based, anti-inflammatory, stem-cell and nucleic acid based. The major limitations of existing therapeutic interventions (of commonly oral route) are low efficacy due to low brain bioavailability and associated side effects. Nanotechnology has been exploited and has gained wide attention in the recent years as an approach for enhancement of bioavailability of various small molecule drugs in the brain. To address the challenges associated with PD therapy, nose-to-brain delivery utilizing nanomedicine-based approaches has been found to be encouraging in published evidence. Therefore, the present work summarises the major challenges and limitations with antiparkinsonian drugs, novel therapeutic interventions, and scope of nanomedicine-based nose-to-brain delivery in addressing the current challenges of antiparkinsonian therapy. The manuscript tries to sensitize the researchers for designing brain-targeted nanomedicine loaded with natural/synthetic scaffolds, biosimilars, and nucleic acids that can bypass the first-pass effect for the effective management of PD.

Nano-lipidic formulation and therapeutic strategies for Alzheimer's disease via intranasal route

AIM

The inability of drug molecules to cross the 'Blood-Brain Barrier' restrict the effective treatment of Alzheimer's disease. Lipid nanocarriers have proven to be a novel paradigm in brain targeting of bioactive by facilitating suitable therapeutic concentrations to be attained in the brain.

METHODS

The relevant information regarding the title of this review article was collected from the peer-reviewed published articles. Also, the physicochemical properties, and their in vitro and in vivo evaluations were presented in this review article.

RESULTS

Administration of lipid-based nano-carriers have abilities to target the brain, improve the pharmacokinetic and pharmacodynamics properties of drugs, and mitigate the side effects of encapsulated therapeutic active agents.

CONCLUSION

Unlike oral and other routes, the Intranasal route promises high bioavailability, low first-pass effect, better pharmacokinetic properties, bypass of the systemic circulation, fewer incidences of unwanted side effects, and direct delivery of anti-AD drugs to the brain via circumventing 'Blood-Brain Barrier'.

In Vitro Evaluation of Nasal Aerosol Depositions: An Insight for Direct Nose to Brain Drug Delivery

The nasal cavity is an attractive route for both local and systemic drug delivery and holds great potential for access to the brain via the olfactory region, an area where the blood–brain barrier (BBB) is effectively absent. However, the olfactory region is located at the roof of the nasal cavity and only represents ~5–7% of the epithelial surface area, presenting significant challenges for the deposition of drug molecules for nose to brain drug delivery (NTBDD). Aerosolized particles have the potential to be directed to the olfactory region, but their specific deposition within this area is confounded by a complex combination of factors, which include the properties of the formulation, the delivery device and how it is used, and differences in inter-patient physiology. In this review, an in-depth examination of these different factors is provided in relation to both in vitro and in vivo studies and how advances in the fabrication of nasal cast models and analysis of aerosol deposition can be utilized to predict in vivo outcomes more accurately. The challenges faced in assessing the nasal deposition of aerosolized particles within the paediatric population are specifically considered, representing an unmet need for nasal and NTBDD to treat CNS disorders.

Improving Drug Delivery for Alzheimer's Disease Through Nose-to-Brain Delivery Using Nanoemulsions, Nanostructured Lipid Carriers (NLC) and in situ Hydrogels

Current treatments for Alzheimer's disease (AD) attenuate the progression of symptoms and aim to improve the patient's quality of life. Licensed medicines are mostly for oral administration and are limited by the difficulty in crossing the blood-brain barrier (BBB). Here in, the nasal route has been explored as an alternative pathway that allows drugs to be directly delivered to the brain via the nasal cavity. However, clearance mechanisms in the nasal cavity impair the delivery of drugs to the brain and limit their bioavailability. To optimize nose-to-brain delivery, formulations of lipid-based nanosystems, namely nanoemulsions and nanostructured lipid carriers (NLC), formulated in situ gelling hydrogels have been proposed as approaches for nose-to-brain delivery. These formulations possess characteristics that facilitate drug transport directly to the brain, minimizing side effects and maximizing therapeutic benefits. It has been recommended that the manufacture of these drug delivery systems follows the quality by design (QbD) approach based on nasal administration requirements. This review provides an insight into the current knowledge of the AD, highlighting the need for an effective drug delivery to the brain. Considering the mounting interest in the use of nanoemulsions and NLC for nose-to-brain delivery, a description of drug transport pathways in the nasal cavity and the application of these nanosystems and their in situ hydrogels through the intranasal route are presented. Relevant preclinical studies are summarised, and the future prospects for the use of lipid-based nanosystems in the treatment of AD are emphasized.

Rufinamide-Loaded Chitosan Nanoparticles in Xyloglucan-Based Thermoresponsive In Situ Gel for Direct Nose to Brain Delivery

In 2004, the US FDA approved Rufinamide, an anti-epileptic drug under the brand name Banzel^®. In 2015, Banzel^® received approval for its use in pediatric patients (ages 1–4 years). Rufinamide shows low oral bioavailability due to a low dissolution rate resulting in less of the drug reaching the brain. This has led to the high dose and dosing frequency of Rufinamide. In this work, using the principle of design of experiments (DoE), we have formulated Rufinamide-loaded chitosan nanoparticles and suspended them in a solution of a thermoresponsive polymer–tamarind seed xyloglucan to form a nasal in situ gel for direct nose to brain delivery of Rufinamide. The nanoparticles were characterized for particle size, entrapment efficiency, zeta potential, and physical stability. The in situ gel formulations were characterized for rheological properties, stability, and in vivo plasma and brain pharmacokinetics. Pharmacokinetic parameters were computed for aqueous suspension of nanoparticles and in situ gelling formulation for nanoparticles and compared with the pharmacokinetic parameters of an aqueous suspension of plain Rufinamide. The percentage of direct transport efficiency (% DTE) and direct transport percentage (%DTP) values were calculated for all the formulations. The optimized nanoparticle formulation showed a size of 180 ± 1.5 nm, a zeta potential of 38.3 ± 1.5 mV, entrapment efficiency of 75 ± 2.0%, and drug loading of 11 ± 0.3%. The in situ gelling formulation of nanoparticles showed a solution to the gel transition temperature of 32°C. The %DTE values for aqueous suspension of nanoparticles and in situ gelling formulation for nanoparticles were 988.5 and 1177.3 and the %DTP values were 86.06 and 91.5 respectively.

A systematic review and meta-analysis of the association between clozapine and norclozapine serum levels and peripheral adverse drug reactions

RATIONALE

Clozapine is the most effective antipsychotic for treatment-refractory schizophrenia for reducing positive psychotic symptoms. It is associated with a reduction in hospitalisation and overall mortality. In spite of this, clozapine remains underutilised due to its complex adverse drug reaction (ADR) profile.

OBJECTIVE

This systematic review aims to investigate the association of clozapine and norclozapine serum levels, and peripheral ADRs.

METHODS

Studies were searched from four electronic databases (PubMed, EMBASE, PsycINFO and CINAHL) from inception to 12 June 2020. Studies were included if they had adult patients, provided data on steady-state trough clozapine or norclozapine levels and reported on clozapine-associated ADRs. Pregnant women, case reports and series were excluded.

RESULTS

A statistically significant correlation was found for clozapine serum levels and triglycerides (n = 70; r = 0.303, 95% CI 0.0119-0.546, p = 0.042), heart rate (n = 137; r = 0.269, 95% CI 0.0918-0.486, p = 0.035), and overall combined ADRs (n = 160; r = 0.264, 95% CI 0.110-0.405, p = 0.001), but not for absolute neutrophil count (n = 223; r = - 0.164, 95% CI - 0.529-0.253, p = 0.444) or total white cell count (n = 18; r = 0.0176, 95% CI - 0.203-0.237, p = 0.878). Interestingly, norclozapine serum levels were found to be statistically correlated to triglycerides (n = 120; r = 0.211, 95% CI 0.0305-0.378, p = 0.022), total cholesterol (n = 120; r = 0.272, 95% CI 0.0948-0.432, p = 0.003) and weight gain (n = 118; r = 0.208, 95% CI 0.0261-0.377, p = 0.025).

CONCLUSIONS

Heart rate, triglycerides and combined ADRs are significantly correlated with clozapine levels, and triglycerides, total cholesterol and weight gain with norclozapine levels. Future prospective, randomised controlled studies are needed to identify the cause-effect relationship between clozapine levels and peripheral ADRs.

Intranasal delivery of Naloxone-loaded solid lipid nanoparticles as a promising simple and non-invasive approach for the management of opioid overdose

Naloxone is an opioid receptor antagonist that can eradicate all pre-indications of the toxicity and inverse the opioid overdose. However, oral administration of naloxone offers limitations such as its extensive first-pass metabolism that results in poor therapeutic effects. In order to resolve this issue, we developed intranasal solid-lipid nanoparticles in which naloxone was incorporated for the higher brain disposition of naloxone with superior therapeutic effects for the reversal of toxicity of opioid overdose. The preparation of naloxone loaded solid-lipid nanoparticles was done by employing the solvent evaporation method. Later, the designed formulation was optimized by Quality by Design approach, specifically, Box-Behnken method. The composition of optimized formulation was Glyceryl monostearate as a solid lipid (40 mg), Pluronic127 (0.5%) and Tween 80 (0.1%) as a surfactant and co-surfactant, respectively. Furthermore, the characterization of optimized formulation was achieved in terms of particle size, PDI, zeta potential, entrapment efficiency, and drug loading which were 190.2 nm, 0.082, -16 mV, 95 ± 0.532% and 19.08 ± 0.106%, respectively. Afterwards, in vitro, ex vivo and in vivo experiments were performed in which higher drug release and superior drug uptake by nasal membrane were observed for naloxone-loaded solid-lipid nanoparticles, later it was confirmed by confocal microscopy of ex vivo nasal membrane tissue. The findings of gamma scintigraphy investigation exhibited better deposition of naloxone-loaded solid-lipid nanoparticles as compared to naloxone solution. Also, the better deposition of naloxone by gamma scintigraphy was further validated by the investigation through the biodistribution study. Additionally, the key findings of the pharmacokinetic study revealed C_max, T_max, AUC_0-t, AUC_0-∞, T_1/2 and K_e was found to be 163.95 ± 2.64 ng/ml, 240 ± 2.1 min, 17.75 ± 1.08 ng.hr/ml, 18.82 ± 2.51 ng.hr/ml, 70.71 ± 0.115 min, 0.098 ± 0.01 h^-1 respectively. Lastly, investigations such as weight variation and histopathological proved the plausible potential of naloxone-loaded solid-lipid nanoparticles in terms of safety as no toxicity was noticed even after the administration of the three-folds dose of the normal dose. Therefore, considering all these findings, it could be easy to say that these developed naloxone-loaded solid-lipid nanoparticles could be administrated via intranasal route and can act as successful novel nanoformulation for the effective treatment of opioid overdose.

Think Big, Start Small: How Nanomedicine Could Alleviate the Burden of Rare CNS Diseases

The complexity and organization of the central nervous system (CNS) is widely modulated by the presence of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB), which both act as biochemical, dynamic obstacles impeding any type of undesirable exogenous exchanges. The disruption of these barriers is usually associated with the development of neuropathologies which can be the consequence of genetic disorders, local antigenic invasions, or autoimmune diseases. These disorders can take the shape of rare CNS-related diseases (other than Alzheimer's and Parkinson's) which a exhibit relatively low or moderate prevalence and could be part of a potential line of treatments from current nanotargeted therapies. Indeed, one of the most promising therapeutical alternatives in that field comes from the development of nanotechnologies which can be divided between drug delivery systems and diagnostic tools. Unfortunately, the number of studies dedicated to treating these rare diseases using nanotherapeutics is limited, which is mostly due to a lack of interest from industrial pharmaceutical companies. In the present review, we will provide an overview of some of these rare CNS diseases, discuss the physiopathology of these disorders, shed light on how nanotherapies could be of interest as a credible line of treatment, and finally address the major issues which can hinder the development of efficient therapies in that area.

Nose-to-brain drug delivery mediated by polymeric nanoparticles: influence of PEG surface coating

Intranasal administration of mucus-penetrating nanoparticles is an emerging trend to increase drug delivery to the brain. In order to overcome rapid nasal mucociliary clearance, low epithelial permeation, and local enzymatic degradation, we investigated the influence of PEGylation on nose-to-brain delivery of polycaprolactone (PCL) nanoparticles (PCL-NPs) encapsulating bexarotene, a potential neuroprotective compound. PEGylation with 1, 3, 5, and 10% PCL-PEG did not affect particle diameter or morphology. Upon incubation with artificial nasal mucus, only 5 and 10% of PCL-PEG coating were able to ensure NP stability and homogeneity in mucus. Rapid mucus-penetrating ability was observed for 98.8% of PCL-PEG_5% NPs and for 99.5% of PCL-PEG_10% NPs. Conversely, the motion of non-modified PCL-NPs was markedly slower. Fluorescence microscopy showed that the presence of PEG on NP surface did not reduce their uptake by RMPI 2650 cells. Fluorescence tomography images evidenced higher translocation into the brain for PCL-PEG_5% NPs. Bexarotene loaded into PCL-PEG_5% NPs resulted in area under the curve in the brain (AUC_brain) 3 and 2-fold higher than that for the drug dispersion and for non-PEGylated NPs (p < 0.05), indicating that approximately 4% of the dose was directly delivered to the brain. Combined, these results indicate that PEGylation of PCL-NPs with PCL-PEG_5% is able to reduce NP interactions with the mucus, leading to a more efficient drug delivery to the brain following intranasal administration. Graphical abstract.