Tailoring Formulations for Intranasal Nose-to-Brain Delivery: A Review on Architecture, Physico-Chemical Characteristics and Mucociliary Clearance of the Nasal Olfactory Mucosa

Current Nanoparticle Approaches in Nose to Brain Drug Delivery and Anticancer Therapy - A Review

Nanoparticles (NPs) are unique may be organic or inorganic, play a vital role in the development of drug delivery targeting the central nervous system (CNS). Intranasal drug delivery has shown to be an efficient strategy with attractive application for drug delivery to the CNS related diseases, such as Parkinson's disease, Alzheimer 's disease and brain solid tumors. Blood brain barrier (BBB) and blood-cerebrospinal fluid barriers are natural protective hindrances for entry of drug molecules into the CNS. Nanoparticles exhibit excellent intruding capacity for therapeutic agents and overcome protective barriers. By using nanotechnology based NPs targeted, drug delivery can be improved across BBB with discharge drugs in a controlled manner. NPs confer safe from degradation phenomenon. Several kinds of NPs are used for nose to the brain (N2B) enroute, such as lipidemic nanoparticles, polymeric nanoparticles, inorganic NPs, solid lipid NPs, dendrimers. Among them, popular lipidemic and polymeric NPs are discussed, and their participation in anti-cancer activity has also been highlighted in this review.

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.

Transmucosal drug administration as an alternative route in palliative and end-of-life care during the COVID-19 pandemic

The Coronavirus disease 2019 (COVID-19) pandemic has led to a surge in need for alternative routes of administration of drugs for end of life and palliative care, particularly in community settings. Transmucosal routes include intranasal, buccal, sublingual and rectal. They are non-invasive routes for systemic drug delivery with the possibility of self-administration, or administration by family caregivers. In addition, their ability to offer rapid onset of action with reduced first-pass metabolism make them suitable for use in palliative and end-of-life care to provide fast relief of symptoms. This is particularly important in COVID-19, as patients can deteriorate rapidly. Despite the advantages, these routes of administration face challenges including a relatively small surface area for effective drug absorption, small volume of fluid for drug dissolution and the presence of a mucus barrier, thereby limiting the number of drugs that are suitable to be delivered through the transmucosal route. In this review, the merits, challenges and limitations of each of these transmucosal routes are discussed. The goals are to provide insights into using transmucosal drug delivery to bring about the best possible symptom management for patients at the end of life, and to inspire scientists to develop new delivery systems to provide effective symptom management for this group of patients.

Impact of Glycosylation and Species Origin on the Uptake and Permeation of IgGs through the Nasal Airway Mucosa

Although we have recently reported the involvement of neonatal Fc receptor (FcRn) in intranasal transport, the transport mechanisms are far from being elucidated. Ex vivo porcine olfactory tissue, primary cells from porcine olfactory epithelium (OEPC) and the human cell line RPMI 2650 were used to evaluate the permeation of porcine and human IgG antibodies through the nasal mucosa. IgGs were used in their wild type and deglycosylated form to investigate the impact of glycosylation. Further, the expression of FcRn and Fc-gamma receptor (FCGR) and their interaction with IgG were analyzed. Comparable permeation rates for human and porcine IgG were observed in OEPC, which display the highest expression of FcRn. Only traces of porcine IgGs could be recovered at the basolateral compartment in ex vivo olfactory tissue, while human IgGs reached far higher levels. Deglycosylated human IgG showed significantly higher permeation in comparison to the wild type in RPMI 2650 and OEPC, but insignificantly elevated in the ex vivo model. An immunoprecipitation with porcine primary cells and tissue identified FCGR2 as a potential interaction partner in the nasal mucosa. Glycosylation sensitive receptors appear to be involved in the uptake, transport, but also degradation of therapeutic IgGs in the airway epithelial layer.

Preparation of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Drug Delivery and the Effects of Preparation Parameters of Solvent Injection Method

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have emerged as potential drug delivery systems for various applications that are produced from physiological, biodegradable, and biocompatible lipids. The methods used to produce SLNs and NLCs have been well investigated and reviewed, but solvent injection method provides an alternative means of preparing these drug carriers. The advantages of solvent injection method include a fast production process, easiness of handling, and applicability in many laboratories without requirement of complicated instruments. The effects of formulations and process parameters of this method on the characteristics of the produced SLNs and NLCs have been investigated in several studies. This review describes the methods currently used to prepare SLNs and NLCs with focus on solvent injection method. We summarize recent development in SLNs and NLCs production using this technique. In addition, the effects of solvent injection process parameters on SLNs and NLCs characteristics are discussed.

Challenges and Opportunities of Deferoxamine Delivery for Treatment of Alzheimer's Disease, Parkinson's Disease, and Intracerebral Hemorrhage

Deferoxamine mesylate (DFO) is an FDA-approved, hexadentate iron chelator routinely used to alleviate systemic iron burden in thalassemia major and sickle cell patients. Iron accumulation in these disease states results from the repeated blood transfusions required to manage these conditions. Iron accumulation has also been implicated in the pathogenesis of Alzheimer's disease (AD), Parkinson's disease (PD), and secondary injury following intracerebral hemorrhage (ICH). Chelation of brain iron is thus a promising therapeutic strategy for improving behavioral outcomes and slowing neurodegeneration in the aforementioned disease states, though the effectiveness of DFO treatment is limited on several accounts. Systemically administered DFO results in nonspecific toxicity at high doses, and the drug's short half-life leads to low patient compliance. Mixed reports of DFO's ability to cross the blood-brain barrier (BBB) also appear in literature. These limitations necessitate novel DFO formulations prior to the drug's widespread use in managing neurodegeneration. Herein, we discuss the various dosing regimens and formulations employed in intranasal (IN) or systemic DFO treatment, as well as the physiological and behavioral outcomes observed in animal models of AD, PD, and ICH. The clinical progress of chelation therapy with DFO in managing neurodegeneration is also evaluated. Finally, the elimination of intranasally administered particles via the glymphatic system and efflux transporters is discussed. Abundant preclinical evidence suggests that intranasal DFO treatment improves memory retention and behavioral outcome in rodent models of AD, PD, and ICH. Several other biochemical and physiological metrics, such as tau phosphorylation, the survival of tyrosine hydroxylase-positive neurons, and infarct volume, are also positively affected by intranasal DFO treatment. However, dosing regimens are inconsistent across studies, and little is known about brain DFO concentration following treatment. Systemic DFO treatment yields similar results, and some complex formulations have been developed to improve permeability across the BBB. However, despite the success in preclinical models, clinical translation is limited with most clinical evidence investigating DFO treatment in ICH patients, where high-dose treatment has proven dangerous and dosing regimens are not consistent across studies. DFO is a strong drug candidate for managing neurodegeneration in the aging population, but before it can be routinely implemented as a therapeutic agent, dosing regimens must be standardized, and brain DFO content following drug administration must be understood and controlled via novel formulations.

Chitosan Hydrogel Doped with PEG-PLA Nanoparticles for the Local Delivery of miRNA-146a to Treat Allergic Rhinitis

To prepare a binary formulation delivering miRNA-146 and evaluate a nucleic acid nasal delivery system by investigating its pharmacodynamic effects in allergic rhinitis. The gel/NPs/miR-146a thermosensitive in situ chitosan hydrogel carrying a nucleic acid was prepared and evaluated for its characteristics, including temperature sensitivity, gel strength, mucosal adhesion and drug release profile. After nasal administration of the formulation to ovalbumin-sensitized rats, the treatment of allergic rhinitis was verified by assessing nasal symptoms, hematology, hematoxylin-eosin (HE) staining and immunohistochemistry. Western Blot(WB) was used to analyze nasal inflammatory factors as well as miRNA-146-related factors, and the miR146 expression level was measured by PCR. Subsequently, the effects of the gel/NPs/miR-146a binary formulation were evaluated for the nasal delivery of nucleic acids in rhinitis therapy. The prepared binary formulation quickly formed a gel in the nasal cavity at a temperature of 34 °C with good mucosal adhesion, which delivered nucleic acids into the nasal mucosa stably and continuously. Gel/NPs/miR-146a was able to sustain the delivery of miRNA into the mucosa after nasal administration. When compared with the monolithic formulations, the gel/NPs/miR-146a binary formulation performed better regarding its nucleic acid delivery ability and pharmacodynamic effects. The gel/NPs/miR-146a binary preparation has a suitable nasal mucosal drug delivery ability and has a positive pharmacodynamic effect for the treatment of ovalbumin-induced rhinitis in rats. It can serve as a potential nucleic acid delivery platform for the treatment of allergic rhinitis.

The uses of resveratrol for neurological diseases treatment and insights for nanotechnology based-drug delivery systems

Neurological disorders have been growing in recent years and are highly prevalent globally. Resveratrol (RES) is a natural product from plant sources such as grape skins. This compound has shown biological activity in many diseases, in particular, those that act on the central nervous system. The mechanism of action and the key points in neurological disorders were described and show the targeted mechanism of action. Due to the insolubility of this compound; the use of nanotechnology-based systems has been proposed for the incorporation of RES and RES-loaded nanocarriers have been designed for intranasal administration, oral or parenteral routes to deliver it to the brain. In general, these nanosystems have shown to be effective in many studies, pharmacological and pharmacokinetic assays, as well as some cell studies. The outcomes show that RES has been reported in human clinical trials for some neurological diseases, although no studies were performed in humans using nanocarriers, animal and/or cellular models have been reported to show good results regarding therapeutics on neurological diseases. Thus, the use of this nutraceutical has shown true for neurological diseases and its loading into nanocarriers displaying good results on the stability, delivery and targeting to the brain.

Chitosan-coated PLGA nanoparticles for the nasal delivery of ropinirole hydrochloride: In vitro and ex vivo evaluation of efficacy and safety

Nose-to-brain delivery is an attractive route for direct drug delivery to the central nervous system (CNS), avoiding hepatic first-pass metabolism and solving blood-brain barrier passage issues. Therefore, the aim of the present study was the development of PLGA and PLGA/chitosan (chit) nanoparticles (NPs) with mucoadhesive properties, able to encapsulate ropinirole hydrochloride (RH), an anti-Parkinsonian dopaminergic agonist, and suitable to promote RH delivery across the nasal mucosa. NPs produced by nanoprecipitation showed spherical shape and a mean average size of 98.8 nm and 468.0 nm (PLGA and PLGA/chit, respectively). RH loaded PLGA/chit NPs showed a complete release of the drug in simulated nasal electrolyte solution (SNES) over the period of 24 h and increased the permeation of RH through sheep nasal mucosa by 3.22-fold in comparison to PLGA NPs. None of RH loaded NPs induced hemolysis in whole blood or the production of reactive oxygen species (ROS) in Raw 264.7 cells. On their turn, PLGA/chit NPs decreased cell viability of Raw 264.7 cells and Peripheral Blood Mononuclear Cells (PBMCs) in a concentration-dependent manner. These results revealed that, particularly PLGA/chit NPs, could be a valuable carrier for the delivery of RH to the CNS, opening a new path for Parkinson's disease therapy.

Investigation of Cytotoxicity and Cell Uptake of Cationic Beta-Cyclodextrins as Valid Tools in Nasal Delivery

Cyclodextrin polymers have high applicability in pharmaceutical formulations due to better biocompatibility, solubility enhancement, loading capacity and controlled drug release than their parent, cyclodextrins. The cytotoxicity and cell uptake of new cationic beta-cyclodextrin monomers and polymers were evaluated as suitable materials for nasal formulations and their protective effects on cells exposed to hydrogen peroxide were studied. PC12 and CACO-2 cells were selected as the neuronal- and epithelial-type cells, respectively, to mimic the structure of respiratory and olfactory epithelia of the nasal cavity. All cationic beta-cyclodextrin polymers tested showed dose- and time-dependent toxicity; nevertheless, at 5 µM concentration and 60 min of exposure, the quaternary-ammonium-beta-cyclodextrin soluble polymer could be recognized as nontoxic. Based on these results, a fluorescently labelled quaternary-ammonium-beta-cyclodextrin monomer and polymer were selected for uptake studies in CACO-2 cells. The monomeric and polymeric beta-cyclodextrins were internalized in the cytoplasm of CACO-2 cells; the cationic monomer showed higher permeability than the hydroxypropyl-beta-cyclodextrin, employed as comparison. Therefore, these cationic beta-cyclodextrins showed potential as excipients able to improve the nasal absorption of drugs. Furthermore, amino-beta-cyclodextrin and beta-cyclodextrin soluble polymers were able to reduce oxidative damage in PC12 and CACO-2 cells and thus could be studied as bioactive carriers or potential drugs for cell protection against oxidative stress.

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.

A CGRP receptor antagonist peptide formulated for nasal administration to treat migraine

OBJECTIVES

To investigate the formulation of the peptide-based antagonist (³⁴ Pro,³⁵ Phe)CGRP_27-37 , of the human calcitonin gene-related peptide (CGRP) receptor as a potential nasally delivered migraine treatment.

METHODS

Peptide sequences were prepared using automated methods and purified by preparative HPLC. Their structure and stability were determined by LC-MS. Antagonist potency was assessed by measuring CGRP-stimulated cAMP accumulation in SK-N-MC, cells and in CHO cells overexpressing the human CGRP receptor. In vivo activity was tested in plasma protein extravasation (PPE) studies using Evans blue dye accumulation. Peptide-containing chitosan microparticles were prepared by spray drying.

KEY FINDINGS

(³⁴ Pro,³⁵ Phe)CGRP_27-37 exhibited a 10-fold increased affinity compared to αCGRP_27-37 . Administration of (³⁴ Pro,³⁵ Phe)CGRP_27-37 to mice led to a significant decrease in CGRP-induced PPE confirming antagonistic properties in vivo. There was no degradation of (³⁴ Pro,³⁵ Phe)CGRP_27-37 and no loss of antagonist potency during formulation and release from chitosan microparticles.

CONCLUSIONS

(³⁴ Pro,³⁵ Phe)CGRP_27-37 is a potent CGRP receptor antagonist both in vitro and in vivo, and it can be formulated as a dry powder with no loss of activity indicating its potential as a nasally formulated anti-migraine medicine.

Disentangling the Hypothesis of Host Dysosmia and SARS-CoV-2: The Bait Symptom That Hides Neglected Neurophysiological Routes

The respiratory condition COVID-19 arises in a human host upon the infection with SARS-CoV-2, a coronavirus that was first acknowledged in Wuhan, China, at the end of December 2019 after its outbreak of viral pneumonia. The full-blown COVID-19 can lead, in susceptible individuals, to premature death because of the massive viral proliferation, hypoxia, misdirected host immunoresponse, microthrombosis, and drug toxicities. Alike other coronaviruses, SARS-CoV-2 has a neuroinvasive potential, which may be associated with early neurological symptoms. In the past, the nervous tissue of patients infected with other coronaviruses was shown to be heavily infiltrated. Patients with SARS-CoV-2 commonly report dysosmia, which has been related to the viral access in the olfactory bulb. However, this early symptom may reflect the nasal proliferation that should not be confused with the viral access in the central nervous system of the host, which can instead be allowed by means of other routes for spreading in most of the neuroanatomical districts. Axonal, trans-synaptic, perineural, blood, lymphatic, or Trojan routes can gain the virus multiples accesses from peripheral neuronal networks, thus ultimately invading the brain and brainstem. The death upon respiratory failure may be also associated with the local inflammation- and thrombi-derived damages to the respiratory reflexes in both the lung neuronal network and brainstem center. Beyond the infection-associated neurological symptoms, long-term neuropsychiatric consequences that could occur months after the host recovery are not to be excluded. While our article does not attempt to fully comprehend all accesses for host neuroinvasion, we aim at stimulating researchers and clinicians to fully consider the neuroinvasive potential of SARS-CoV-2, which is likely to affect the peripheral nervous system targets first, such as the enteric and pulmonary nervous networks. This acknowledgment may shed some light on the disease understanding further guiding public health preventive efforts and medical therapies to fight the pandemic that directly or indirectly affects healthy isolated individuals, quarantined subjects, sick hospitalized, and healthcare workers.

Suitability and functional characterization of two Calu-3 cell models for prediction of drug permeability across the airway epithelial barrier

The Calu-3 cell line has been largely investigated as a physiological and pharmacological model of the airway epithelial barrier. Its suitability for prediction of drug permeability across the airway epithelia, however, has not been yet evaluated by using large enough set of model drugs. We evaluated two Calu-3 cell models (air-liquid and liquid-liquid) for drug permeability prediction based on the recent regulatory guidelines on showing suitability of in vitro permeability methods for drug permeability classification. Bidirectional permeability assays using 22 model drugs and several zero permeability markers, as well as using ABC transporter substrates were conducted. Functional activity of P-gp, but not of BCRP was revealed. The potential of the Calu-3 cells to be used as a model of the nasal epithelial barrier, despite their different anatomical origin, has been demonstrated by the obtained excellent correlation with the fully differentiated 3D human nasal epithelial model (MucilAir™) for 11 model drugs, as well as by the good correlation obtained with the human nasal epithelial cell line RPMI 2650. In addition, the permeability values determined in the two Calu-3 models correlated well with the intestinal permeability model Caco-2.

Effects of Intranasal Epinephrine on Cerebrospinal Fluid Epinephrine Pharmacokinetics, Nasal Mucosa, Plasma Epinephrine Pharmacokinetics, and Cardiovascular Changes

PURPOSE

We aimed to assess intranasal (IN) epinephrine effects on cerebrospinal fluid (CSF) absorption, nasal mucosa quality, plasma epinephrine pharmacokinetics (PK), and cardiovascular changes in dogs.

METHODS

CSF epinephrine concentration was measured and nasal mucosa quality was evaluated after IN epinephrine 4 mg and one or two 4 mg doses (21 min apart), respectively. Maximum plasma concentration [C_max], time to C_max [T_max], area under the curve from 0 to 120 min [AUC_0-120], and cardiovascular effects were evaluated after epinephrine IN (4 and 5 mg) and intramuscular (IM; 0.3 mg). Clinical observations were assessed.

RESULTS

After epinephrine IN, there were no changes in CSF epinephrine or nasal mucosa. C_max, T_max, and AUC_1-120 were similar following epinephrine IN and IM. Epinephrine IN versus IM increased plasma epinephrine at 1 min (mean ± SEM, 1.15 ± 0.48 for 4 mg IN and 1.7 ± 0.72 for 5 mg IN versus 0.47 ± 0.11 ng/mL for 0.3 mg IM). Epinephrine IN and IM produced similar heart rate and ECG results. Clinical observations included salivation and vomiting.

CONCLUSIONS

Epinephrine IN did not alter CSF epinephrine or nasal tissue and had similar cardiovascular effects as epinephrine IM. Epinephrine IN rapidly increased plasma epinephrine concentration versus epinephrine IM.

Optimization of Curcumin Nanocrystals as Promising Strategy for Nose-to-Brain Delivery Application

Intranasal (IN) drug delivery is recognized to be an innovative strategy to deliver drugs to the Central Nervous System. One of the main limitations of IN dosing is the low volume of drug that can be administered. Accordingly, two requirements are necessary: the drug should be active at a low dosage, and the drug solubility in water must be high enough to accommodate the required dose. Drug nanocrystals may overcome these limitations; thus, curcumin was selected as a model drug to prepare nanocrystals for potential IN administration. With this aim, we designed curcumin nanocrystals (NCs) by using Box Behnken design. A total of 51 formulations were prepared by the sonoprecipitation method. Once we assessed the influence of the independent variables on nanocrystals' mean diameter, the formulation was optimized based on the desirability function. The optimized formulation was characterized from a physico-chemical point of view to evaluate the mean size, zeta potential, polidispersity index, pH, osmolarity, morphology, thermotropic behavior and the degree of crystallinity. Finally, the cellular uptake of curcumin and curcumin NCs was evaluated on Olfactory Ensheathing Cells (OECs). Our results showed that the OECs efficiently took up the NCs compared to the free curcumin, showing that NCs can ameliorate drug permeability.

Nose-to-brain delivery of antipsychotics using nanotechnology: a review

INTRODUCTION

Orally-administered antipsychotics are effective in the management of psychosis-related disorders although generation-specific adverse drug reactions (ADRs) significantly hinder clinical outcomes, driven by issues such as patient non-compliance. Direct nose-to-brain (N2B) delivery of antipsychotics via the olfactory epithelium could avert peripheral ADRs by maximizing cerebral drug concentrations, and reducing drug levels in the periphery. However, there exist physicochemical challenges related to psychotropic drugs, alongside biochemical barriers associated with targeting the olfactory region. Nanotechnological approaches present a viable strategy for the development of intranasal antipsychotic formulations where drug stability, mucosal absorption and cerebrospinal fluid (CSF)-bioavailability can be optimized.

AREAS COVERED

This review explores the unique anatomical features of the nasal cavity as a pathway for antipsychotic drug delivery to the brain. Nanocarrier-based approaches to encapsulate antipsychotics, and enhance stability, absorption and bioavailability are explored. The aim of this review is to determine current knowledge gaps for direct N2B psychotropic drug delivery, and identify clinically acceptable strategies to overcome them.

EXPERT OPINION

The olfactory epithelium may be the most effective and direct administration route for antipsychotic delivery to the central nervous system (CNS). This research is novel and has the potential to revolutionize the mode of delivery of neurological medicines to the CNS in the future.

Primary Studies on Construction and Evaluation of Ion-Sensitive in situ Gel Loaded with Paeonol-Solid Lipid Nanoparticles for Intranasal Drug Delivery

BACKGROUND

Paeonol (PAE) is a potential central neuroprotective agent with poor water solubility and rapid metabolism in vivo. The key to improve the clinical application of PAE in the treatment of neurodegenerative diseases is to improve the brain delivery of it. The purpose of this study was to construct a paeonol-solid lipid nanoparticles-in situ gel (PAE-SLNs-ISG) drug delivery system based on nose-brain transport pathway.

MATERIALS AND METHODS

In this study, the stability of PAE in simulated biological samples was studied firstly in order to clarify the reasons for low oral bioavailability. Paeonol-solid lipid nanoparticles (PAE-SLNs) were prepared by high-temperature emulsification-low-temperature curing combined with ultrasound. The PAE-SLNs-ISG drug delivery system was constructed, and related formulation optimization, preparation characterization, cell evaluation and in vivo evaluation were performed.

RESULTS

The metabolic mechanism of PAE incubated in the liver microsomes metabolic system was in accordance with the first-order kinetics, and the half-life was 0.23 h. PAE-SLNs were polyhedral or spherical particles with good dispersion and the particle size was 166.79 nm ± 2.92 nm. PAE-SLNs-ISG solution was a Newtonian fluid with a viscosity of 44.36 mPa · S ± 2.89 mPa · S. The viscosity of PAE-SLNs-ISG gel was 1542.19 mPa · S ± 19.30 mPa · S, and the rheological evaluation showed that the gel was a non-Newtonian pseudoplastic fluid with shear thinning, thixotropy and yield value. The release mechanism of PAE from PAE-SLNs was drug diffusion; the release mechanism of PAE from PAE-SLNs-ISG was a synergistic effect of skeleton erosion and drug diffusion. The cell viabilities of PAE-SLNs and PAE-SLNs-ISG in the concentration range of 0.001 µg/mL to 10 µg/mL were higher than 90%, showing a low level of cytotoxicity. The geometric mean fluorescent intensities of RPMI 2650 cells incubated with fluorescein isothiocyanate-solid lipid nanoparticles (FITC-SLNs) for 1 h, 4 h and 6 h were 1841 ± 24, 2261 ± 27 and 2757 ± 22, respectively. Cyanine7 NHS ester-solid lipid nanoparticles-in situ gel (Cy7-SLNs-ISG) accumulated effectively in the brain area after administration through the olfactory area, and the fluorescence response was observed in olfactory bulb, cerebellum and striatum.

CONCLUSION

SLNs-ISG nose-brain drug delivery system can effectively deliver SLNs to brain regions, and it is a potentially effective strategy to realize the brain region delivery of PAE.

Nose to brain drug delivery - A promising strategy for active components from herbal medicine for treating cerebral ischemia reperfusion

Cerebral ischemia reperfusion injury (CIRI), one of the major causes of death from stroke in the world, not only causes tremendous damage to human health, but also brings heavy economic burden to society. Current available treatments for CIRI, including mechanical therapies and drug therapies, are often accompanied by significant side-effects. Therefore, it is necessary to discovery new strategies for treating CIRI. Many studies have confirmed that the herbal medicine has the advantages of abundant resources, good curative effect and little side effects, which can be used as potential drug for treatment of CIRI through multiple targets. It's known that oral administration commonly has low bioavailability, and injection administration is inconvenient and unsafe. Many drugs can't delivery to brain through routine pathways due to the blood-brain-barrier (BBB). Interestingly, increasing evidences have suggested the nasal administration is a potential direct route to transport drug into brain avoiding the BBB and has the characteristics of high bioavailability for treating brain diseases. Therefore, intranasal administration can be treated as an alternative way to treat brain diseases. In the present review, effective methods to treat CIRI by using active ingredients derived from herbal medicine through nose to brain drug delivery (NBDD) are updated and discussed, and some related pharmacological mechanisms have also been emphasized. Our present study would be beneficial for the further drug development of natural agents from herbal medicines via NBDD.

Pharmacotechnical Development of a Nasal Drug Delivery Composite Nanosystem Intended for Alzheimer's Disease Treatment

Direct nose-to-brain delivery has been raised as a non-invasive powerful strategy to deliver drugs to the brain bypassing the blood-brain barrier (BBB). This study aimed at preparing and characterizing an innovative composite formulation, associating the liposome and hydrogel approaches, suitable for intranasal administration. Thermosensitive gel formulations were obtained based on a mixture of two hydrophilic polymers (Poloxamer 407, P407 and Poloxamer 188, P188) for a controlled delivery through nasal route via liposomes of an active pharmaceutical ingredient (API) of potential interest for Alzheimer’s disease. The osmolarity and the gelation temperature (T° sol-gel) of formulations, defined in a ternary diagram, were investigated by rheometry and visual determination. Regarding the issue of assays, a mixture composed of P407/P188 (15/1%, w/w) was selected for intranasal administration in terms of T° sol-gel and for the compatibility with the olfactory mucosal (280 ± 20 mOsmol, pH 6). Liposomes of API were prepared by the thin film hydration method. Mucoadhesion studies were performed by using mucin disc, and they showed the good natural mucoadhesive characteristics of in situ gel formulations, which increased when liposomes were added. The study demonstrated successful pharmacotechnical development of a promising API-loaded liposomes in a thermosensitive hydrogel intended for nasal Alzheimer’s disease treatment.

Imaging of intranasal drug delivery to the brain

Intranasal (IN) delivery is a rapidly developing area for therapies with great potential for the treatment of central nervous system (CNS) diseases. Moreover, in vivo imaging is becoming an important part of therapy assessment, both clinically in humans and translationally in animals. IN drug delivery is an alternative to systemic administration that uses the direct anatomic pathway between the olfactory/trigeminal neuroepithelium of the nasal mucosa and the brain. Several drugs have already been approved for IN application, while others are undergoing development and testing. To better understand which imaging modalities are being used to assess IN delivery of therapeutics, we performed a literature search with the key words "Intranasal delivery" and "Imaging" and summarized these findings in the current review. While this review does not attempt to be fully comprehensive, we intend for the examples provided to allow a well-rounded picture of the imaging tools available to assess IN delivery, with an emphasis on the nose-to-brain delivery route. Examples of in vivo imaging, for both humans and animals, include magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), gamma scintigraphy and computed tomography (CT). Additionally, some in vivo optical imaging modalities, including bioluminescence and fluorescence, have been used more in experimental testing in animals. In this review, we introduce each imaging modality, how it is being utilized and outline its strengths and weaknesses, specifically in the context of IN delivery of therapeutics to the brain.

Niosome-Based Approach for In Situ Gene Delivery to Retina and Brain Cortex as Immune-Privileged Tissues

Non-viral vectors have emerged as a promising alternative to viral gene delivery systems due to their safer profile. Among non-viral vectors, recently, niosomes have shown favorable properties for gene delivery, including low toxicity, high stability, and easy production. The three main components of niosome formulations include a cationic lipid that is responsible for the electrostatic interactions with the negatively charged genetic material, a non-ionic surfactant that enhances the long-term stability of the niosome, and a helper component that can be added to improve its physicochemical properties and biological performance. This review is aimed at providing recent information about niosome-based non-viral vectors for gene delivery purposes. Specially, we will discuss the composition, preparation methods, physicochemical properties, and biological evaluation of niosomes and corresponding nioplexes that result from the addition of the genetic material onto their cationic surface. Next, we will focus on the in situ application of such niosomes to deliver the genetic material into immune-privileged tissues such as the brain cortex and the retina. Finally, as future perspectives, non-invasive administration routes and different targeting strategies will be discussed.

Nose-to-Brain Delivery

Nose-to-brain delivery represents a big challenge. In fact there is a large number of neurological diseases that require therapies in which the drug must reach the brain, avoiding the difficulties due to the blood-brain barrier (BBB) and the problems connected with systemic administration, such as drug bioavailability and side-effects. For these reasons the development of nasal formulations able to deliver the drug directly into the brain is of increasing importance. This Editorial regards the contributions present in the Special Issue "Nose-to-Brain Delivery".

Inhaled levodopa for intermittent treatment of OFF episodes in patients with Parkinson's disease

Introduction: Many patients with advanced Parkinson's disease (PD) have inadequate control of motor symptoms despite optimized treatment. Predictable and unpredictable OFF periods severely interfere with the quality of life. A drug that easily and rapidly reverts the OFF state is still needed. Subcutaneous apomorphine, the only approved drug for this indication, although efficacious, is not widely used probably due to its potential side effects and complicated administration.Levodopa is the most efficacious drug for the treatment of PD motor symptoms. However, issues related to the oral route and intestinal absorption in later disease stages render this route lengthy and inefficacious.Areas covered: Literature on the development of an inhaled formulation of levodopa has been reviewed. Significant advances in the field of pulmonary delivery systems and in dry powders have enabled the development of a new formulation of levodopa that can be inhaled and adequate blood levels rapidly achieved, bypassing intestinal absorption. Several clinical trials have reported efficacy, safety, and tolerability data. Some pulmonary-related adverse events have been reported but are mostly mild.Expert opinion: This new way of administering levodopa is likely to be very welcome and may fill a gap for OFF rescue treatments, at least for some patients.

Progress and perspectives of brain-targeting lipid-based nanosystems via the nasal route in Alzheimer's disease

Since health care systems dedicate substantial resources to Alzheimer's disease (AD), it poses an increasing challenge to scientists and health care providers worldwide, especially that many decades of research in the medical field revealed no optimal effective treatment for this disease. The intranasal administration route seems to be a preferable route of anti-AD drug delivery over the oral one as it demonstrates an ability to overcome the related obstacles reflected in low bioavailability, limited brain exposure and undesired pharmacokinetics or side effects. This delivery route can bypass the systemic circulation through the intraneuronal and extraneuronal pathways, providing truly needleless and direct brain drug delivery of the therapeutics due to its large surface area, porous endothelial membrane, the avoidance of the first-pass metabolism, and ready accessibility. Among the different nano-carrier systems developed, lipid-based nanosystems have become increasingly popular and have proven to be effective in managing the common symptoms of AD when administered via the nose-to-brain delivery route, which provides an answer to circumventing the BBB. The design of such lipid-based nanocarriers could be challenging since many factors can contribute to the quality of the final product. Hence, according to the authors, it is recommended to follow the quality by design methodology from the early stage of development to ensure high product quality while saving efforts and costs. This review article aims to draw attention to the up-to-date findings in the field of lipid-based nanosystems and the potential role of developing such forms in the management of AD by means of the nose-to-brain delivery route, in addition to highlighting the significant role of applying QbD methodology in this development.

Respiratory syncytial virus tropism for olfactory sensory neurons in mice

The olfactory mucosa, where the first step of odor detection occurs, is a privileged pathway for environmental toxicants and pathogens toward the central nervous system. Indeed, some pathogens can infect olfactory sensory neurons including their axons projecting to the olfactory bulb allowing them to bypass the blood-brain barrier and reach the central nervous system (CNS) through the so-called olfactory pathway. The respiratory syncytial virus (RSV) is a major respiratory tract pathogen but there is growing evidence that RSV may lead to CNS impairments. However, the mechanisms involved in RSV entering into the CNS have been poorly described. In this study, we wanted to explore the capacity of RSV to reach the CNS via the olfactory pathway and to better characterize RSV cellular tropism in the nasal cavity. We first explored the distribution of RSV infectious sites in the nasal cavity by in vivo bioluminescence imaging and a tissue clearing protocol combined with deep-tissue imaging and 3D image analyses. This whole tissue characterization was confirmed with immunohistochemistry and molecular biology approaches. Together, our results provide a novel 3D atlas of mouse nasal cavity anatomy and show that RSV can infect olfactory sensory neurons giving access to the central nervous system by entering the olfactory bulb. Cover Image for this issue: doi: 10.1111/jnc.14765.

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.

Key for crossing the BBB with nanoparticles: the rational design

Central nervous system diseases are a heavy burden on society and health care systems. Hence, the delivery of drugs to the brain has gained more and more interest. The brain is protected by the blood-brain barrier (BBB), a selective barrier formed by the endothelial cells of the cerebral microvessels, which at the same time acts as a bottleneck for drug delivery by preventing the vast majority of drugs to reach the brain. To overcome this obstacle, drugs can be loaded inside nanoparticles that can carry the drug through the BBB. However, not all particles are able to cross the BBB and a multitude of factors needs to be taken into account when developing a carrier system for this purpose. Depending on the chosen pathway to cross the BBB, nanoparticle material, size and surface properties such as functionalization and charge should be tailored to fit the specific route of BBB crossing.

Nose to brain delivery of antiretroviral drugs in the treatment of neuroAIDS

NeuroAIDS (Neuro Acquired Immunodeficiency Syndrome) or HIV (Human Immunodeficiency Virus) associated neuronal abnormality is continuing to be a significant health issue among AIDS patients even under the treatment of combined antiretroviral therapy (cART). Injury and damage to neurons of the brain are the prime causes of neuroAIDS, which happens due to the ingress of HIV by direct permeation across the blood-brain barrier (BBB) or else via peripherally infected macrophage into the central nervous system (CNS). The BBB performs as a stringent barricade for the delivery of therapeutics drugs. The intranasal route of drug administration exhibits as a non-invasive technique to bypass the BBB for the delivery of antiretroviral drugs and other active pharmaceutical ingredients inside the brain and CNS. This method is fruitful for the drugs that are unable to invade the BBB to show its action in the CNS and thus erase the demand of systemic delivery and thereby shrink systemic side effects. Drug delivery from the nose to the brain/CNS takes very less time through both olfactory and trigeminal nerves. Intranasal delivery does not require the involvement of any receptor as it occurs by an extracellular route. Nose to brain delivery also involves nasal associated lymphatic tissues (NALT) and deep cervical lymph nodes. However, very little research has been done to explore the utility of nose to brain delivery of antiretroviral drugs in the treatment of neuroAIDS. This review focuses on the potential of nasal route for the effective delivery of antiretroviral nanoformulations directly from nose to the brain.

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.

Recent Advances in the Use of Focused Ultrasound for Magnetic Resonance Image-Guided Therapeutic Nanoparticle Delivery to the Central Nervous System

Targeting systemically-administered drugs and genes to specific regions of the central nervous system (CNS) remains a challenge. With applications extending into numerous disorders and cancers, there is an obvious need for approaches that facilitate the delivery of therapeutics across the impervious blood-brain barrier (BBB). Focused ultrasound (FUS) is an emerging treatment method that leverages acoustic energy to oscillate simultaneously administered contrast agent microbubbles. This FUS-mediated technique temporarily disrupts the BBB, allowing ordinarily impenetrable agents to diffuse and/or convect into the CNS. Under magnetic resonance image guidance, FUS and microbubbles enable regional targeting-limiting the large, and potentially toxic, dosage that is often characteristic of systemically-administered therapies. Subsequent to delivery across the BBB, therapeutics face yet another challenge: penetrating the electrostatically-charged, mesh-like brain parenchyma. Non-bioadhesive, encapsulated nanoparticles can help overcome this additional barrier to promote widespread treatment in selected target areas. Furthermore, nanoparticles offer significant advantages over conventional systemically-administered therapeutics. Surface modifications of nanoparticles can be engineered to enhance targeted cellular uptake, and nanoparticle formulations can be tailored to control many pharmacokinetic properties such as rate of drug liberation, distribution, and excretion. For instance, nanoparticles loaded with gene plasmids foster relatively stable transfection, thus obviating the need for multiple, successive treatments. As the formulations and applications of these nanoparticles can vary greatly, this review article provides an overview of FUS coupled with polymeric or lipid-based nanoparticles currently utilized for drug delivery, diagnosis, and assessment of function in the CNS.

Suitability of RPMI 2650 cell models for nasal drug permeability prediction

The RPMI 2650 cell line has been a subject of evaluation as a physiological and pharmacological model of the nasal epithelial barrier. However, its suitability for drug permeability assays has not yet been established on a sufficiently large set of model drugs. We investigated two RPMI 2650 cell models (air-liquid and liquid-liquid) for nasal drug permeability determination by adopting the most recent regulatory guidelines on showing suitability of in vitro permeability methods for drug permeability classification. The permeability of 23 model drugs and several zero permeability markers across the cell models was assessed. The functional expression of two efflux transporters P-glycoprotein (P-gp) and Breast Cancer Resistant Protein (BCRP) was shown to be negligible by bidirectional transport studies using appropriate transporter substrates and inhibitors. The model drug permeability determined in the two RPMI 2650 cell models was correlated with the fully differentiated nasal epithelial model (MucilAir™). Additionally, correlations between the drug permeability in the investigated cell models and the ones determined in the Caco-2 cells and isolated rat jejunum were established. In conclusion, the air-liquid RPMI 2650 cell model is a promising pharmacological model of the nasal epithelial barrier and is much more suitable than the liquid-liquid model for nasal drug permeability prediction.

Improved In Vitro Model for Intranasal Mucosal Drug Delivery: Primary Olfactory and Respiratory Epithelial Cells Compared with the Permanent Nasal Cell Line RPMI 2650

Background: The epithelial layer of the nasal mucosa is the first barrier for drug permeation during intranasal drug delivery. With increasing interest for intranasal pathways, adequate in vitro models are required. Here, porcine olfactory (OEPC) and respiratory (REPC) primary cells were characterised against the nasal tumour cell line RPMI 2650. Methods: Culture conditions for primary cells from porcine nasal mucosa were optimized and the cells characterised via light microscope, RT-PCR and immunofluorescence. Epithelial barrier function was analysed via transepithelial electrical resistance (TEER), and FITC-dextran was used as model substance for transepithelial permeation. Beating cilia necessary for mucociliary clearance were studied by immunoreactivity against acetylated tubulin. Results: OEPC and REPC barrier models differ in TEER, transepithelial permeation and MUC5AC levels. In contrast, RPMI 2650 displayed lower levels of MUC5AC, cilia markers and TEER, and higher FITC-dextran flux rates. Conclusion: To screen pharmaceutical formulations for intranasal delivery in vitro, translational mucosal models are needed. Here, a novel and comprehensive characterisation of OEPC and REPC against RPMI 2650 is presented. The established primary models display an appropriate model for nasal mucosa with secreted MUC5AC, beating cilia and a functional epithelial barrier, which is suitable for long-term evaluation of sustained release dosage forms.

Increased Nose-to-Brain Delivery of Melatonin Mediated by Polycaprolactone Nanoparticles for the Treatment of Glioblastoma

PURPOSE

Intranasal administration has been extensively applied to deliver drugs to the brain. In spite of its unfavorable biopharmaceutic properties, melatonin (MLT) has demonstrated anticancer effects against glioblastoma. This study describes the nose-to-brain delivery of MLT-loaded polycaprolactone nanoparticles (MLT-NP) for the treatment of glioblastoma.

METHODS

MLT-NP were prepared by nanoprecipitation. Following intranasal administration in rats, brain targeting of the formulation was demonstrated by fluorescence tomography. Brain and plasma pharmacokinetic profiles were analyzed. Cytotoxicity against U87MG glioblastoma cells and MRC-5 non-tumor cells was evaluated.

RESULTS

MLT-NP increased the drug apparent water solubility ~35 fold. The formulation demonstrated strong activity against U87MG cells, resulting in IC50 ~2500 fold lower than that of the free drug. No cytotoxic effect was observed against non-tumor cells. Fluorescence tomography images evidenced the direct translocation of nanoparticles from nasal cavity to the brain. Intranasal administration of MLT-NP resulted in higher AUC_brain and drug targeting index compared to the free drug by either intranasal or oral route.

CONCLUSIONS

Nanoencapsulation of MLT was crucial for the selective antitumoral activity against U87MG. In vivo evaluation confirmed nose-to-brain delivery of MLT mediated by nanoparticles, highlighting the formulation as a suitable approach to improve glioblastoma therapy.

IL-17c is involved in olfactory mucosa responses to Poly(I:C) mimicking virus presence

At the interface of the environment and the nervous system, the olfactory mucosa (OM) is a privileged pathway for environmental toxicants and pathogens towards the central nervous system. The OM is known to produce antimicrobial and immunological components but the mechanisms of action of the immune system on the OM remain poorly explored. IL-17c is a potent mediator of respiratory epithelial innate immune responses, whose receptors are highly expressed in the OM of mice. We first characterized the presence of the IL-17c and its receptors in the OM. While IL-17c was weakly expressed in the control condition, it was strongly expressed in vivo after intranasal administration of polyinosinic-polycytidylic (Poly I:C), a Toll Like Receptor 3 agonist, mimicking a viral infection. Using calcium imaging and electrophysiological recordings, we found that IL-17c can effectively activate OM cells through the release of ATP. In the longer term, intranasal chronic instillations of IL-17c increased the cellular dynamics of the epithelium and promoted immune cells infiltrations. Finally, IL-17c decreased cell death induced by Poly(I:C) in an OM primary culture. The OM is thus a tissue highly responsive to immune mediators, proving its central role as a barrier against airway pathogens.

Current approaches to enhancing oxime reactivator delivery into the brain

The misuse of organophosphate compounds still represents a current threat worldwide. Treatment of poisoning with organophosphates (OPs) remains unsatisfactorily resolved despite the extensive investment in research in academia. There are no universal, effective and centrally-active acetylcholinesterase (AChE) reactivators to countermeasure OP intoxication. One major obstacle is to overcome the blood-brain barrier (BBB). The central compartment is readily accessible by the OPs which are lipophilic bullets that can easily cross the BBB, whereas first-line therapeutics, namely oxime-based AChE reactivators and atropine, do not cross or do so rather slowly. The limitation of oxime-based AChE reactivators can be ascribed to their chemical nature, bearing a positive charge which is essential either for their AChE affinity or their reactivating potency. The aim of this article is to review the methods for targeting the brain by oxime reactivators that have been developed so far. Approaches using prodrugs, lipophilicity enhancement, or sugar-based oximes have been rather unsuccessful. However, other strategies have been more promising, such as the use of nanoparticles or co-administration of the reactivator with efflux transporter inhibitors. Encouraging results have also been associated with intranasal delivery, but research in this field is still at the beginning. Further research of auspicious approaches is inevitable.

Targeted drug delivery to the brain via intranasal nanoemulsion: Available proof of concept and existing challenges

Intranasal delivery has shown to circumvent blood-brain-barrier (BBB) and deliver the drugs into the CNS at a higher rate and extent than other conventional routes. The mechanism of drug transport from nose-to-brain is not fully understood yet, but several neuronal pathways are considered to be involved. Intranasal nanoemulsion for brain targeting is investigated extensively. Higher brain distribution of drug after administering intranasal nanoemulsion was established by many researchers. Issues with nasomucosal clearance are solved by formulating modified nanoemulsion; for instance, mucoadhesive nanoemulsion or in situ nanoemulgel. However, no intranasal nanoemulsion for brain targeted drug delivery has been able to cross the way from 'benches to bed-side' of patients. Possibilities of toxicity by repeated administration, irregular nasal absorption during the diseased condition, use of a high amount of surfactants are few of the persisting challenges that need to overcome in coming days. Understanding the ways how current developments has solved some challenges is necessary. At the same time, the future direction of the research on intranasal nanoemulsion should be figured out based on existing challenges. This review is focused on the current developments of intranasal nanoemulsion with special emphasis on the existing challenges that would help to set future research direction.

Acrylated Eudragit® E PO as a novel polymeric excipient with enhanced mucoadhesive properties for application in nasal drug delivery

Eudragit® E PO (EPO) is a terpolymer based on N,N-dimethylaminoethyl methacrylate with methylmethacrylate and butylmethacrylate, produced by Evonik Industries AG as a pharmaceutical excipient. In this work, EPO was chemically modified through reaction with acryloyl chloride. The successful modification of EPO was confirmed by FTIR, NMR-spectroscopy, elemental and thermal analysis. The degree of acrylation was determined by permanganatometric titration. The slug mucosal irritation test was used to demonstrate non-irritant nature of EPO and its acrylated derivatives (AEPO). The mucoadhesive properties of EPO and AEPO were evaluated using freshly excised sheep nasal mucosa and it was demonstrated that acrylated polymers facilitated greater retention of sodium fluorescein on mucosal surfaces compared to solution mixture of this dye solution with EPO as well as free dye.

Epilepsy Disease and Nose-to-Brain Delivery of Polymeric Nanoparticles: An Overview

Epilepsy is the fourth most common global neurological problem, which can be considered a spectrum disorder because of its various causes, seizure types, its ability to vary in severity and the impact from person to person, as well as its range of co-existing conditions. The approaches to drug therapy of epilepsy are directed at the control of symptoms by chronic administration of antiepileptic drugs (AEDs). These AEDs are administered orally or intravenously but alternative routes of administration are needed to overcome some important limits. Intranasal (IN) administration represents an attractive route because it is possible to reach the brain bypassing the blood brain barrier while the drug avoids first-pass metabolism. It is possible to obtain an increase in patient compliance for the easy and non-invasive route of administration. This route, however, has some drawbacks such as mucociliary clearance and the small volume that can be administered, in fact, only drugs that are efficacious at low doses can be considered. The drug also needs excellent aqueous solubility or must be able to be formulated using solubilizing agents. The use of nanomedicine formulations able to encapsulate active molecules represents a good strategy to overcome several limitations of this route and of conventional drugs. The aim of this review is to discuss the innovative application of nanomedicine for epilepsy treatment using nose-to-brain delivery with particular attention focused on polymeric nanoparticles to load drugs.

How to characterize a nasal product. The state of the art of in vitro and ex vivo specific methods

Nasal delivery offers many benefits over other conventional routes of delivery (e.g. oral or intravenous administration). Benefits include, among others, a fast onset of action, non-invasiveness and direct access to the central nervous system. The nasal cavity is not only limited to local application (e.g. rhinosinusitis) but can also provide direct access to other sites in the body (e.g. the central nervous system or systemic circulation). However, both the anatomy and the physiology of the nose impose their own limitations, such as a small volume for delivery or rapid mucociliary clearance. To meet nasal-specific criteria, the formulator has to complete a plethora of tests, in vitro and ex vivo, to assess the efficacy and tolerance of a new drug-delivery system. Moreover, depending on the desired therapeutic effect, the delivery of the drug should target a specific pathway that could potentially be achieved through a modified release of this drug. Therefore, this review focuses on specific techniques that should be performed when a nasal formulation is developed. The review covers both the tests recommended by regulatory agencies (e.g. the Food and Drug Administration) and other complementary experiments frequently performed in the field.

Intranasal Perillyl Alcohol for Glioma Therapy: Molecular Mechanisms and Clinical Development

Intracranial malignancies, such as primary brain cancers and brain-localized metastases derived from peripheral cancers, are particularly difficult to treat with therapeutic agents, because the blood-brain barrier (BBB) effectively minimizes brain entry of the vast majority of agents arriving from the systemic circulation. Intranasal administration of cancer drugs has the potential to reach the brain via direct nose-to-brain transport, thereby circumventing the obstacle posed by the BBB. However, in the field of cancer therapy, there is a paucity of studies reporting positive results with this type of approach. A remarkable exception is the natural compound perillyl alcohol (POH). Its potent anticancer activity was convincingly established in preclinical studies, but it nonetheless failed in subsequent clinical trials, where it was given orally and displayed hard-to-tolerate gastrointestinal side effects. Intriguingly, when switched to intranasal delivery, POH yielded highly promising activity in recurrent glioma patients and was well tolerated. As of 2018, POH is the only intranasally delivered compound in the field of cancer therapy (outside of cancer pain) that has advanced to active clinical trials. In the following, we will introduce this compound, summarize its molecular mechanisms of action, and present the latest data on its clinical evaluation as an intranasally administered agent for glioma.