Enhanced Stability and Solidification of Volatile Eugenol by Cyclodextrin-Metal Organic Framework for Nasal Powder Delivery.

Eugenol (Eug) holds potential as a treatment for bacterial rhinosinusitis by nasal powder drug delivery. To stabilization and solidification of volatile Eug, herein, nasal inhalable γ-cyclodextrin metal-organic framework (γ-CD-MOF) was investigated as a carrier by gas-solid adsorption method. The results showed that the particle size of Eug loaded by γ-CD-MOF (Eug@γ-CD-MOF) distributed in the range of 10-150 µm well. In comparison to γ-CD and ß-CD-MOF, γ-CD-MOF has higher thermal stability to Eug. And the intermolecular interactions between Eug and the carriers were verified by characterizations and molecular docking. Based on the bionic human nasal cavity model, Eug@γ-CD-MOF had a high deposition distribution (90.07 ± 1.58%). Compared with free Eug, the retention time Eug@γ-CD-MOF in the nasal cavity was prolonged from 5 min to 60 min. In addition, the cell viability showed that Eug@γ-CD-MOF (Eug content range 3.125-200 µg/mL) was non-cytotoxic. And the encapsulation of γ-CD-MOF could not reduce the bacteriostatic effect of Eug. Therefore, the biocompatible γ-CD-MOF could be a potential and valuable carrier for nasal drug delivery to realize solidification and nasal therapeutic effects of volatile oils.

The vomeronasal organ and incisive duct of harbor seals are modified to secrete acidic mucus into the nasal cavity.

Most terrestrial mammals have a vomeronasal system to detect specific chemicals. The peripheral organ of this system is a vomeronasal organ (VNO) opening to the incisive duct, and its primary integrative center is an accessory olfactory bulb (AOB). The VNO in seals is thought to be degenerated like whales and manatees, unlike otariids, because of the absence of the AOB. However, olfaction plays pivotal roles in seals, and thus we conducted a detailed morphological evaluation of the vomeronasal system of three harbor seals (Phoca vitulina). The VNO lumen was not found, and the incisive duct did not open into the oral cavity but was recognized as a fossa on the anteroventral side of the nasal cavity. This fossa is rich in mucous glands that secrete acidic mucopolysaccharides, which might originate from the vomeronasal glands. The olfactory bulb consisted only of a main olfactory bulb that received projections from the olfactory mucosa, but an AOB region was not evident. These findings clarified that harbor seals do not have a VNO to detect some chemicals, but the corresponding region is a specialized secretory organ.

Characterizing regional drug delivery within the nasal airways.

INTRODUCTION: The nose has been receiving increased attention as a route for drug delivery. As the site of deposition constitutes the first point of contact of the body with the drug, characterization of the regional deposition of intranasally delivered droplets or particles is paramount to formulation and device design of new products. AREAS COVERED: This review article summarizes the recent literature on intranasal regional drug deposition evaluated in vivo, in vitro and in silico, with the aim of correlating parameters measured in vitro with formulation and device performance. We also highlight the relevance of regional deposition to two emerging applications: nose-to-brain drug delivery and intranasal vaccines. EXPERT OPINION: As in vivo studies of deposition can be costly and time-consuming, researchers have often turned to predictive in vitro and in silico models. Variability in deposition is high due in part to individual differences in nasal geometry, and a complete predictive model of deposition based on spray characteristics remains elusive. Carefully selected or idealized geometries capturing population average deposition can be useful surrogates to in vivo measurements. Continued development of in vitro and in silico models may pave the way for development of less variable and more effective intranasal drug products.

The Effect of Surgical Procedure in the Nasal Cavity on the Passive Avoidance Conditioning and the Hypothalamic Level of Monoamines in Rats.

A rat biological model of septoplasty was used to study the effect of surgery on passive avoidance conditioning (PAC). Septoplasty was shown to increase anxiety and to reduce exploratory activity in rodents during PAC. A neurochemical analysis of the hypothalamus was carried out immediately after the end of the experiment and showed an increase in norepinephrine (NE) metabolism after septoplasty. The finding was tentatively associated with activation of the hypothalamic-pituitary-adrenal axis.

Swimming short fibrous nasal drops achieving intraventricular administration.

Adequate drug delivery across the blood-brain barrier (BBB) is a critical factor in treating central nervous system (CNS) disorders. Inspired by swimming fish and the microstructure of the nasal cavity, this study is the first to develop swimming short fibrous nasal drops that can directly target the nasal mucosa and swim in the nasal cavity, which can effectively deliver drugs to the brain. Briefly, swimming short fibrous nasal drops with charged controlled drug release were fabricated by electrospinning, homogenization, the π-π conjugation between indole group of fibers, the benzene ring of leucine-rich repeat kinase 2 (LRRK2) inhibitor along with charge-dipole interaction between positively charged poly-lysine (PLL) and negatively charged surface of fibers; this enabled these fibers to stick to nasal mucosa, prolonged the residence time on mucosa, and prevented rapid mucociliary clearance. In vitro, swimming short fibrous nasal drops were biocompatible and inhibited microglial activation by releasing an LRRK2 inhibitor. In vivo, luciferase-labelled swimming short fibrous nasal drops delivered an LRRK2 inhibitor to the brain through the nasal mucosa, alleviating cognitive dysfunction caused by sepsis-associated encephalopathy by inhibiting microglial inflammation and improving synaptic plasticity. Thus, swimming short fibrous nasal drops is a promising strategy for the treatment of CNS diseases.

Molecular Evidence for Olfactory Neuroblastoma as a Tumor of Malignant Globose Basal Cells.

Olfactory neuroblastoma (ONB, esthesioneuroblastoma) is a sinonasal cancer with an underdeveloped diagnostic toolkit, and is the subject of many incidents of tumor misclassification throughout the literature. Despite its name, connections between the cancer and normal cells of the olfactory epithelium have not been systematically explored and markers of olfactory epithelial cell types are not deployed in clinical practice. Here, we utilize an integrated human-mouse single-cell atlas of the nasal mucosa, including the olfactory epithelium, to identify transcriptomic programs that link ONB to a specific population of stem/progenitor cells known as olfactory epithelial globose basal cells (GBCs). Expression of a GBC transcription factor NEUROD1 distinguishes both low- and high-grade ONB from sinonasal undifferentiated carcinoma, a potential histologic mimic with a distinctly unfavorable prognosis. Furthermore, we identify a reproducible subpopulation of highly proliferative ONB cells expressing the GBC stemness marker EZH2, suggesting that EZH2 inhibition may play a role in the targeted treatment of ONB. Finally, we study the cellular states comprising ONB parenchyma using single-cell transcriptomics and identify evidence of a conserved GBC transcriptional regulatory circuit that governs divergent neuronal-versus-sustentacular differentiation. These results link ONB to a specific cell type for the first time and identify conserved developmental pathways within ONB that inform diagnostic, prognostic, and mechanistic investigation.

18F-fluorodeoxyglucose positron emission tomography findings of peripheral nerve sheath tumour of the nasal cavity in a dog.

An 8-year-old Miniature Poodle presented with chronic sneezing and unilateral epistaxis. A left-sided intranasal mass was identified on computed tomography. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed to evaluate the metabolic activity of the mass. The intranasal mass showed mildly increased 18F-FDG uptake. The maximal and mean standardized uptake values (SUVs) of the mass were 3.4 and 2.6, respectively. The maximal SUV of the mass/mean SUV of the normal liver was 2.5. The 7-cm soft, pink mass was easily removed through rhinoscopy, with subsequent dramatic improvement in clinical signs. Histopathological and immunohistochemical analyses determined that the mass was an intermediate-grade malignant peripheral nerve sheath tumour (PNST). This is the first report of 18F-FDG PET findings in a PNST in dogs.

Prognostic significance of PD-1, CTLA-4, CD4, and CD8 expression in olfactory neuroblastoma.

There are limited data regarding immune surveillance mechanisms in olfactory neuroblastoma. We investigated the expression of programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), CD4, and CD8 in olfactory neuroblastoma to identify potential therapeutic targets. Immunohistochemistry was used to detect PD-1 and CTLA-4 and measure the numbers of CD4+ and CD8+ T cells in 56 patients with olfactory neuroblastoma. The relationships between these molecules in tumor microenvironment, clinicopathological features, and survival were analyzed. The prevalence of PD-1 in Kadish C stage was 24.14%, significantly greater than in Kadish A and B stage. CD4+ T-cell and CD8+ T-cell levels correlated with higher Hyams histological grade and Kadish stage. In addition, PD-1 was related positively with CTLA-4, CD4+ T cells, and CD8+ T cells in olfactory neuroblastoma. Univariate survival analysis showed that higher PD-1 positivity, CD8+ T cells, and Hyams grade correlated with worse clinical outcome. Multivariate analysis showed that the expression of PD-1 was an independent parameter for poor prognosis. In conclusion, olfactory neuroblastoma with PD-1 expression had more aggressive clinicopathological features and worse prognosis. PD-1 may potentially predict the outcome of olfactory neuroblastoma patients.

The prognostic value of S-100 protein and Ki-67 index in olfactory neuroblastoma.

OBJECTIVE: To evaluate the prognostic value of S-100 protein and Ki-67 labeling index in olfactory neuroblastomas. METHODS: A retrospective study was conducted on a cohort of 85 patients with olfactory neuroblastomas. The immunohistochemical expression of S-100 and Ki-67 was assessed, and the predictive value of S-100 and Ki-67 was further evaluated. The optimal cutoff value of Ki-67 labeling index was determined using time-dependent receiver operating characteristic curve analysis. Overall survival and progression-free survival were assessed using the Kaplan-Meier method. RESULTS: A cut-off Ki-67 labeling index value of 67.5% was determined for prognosis in patients with olfactory neuroblastomas. There was a significant correlation between Ki-67 expression and cervical lymph node metastasis (P = 0.049). Compared with S-100 (+), S-100 (-) was associated with a higher rate of lymph node metastasis and a higher level of Ki-67 (P = 0.007, < 0.001, respectively), as well as an advanced Kadish stage (P = 0.037). Survival analyses showed that patients with S-100 (+) had better 5-year overall survival than those with S-100 (-) (P = 0.028), and patients with both S-100 (+) and Ki-67 (<67.5%) had superior 5-year overall survival compared with all the other patients (P = 0.0225). CONCLUSION: Our findings suggest that S-100 combined with Ki-67 labeling index are reliable prognostic factors in patients with olfactory neuroblastomas.

[IgG4-related disease in nasal cavity and paranasal sinuses: a clinicopathological analysis of ten cases].

Objective: To study clinicopathological features and differential diagnosis of IgG4-related diseases (IgG4-RD) in nasal cavity and paranasal sinuses. Methods: A retrospective analysis was performed in patients presenting initially with rhinosinusitis or a nasal mass, who also underwent nasal mucosa biopsy in Beijing Tongren Hospital Affiliated to Capital Medical University, from March 2016 to March 2021. According to the latest international classification diagnostic criteria of IgG4-RD published by the American Society of Rheumatology (ACR)/European Association for Rheumatology (EULAR) in 2019, 10 cases of nasal cavity and paranasal sinuses IgG4-RD were diagnosed and included in the study. The clinical features, histopathology and immunohistochemical expression of IgG and IgG4 were analyzed. Results: Among the 10 patients, five patients were male and five female. The age ranged from 30 to 71 years (median 52.7 years). Nasal polyp/nasal masses were seen in six cases, and lacrimal gland swelling was found in four cases. The serum IgG and IgG4 level was increased in four cases. Microscopically, all 10 cases showed intense lymphoplasmocytic infiltration and varying degrees of fibrosis in nasal or sinus mucosa, while four cases showed occlusive vasculitis. The number of IgG4 positive plasma cells in nasal mucosa was more than 10/high power field (HPF), with a mean of 67/HPF. The number of IgG4 positive plasma cells in the cases with severe fibrosis was significantly lower than in those without. The ratio of IgG4+/IgG+plasma cells was higher than 40% in six cases. Conclusions: IgG4-RD in nasal cavity and paranasal sinuses is a local manifestation of a systemic disease, while nasal cavity and paranasal sinuses are rarely involved by IgG4-RD. The diagnosis is based on clinical symptoms, imaging, IgG4-related serology and histopathologic scores. Histopathology has a core diagnostic value. IgG4 serology and imaging have important diagnostic values in the cases without biopsy.

Enhanced presence of serotonin in nasal cavity after autologous stimulation.

OBJECTIVE: Serotonin, which is a vasoactive amine, is an important neurotransmitter and is involved in many behavioral and psychological phenomena, such as pain, appetite, mood, and sleep. The primary purpose of our study was to investigate the effect of high-pressure administration of sterile physiological saline isotonic solution (HpPSIS) into nasal cavity and to determine the expression of the serotonin. PATIENTS AND METHODS: The study was made in two branches, the previous with 14 volunteers, the subsequent study with 40 patients with mild anxiety disorder. The middle third of the inferior turbinate epithelial cells on the right nostril was scraped using a sterile curette and indicated as (pre), then, a spray of sterilized isotonic solution at high pressure on the left nostril was delivered, and 5 minutes later a similar stimulation was delivered on the same nostril. The stimulation was made with a specific spray dispenser. The middle third of the inferior turbinate epithelial cells on the left nostril was scraped using a sterile curette and indicated as (post). Then, based on the first part of our study, we started the second part and gave a treatment on forty new patients with anxiety disorder. RESULTS: The results of these studies highlight the possibility of endogenous enhancement of serotonin by stimulation of mast cells. In the first part of the study, Serotonin significantly increased in protein extracts after treatment (64.35±5.33 vs. 10.97±2.17; unpaired two tailed t-test, t=9.8, df=24, p≤0.0001; F=6.035; DFn=12; DFd=12). In the second part of the study, in patients treated with HpPSIS, we observed improvement of mood, after one, two and three months, with a statistically significant reduction of DASS-21, while no reduction was observed in control patients, treated with normal pressure commercial spray. CONCLUSIONS: This pilot study showed that the topical treatment of HpPHIS increases serotonin levels in nasal cavity. The observation reported in this study opens the way to a new valid strategy to enhance the level of endogenous serotonin. We observed a significant improvement of ASI on patients during HpPHIS therapy.

Prognostic value of microvessel density and its correlation with clinicopathological features in human olfactory neuroblastoma.

Although angiogenesis plays an important role in tumor growth and invasion, its role in the progression of olfactory neuroblastoma (ONB) has rarely been published. The aim of the present research was to analyze the prognostic role of microvessel density (MVD) in ONB and its association with clinicopathological parameters. 70 ONB cases were assessed for immunohistochemical expression of CD31, CD34, CD105, VEGF, and VEGFR2. The expression of CD105-MVD was negatively associated with histological grade and tumor Kadish stage, and its expression was positively correlated with the expression of VEGF/VEGFR2. Low expression of CD105-MVD and high tumor histological grade were strongly associated with poor survival. Thus, CD105-MVD was demonstrated to be a valuable independent prognostic indicator for ONB. MVD is expected to be useful as an important marker to distinguish tumor histological grade.

Clinical outcomes, Kadish-INSICA staging and therapeutic targeting of somatostatin receptor 2 in olfactory neuroblastoma.

INTRODUCTION: Olfactory neuroblastoma (ONB) is a rare cancer of the sinonasal region. We provide a comprehensive analysis of this malignancy with molecular and clinical trial data on a subset of our cohort to report on the potential efficacy of somatostatin receptor 2 (SSTR2)-targeting imaging and therapy. METHODS: We conducted a retrospective analysis of 404 primary, locally recurrent, and metastatic olfactory neuroblastoma (ONB) patients from 12 institutions in the United States of America, United Kingdom and Europe. Clinicopathological characteristics and treatment approach were evaluated. SSTR2 expression, SSTR2-targeted imaging and the efficacy of peptide receptor radionuclide therapy [PRRT](177Lu-DOTATATE) were reported in a subset of our cohort (LUTHREE trial; NCT03454763). RESULTS: Dural infiltration at presentation was a significant predictor of overall survival (OS) and disease-free survival (DFS) in primary cases (n = 278). Kadish-Morita staging and Dulguerov T-stage both had limitations regarding their prognostic value. Multivariable survival analysis demonstrated improved outcomes with lower stage and receipt of adjuvant radiotherapy. Prophylactic neck irradiation significantly reduces the rate of nodal recurrence. 82.4% of the cohort were positive for SSTR2; treatment of three metastatic cases with SSTR2-targeted peptide-radionuclide receptor therapy (PRRT) in the LUTHREE trial was well-tolerated and resulted in stable disease (SD). CONCLUSIONS: This study presents pertinent clinical data from the largest dataset, to date, on ONB. We identify key prognostic markers and integrate these into an updated staging system, highlight the importance of adjuvant radiotherapy across all disease stages, the utility of prophylactic neck irradiation and the potential efficacy of targeting SSTR2 to manage disease.

Transplantation of Human Induced Pluripotent Stem Cell-Derived Airway Cells on Vitrigel Membrane into Rat Nasal Cavity.

The nasal mucosa functions as a frontline biological defense against various foreign substances and pathogens. Maintaining homeostasis of the nasal epithelium is necessary to promote good health. Nasal epithelia are constantly replaced under normal conditions. However, hereditary diseases, including primary ciliary dyskinesia and cystic fibrosis, can result in intractable dysfunction of the nasal mucosa. Since there is no treatment for this underlying condition, extrinsic manipulation is necessary to recover and maintain nasal epithelia in cases of hereditary diseases. In this study, we explored the use of airway epithelial cells (AECs), including multiciliated airway cells, derived from human induced pluripotent stem cells (iPSCs) on porcine atelocollagen vitrigel membranes, as a candidate of a therapeutic method for irreversible nasal epithelial disorders. To confirm the regenerative capacity of iPSC-derived AECs, we transplanted them into nasal cavities of nude rats. Although the transplanted cells were found within cysts isolated from the recipient nasal respiratory epithelia, they survived in some rats. Furthermore, the surviving cells were composed of multiple cell types similar to the human airway epithelia. The results could contribute to the development of novel transplantation-related technologies for the treatment of severe irreversible nasal epithelial disorders. Impact Statement Nasal respiratory epithelia are important for the functions of nasal cavity, including humidifying the air and filtering various toxic substances. However, hereditary diseases, including primary ciliary dyskinesia and cystic fibrosis, can result in intractable dysfunction of the nasal mucosa. Our novel method to transplant airway epithelial cells derived from human induced pluripotent stem cells will be a candidate method to replace malfunctioned nasal respiratory epithelia in such a situation. To secure our method's safety, we used porcine atelocollagen vitrigel membranes, which prevent the immune response and bovine spongiform encephalopathy, as a scaffold.

A systems genomics approach uncovers molecular associates of RSV severity.

Respiratory syncytial virus (RSV) infection results in millions of hospitalizations and thousands of deaths each year. Variations in the adaptive and innate immune response appear to be associated with RSV severity. To investigate the host response to RSV infection in infants, we performed a systems-level study of RSV pathophysiology, incorporating high-throughput measurements of the peripheral innate and adaptive immune systems and the airway epithelium and microbiota. We implemented a novel multi-omic data integration method based on multilayered principal component analysis, penalized regression, and feature weight back-propagation, which enabled us to identify cellular pathways associated with RSV severity. In both airway and immune cells, we found an association between RSV severity and activation of pathways controlling Th17 and acute phase response signaling, as well as inhibition of B cell receptor signaling. Dysregulation of both the humoral and mucosal response to RSV may play a critical role in determining illness severity.

Determinants of SARS-CoV-2 entry and replication in airway mucosal tissue and susceptibility in smokers.

Understanding viral tropism is an essential step toward reducing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, decreasing mortality from coronavirus disease 2019 (COVID-19) and limiting opportunities for mutant strains to arise. Currently, little is known about the extent to which distinct tissue sites in the human head and neck region and proximal respiratory tract selectively permit SARS-CoV-2 infection and replication. In this translational study, we discover key variabilities in expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), essential SARS-CoV-2 entry factors, among the mucosal tissues of the human proximal airways. We show that SARS-CoV-2 infection is present in all examined head and neck tissues, with a notable tropism for the nasal cavity and tracheal mucosa. Finally, we uncover an association between smoking and higher SARS-CoV-2 viral infection in the human proximal airway, which may explain the increased susceptibility of smokers to developing severe COVID-19. This is at least partially explained by differences in interferon (IFN)-ß1 levels between smokers and non-smokers.

Metabolic Reprogramming of Nasal Airway Epithelial Cells Following Infant Respiratory Syncytial Virus Infection.

Respiratory syncytial virus (RSV) is a seasonal mucosal pathogen that infects the ciliated respiratory epithelium and results in the most severe morbidity in the first six months of life. RSV is a common cause of acute respiratory infection during infancy and is an important early-life risk factor strongly associated with asthma development. While this association has been repeatedly demonstrated, limited progress has been made on the mechanistic understanding in humans of the contribution of infant RSV infection to airway epithelial dysfunction. An active infection of epithelial cells with RSV in vitro results in heightened central metabolism and overall hypermetabolic state; however, little is known about whether natural infection with RSV in vivo results in lasting metabolic reprogramming of the airway epithelium in infancy. To address this gap, we performed functional metabolomics, 13C glucose metabolic flux analysis, and RNA-seq gene expression analysis of nasal airway epithelial cells (NAECs) sampled from infants between 2-3 years of age, with RSV infection or not during the first year of life. We found that RSV infection in infancy was associated with lasting epithelial metabolic reprogramming, which was characterized by (1) significant increase in glucose uptake and differential utilization of glucose by epithelium; (2) altered preferences for metabolism of several carbon and energy sources; and (3) significant sexual dimorphism in metabolic parameters, with RSV-induced metabolic changes most pronounced in male epithelium. In summary, our study supports the proposed phenomenon of metabolic reprogramming of epithelial cells associated with RSV infection in infancy and opens exciting new venues for pursuing mechanisms of RSV-induced epithelial barrier dysfunction in early life.

New insights into structure and function of bis-phosphinic acid derivatives and implications for CFTR modulation.

C407 is a compound that corrects the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein carrying the p.Phe508del (F508del) mutation. We investigated the corrector effect of c407 and its derivatives on F508del-CFTR protein. Molecular docking and dynamics simulations combined with site-directed mutagenesis suggested that c407 stabilizes the F508del-Nucleotide Binding Domain 1 (NBD1) during the co-translational folding process by occupying the position of the p.Phe1068 side chain located at the fourth intracellular loop (ICL4). After CFTR domains assembly, c407 occupies the position of the missing p.Phe508 side chain. C407 alone or in combination with the F508del-CFTR corrector VX-809, increased CFTR activity in cell lines but not in primary respiratory cells carrying the F508del mutation. A structure-based approach resulted in the synthesis of an extended c407 analog G1, designed to improve the interaction with ICL4. G1 significantly increased CFTR activity and response to VX-809 in primary nasal cells of F508del homozygous patients. Our data demonstrate that in-silico optimized c407 derivative G1 acts by a mechanism different from the reference VX-809 corrector and provide insights into its possible molecular mode of action. These results pave the way for novel strategies aiming to optimize the flawed ICL4-NBD1 interface.

Morphology of GNAT3-immunoreactive chemosensory cells in the nasal cavity and pharynx of the rat.

Solitary chemosensory cells and chemosensory cell clusters are distributed in the pharynx and larynx. In the present study, the morphology and reflexogenic function of solitary chemosensory cells and chemosensory cell clusters in the nasal cavity and pharynx were examined using immunofluorescence for GNAT3 and electrophysiology. In the nasal cavity, GNAT3-immunoreactive solitary chemosensory cells were widely distributed in the nasal mucosa, particularly in the cranial region near the nostrils. Solitary chemosensory cells were also observed in the nasopharynx. Solitary chemosensory cells in the nasopharyngeal cavity were barrel like or slender in shape with long lateral processes within the epithelial layer to attach surrounding ciliated epithelial cells. Chemosensory cell clusters containing GNAT3-immunoreactive cells were also detected in the pharynx. GNAT3-immunoreactive cells gathered with SNAP25-immunoreactive cells in chemosensory clusters. GNAT3-immunoreactive chemosensory cells were in close contact with a few SP- or CGRP-immunoreactive nerve endings. In the pharynx, GNAT3-immunoreactive chemosensory cells were also attached to P2X3-immunoreactive nerve endings. Physiologically, the perfusion of 10 mM quinine hydrochloride (QHCl) solution induced ventilatory depression. The QHCl-induced reflex was diminished by bilateral section of the glossopharyngeal nerve, suggesting autonomic reflex were evoked by chemosensory cells in pharynx but not in nasal mucosa. The present results indicate that complex shape of nasopharyngeal solitary chemosensory cells may contribute to intercellular communication, and pharyngeal chemosensory cells may play a role in respiratory depression.

Overcoming the challenges of developing an intranasal diazepam rescue therapy for the treatment of seizure clusters.

Seizure clusters must be treated quickly and effectively to prevent progression to prolonged seizures and status epilepticus. Rescue therapy for seizure clusters has focused on the use of benzodiazepines. Although intravenous benzodiazepine administration is the primary route in hospitals and emergency departments, seizure clusters typically occur in out-of-hospital settings, where a more portable product that can be easily administered by nonmedical caregivers is needed. Thus, other methods of administration have been examined, including rectal, intranasal, intramuscular, and buccal routes. Following US Food and Drug Administration (FDA) approval in 1997, rectal diazepam became the mainstay of out-of-hospital treatment for seizure clusters in the United States. However, social acceptability and consistent bioavailability present limitations. Intranasal formulations have potential advantages for rescue therapies, including ease of administration and faster onset of action. A midazolam nasal spray was approved by the FDA in 2019 for patients aged 12 years or older. In early 2020, the FDA approved a diazepam nasal spray for patients aged 6 years or older, which has a different formulation than the midazolam nasal product and enhances aspects of bioavailability. Benzodiazepines, including diazepam, present significant challenges in developing a suitable intranasal formulation. Diazepam nasal spray contains dodecyl maltoside (DDM) as an absorption enhancer and vitamin E to increase solubility in an easy-to-use portable device. In a Phase 1 study, absolute bioavailability of the diazepam nasal spray was 97% compared with intravenous diazepam. Subsequently, the nasal spray demonstrated less variability in bioavailability than rectal gel (percentage of geometric coefficient of variation of area under the curve = 42%-66% for diazepam nasal spray compared with 87%-172% for rectal gel). The diazepam nasal spray safety profile is consistent with that expected for rectal diazepam, with low rates of nasal discomfort (≤6%). To further improve the efficacy of rescue therapy, investigation of novel intranasal benzodiazepine formulations is underway.