Intranasal sodium citrate solution improves olfaction in post-viral hyposmia

Spectrofluorometric determination of calcium in the human nasal secretions investigating the association with olfactory function

Ionic microenvironment of the nasal secretions especially calcium ions play essential role in the olfactory transmission. However, there is a critical need to determine the free calcium levels in healthy people's nasal secretions in contrast to those of patients with olfactory impairment. A selective spectrofluorometric method was created to quantify nasal calcium levels utilizing its quenching ability to the fluorescence of the functionalized carbon quantum dots. The surface of carbon quantum dots was functionalized with calcium ionophore A23187 and ion association complex, calcium phosphotungstate, to improve the selectively to quantify calcium ions. The functionalized carbon quantum dots exhibited a concentration-dependent fluorescence quenching upon interaction with calcium ions. Different factors influencing the quenching process were done to provide efficient analytical process. The new method, demonstrated accurate calcium determination over the concentration range of 200-4000 ng/mL. The suggested technique was used to measure the calcium in the nasal secretions of both healthy people and patients with olfactory impairment. The findings revealed significantly higher calcium levels in the patient with olfactory dysfunction (healthy vs. patient; 735 ± 20 ng/mL vs. 2987 ± 37 ng/mL, p < 0.05).

The Efficacy of Sodium Phytate as a Natural Chelating Agent in Reducing Elevated Calcium Levels in Nasal Mucus Among Individuals Experiencing Olfactory Dysfunction Following COVID-19: A Prospective Randomized Double-Controlled Clinical Trial

BACKGROUND

COVID-19 has been associated with olfactory disturbances in many infected patients. The increase in calcium levels in nasal secretions plays an essential role in the olfactory process with a desensitizing effect on olfactory receptor neurons and negative effects on odor transmission. Calcium chelating agents have the ability to bind calcium in nasal mucus and prevent the negative effects associated with calcium increase.

OBJECTIVES

The aim of this work is to demonstrate the intra-nasal topical application of sodium phytate, an environmentally friendly, non-harmful calcium chelating agent, to reduce the adverse effects of calcium on olfactory function and improve olfactory dysfunction according to COVID-19.

METHODS

Fifty-two patients with a previous COVID-19 and olfactory dysfunction lasting longer than 90 days were enrolled in a prospective, randomized, blinded, controlled clinical trial. Patients were divided into two equal groups: 26 patients received nasal spray containing 0.9% sodium chloride and 26 patients received nasal spray containing 1% sodium phytate. Olfactory function was measured before treatment and 1 month later using the Sniffin' Sticks test. Calcium content of nasal secretions was determined before and after treatment with an ion-selective electrode.

RESULTS

A significant improvement from anosmia to hyposmia was demonstrated after the use of sodium phytate compared with no improvement after the use of sodium chloride. In addition, a decrease in the level of calcium in nasal secretions was observed after the use of sodium phytate.

CONCLUSION

Sodium phytate has benefit role on improving the olfactory function after COVID-19.

Intra Nasal Use of Ethylene Diamine Tetra Acetic Acid for Improving Olfactory Dysfunction Post COVID-19

BACKGROUND

COVID-19 has been associated with olfactory dysfunction in many infected patients. The rise of calcium levels in the nasal secretions plays an essential role in the olfaction process with a desensitization effect on the olfactory receptor neurons and a negative impact on the olfaction transmission. Ethylene diamine tetra acetic acid (EDTA) is a chelating agent that can bind free calcium in the nasal secretions, thereby reducing the adverse effects of calcium on olfactory function.

OBJECTIVES

The objective of this work is to demonstrate the effect of intranasal EDTA on improving olfactory dysfunction following COVID-19.

METHODS

Fifty patients with a history of COVID-19 and olfactory dysfunction that persisted for more than 6 months were enrolled in the current prospective randomized clinical trial. Participants were randomized into 2 equal groups. Twenty-five patients were treated with olfactory training only, while the remaining 25 patients received treatment with olfactory training and a topical nasal spray of ethylene diamine tetra acetic acid. The olfactory function was assessed before treatment and 3 months later using the Sniffin' Sticks test. Additionally, the determination of calcium level in the nasal secretions was performed using an ion-selective electrode before treatment and 3 months later.

RESULTS

Eighty-eight percent of the patients treated with olfactory training in addition to EDTA exhibited clinical improvement, while 60% showed improvement in patients treated with olfactory training only. Furthermore, a significant decrease in the measured calcium level in the nasal secretions was demonstrated after the use of ethylene diamine tetra compared to patients treated with olfactory training only.

CONCLUSION

Ethylene diamine tetra acetic acid may be associated with an improvement of the olfactory function post-COVID-19.

Distinct smell and taste disorder phenotype of post-acute COVID-19 sequelae

PURPOSE

Olfactory dysfunction (OD) commonly accompanies coronavirus disease 2019 (COVID-19). We investigated the kinetics of OD resolution following SARS-CoV-2 infection (wild-type and alpha variant) and its impact on quality of life, physical and mental health.

METHODS

OD prevalence was assessed in an ambulatory COVID-19 survey (n = 906, ≥ 90 days follow-up) and an observational cohort of ambulatory and hospitalized individuals (n = 108, 360 days follow-up). Co-occurrence of OD with other symptoms and effects on quality of life, physical and mental health were analyzed by multi-dimensional scaling, association rule mining and semi-supervised clustering.

RESULTS

Both in the ambulatory COVID-19 survey study (72%) and the observational ambulatory and hospitalized cohort (41%) self-reported OD was frequent during acute COVID-19. Recovery from self-reported OD was slow (survey: median 28 days, observational cohort: 90 days). By clustering of the survey data, we identified a predominantly young, female, comorbidity-free group of convalescents with persistent OD and taste disorders (median recovery: 90 days) but low frequency of post-acute fatigue, respiratory or neurocognitive symptoms. This smell and taste disorder cluster was characterized by a high rating of physical performance, mental health, and quality of life as compared with convalescents affected by prolonged fatigue or neurocognitive complaints.

CONCLUSION

Our results underline the heterogeneity of post-acute COVID-19 sequelae calling for tailored management strategies. The persistent smell and taste disorder phenotype is characterized by good clinical, physical, and mental recovery and may pose a minor challenge for public health.

STUDY REGISTRATION

ClinicalTrials.gov: NCT04661462 (survey study), NCT04416100 (observational cohort).

Assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms

Purpose of review

To provide a detailed overview of the assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms.

Recent findings

COVID-19-related olfactory dysfunction can have a detrimental impact to the quality of life of patients. Prior to the COVID-19 pandemic, olfactory and taste disorders were a common but under-rated, under-researched and under-treated sensory loss. The pandemic has exacerbated the current unmet need for accessing good healthcare for patients living with olfactory disorders and other symptoms secondary to COVID-19. This review thus explores the associations that COVID-19 has with psychological, neuropsychiatric, and cognitive symptoms, and provide a framework and rationale for the assessment of patients presenting with COVID-19 olfactory dysfunction.

Summary

Acute COVID-19 infection and long COVID is not solely a disease of the respiratory and vascular systems. These two conditions have strong associations with psychological, neuropsychiatric, and cognitive symptoms. A systematic approach with history taking and examination particularly with nasal endoscopy can determine the impact that this has on the patient. Specific olfactory disorder questionnaires can demonstrate the impact on quality of life, while psychophysical testing can objectively assess and monitor olfaction over time. The role of cross-sectional imaging is not yet described for COVID-19-related olfactory dysfunction. Management options are limited to conservative adjunctive measures, with some medical therapies described.

Olfactory Function and Olfactory Disorders

The sense of smell is important. This became especially clear to patients with infection-related olfactory loss during the SARS-CoV-2 pandemic. We react, for example, to the body odors of other humans. The sense of smell warns us of danger, and it allows us to perceive flavors when eating and drinking. In essence, this means quality of life. Therefore, anosmia must be taken seriously. Although olfactory receptor neurons are characterized by regenerative capacity, anosmia is relatively common with about 5 % of anosmic people in the general population. Olfactory disorders are classified according to their causes (e. g., infections of the upper respiratory tract, traumatic brain injury, chronic rhinosinusitis, age) with the resulting different therapeutic options and prognoses. Thorough history taking is therefore important. A wide variety of tools are available for diagnosis, ranging from short screening tests and detailed multidimensional test procedures to electrophysiological and imaging methods. Thus, quantitative olfactory disorders are easily assessable and traceable. For qualitative olfactory disorders such as parosmia, however, no objectifying diagnostic procedures are currently available. Therapeutic options for olfactory disorders are limited. Nevertheless, there are effective options consisting of olfactory training as well as various additive drug therapies. The consultation and the competent discussion with the patients are of major importance.

Drug delivery to the brain via the nasal route of administration: exploration of key targets and major consideration factors

Background

Cranial nerve-related diseases such as brain tumors, Alzheimer's disease, and epilepsy are serious diseases that continue to threaten human. Brain-related diseases are increasing worldwide, including in the United States and Korea, and these increases are closely related to the exposure to harmful substances and excessive stress caused by rapid industrialization and environmental pollution. Drug delivery to the brain is very important for the effective prevention and treatment of brain-related diseases. However, due to the presence of the blood-brain barrier and the extensive first-pass metabolism effect, the general routes of administration such as oral and intravenous routes have limitations in drug delivery to the brain. Therefore, as an alternative, the nasal-brain drug delivery route is attracting attention as a route for effective drug delivery to the brain.

Areas covered

This review includes physiological factors, advantages, limitations, current application status, especially in clinical applications, and the necessary factors for consideration in formulation development related to nasal-brain drug delivery.

Expert opinion

The nasal-brain drug delivery route has the advantage of enhancing drug delivery to the brain locally, mainly through the olfactory route rather than the systemic circulation. The nasal-brain lymphatic system has recently attracted attention, and it has been implied that the delivery of anticancer drugs to the brain nervous system is possible effectively. However, there are limitations such as low drug permeability, as well as nasal mucosa and the mucociliary system, as obstacles in nasal-brain drug delivery. Therefore, to overcome the limitations of nasal-brain drug delivery, the use of nanocarriers and mucoadhesive agents is being attempted. However, very few drugs have been officially approved for clinical application via the nasal-brain drug delivery route. This is probably because the understanding of and related studies on nasal-brain drug delivery are limited. In this review, we tried to explore the major considerations and target factors in drug delivery through the nasal-brain route based on physiological knowledge and formulation research information. This will help to provide a mechanistic understanding of drug delivery through the nasal-brain route and bring us one step closer to developing effective formulations and drugs in consideration of the key factors for nasal-brain drug delivery.

Insight into the mechanisms of olfactory dysfunction by COVID-19

One of the unique symptoms of COVID-19 is chemosensory dysfunction. Almost three years since the beginning of the pandemic of COVID-19, there have been many studies on the symptoms, progress, and possible causes, and also studies on methods that may facilitate recovery of the senses. Studies have shown that some people recover their senses even within a couple of weeks whereas there are other patients that fail to recover chemosensory functions fully for several months and some never fully recover. Here we summarize the symptoms and the progress, and then review the papers on the causation as well as the treatments that may help facilitate the recovery of the symptoms. Depending on the differences in the levels of severity and the locations where the main pathological venues are, what is most effective in facilitating recovery can vary largely across patients and thus may require individualized strategies for each patient. The goal of this paper is to provide some thoughts on these choices depending on the differences in the causes and severity.

Management of Post-Infectious Anosmia and Hyposmia: A Systematic Review

BACKGROUND

Anosmia and hyposmia significantly affect patients' quality of life and have many etiologies, including trauma, inflammatory conditions including chronic rhinosinusitis, neoplasm, and viral infections, such as rhinovirus and SARS-CoV-2.

OBJECTIVE

Our purpose was to establish whether a consensus exists regarding optimal management of olfactory dysfunction and to provide insight into the treatment of anosmia in the current climate of increased prevalence secondary to COVID-19. Thus, we aimed to systematically review the literature on the management of non-Chronic-rhinosinusitis- related anosmia/hyposmia.

METHODS

PubMed, EMBASE, and Cochrane databases were searched for articles published since January 1990 using terms combined with Medical Subject Headings (MeSH). We included articles evaluating management of anosmia and hyposmia written in the English language, with original data, a minimum of 3 months of follow-up except for COVID-related studies, at least 2 patients, and well-defined and measurable outcomes.

RESULTS

A total of 3013 unique titles were returned upon the initial search. Of these, 297 abstracts were examined, yielding 19 full texts meeting inclusion criteria (8 with level 1 evidence, 3 with level 2, 1 with level 3, and 7 with level 4). The studies included a total of 1522 subjects, with follow up ranging from 3 to 72 months, with an exception for COVID related studies. Endpoints were based on clinically significant improvements of olfactory functions as measured through validated smell tests. Treatments with the most robust data were intranasal corticosteroids and olfactory training.

CONCLUSION

The literature on the treatment of anosmia and hyposmia includes randomized trials showing the efficacy of a few modalities. While further research is needed to expand therapeutic options for this debilitating condition, the current literature supports the use of olfactory training and topical corticosteroids.

Effect of Sodium Gluconate on Decreasing Elevated Nasal Calcium and Improving Olfactory Function Post COVID-19 Infection

Background

COVID-19 has been associated with temporary olfactory dysfunction in many infected patients. Calcium plays a great role in the olfaction process with negative feedback for the olfaction transmission. Many reports demonstrated calcium elevation in the nasal secretions with a negative effect on olfaction. Sodium gluconate is a water-soluble salt with a chemical structure that lends to act as a highly efficient chelating agent. It can bind the elevated calcium in the nasal secretions reducing the adverse effects on olfactory function.

Objective

To evaluate the impact of intranasal sodium gluconate on decreasing the rise of nasal calcium and improving the sense of smell in patients with olfactory dysfunction post-COVID-19 infection.

Methods

Fifty patients with a history of confirmed COVID-19 suffering from olfactory dysfunction persisted more than 90 days after severe acute respiratory syndrome-coronavirus-2 negative testing were included in a prospective randomized blinded controlled clinical trial. Patients were divided into 2 equal groups, receiving either 0.9% sodium chloride or 1% sodium gluconate. Olfactory function was assessed before treatment and 1 month later using the Sniffin’ Sticks test. Quantitative analysis of the nasal calcium concentration was performed before treatment and 1 month later using a laboratory-designed screen-printed ion-selective electrode.

Results

After using sodium gluconate, the measured olfactory scores indicated a clinical improvement from anosmia to hyposmia compared to the nonimprovement sodium chloride receiving group. Also, a remarked decrease in the calcium nasal concentration was observed after using sodium gluconate compared to sodium chloride.

Conclusion

Based on the proposed results, sodium gluconate may associate with an improvement of the olfactory dysfunction post-COVID-19 infection.

The effect of intra-nasal tetra sodium pyrophosphate on decreasing elevated nasal calcium and improving olfactory function post COVID-19: a randomized controlled trial

Background

Olfactory dysfunction is recognized as a symptom of COVID-19. Reports revealed the nasal calcium increase has adverse effects on olfactory function. Tetra sodium pyrophosphate, a chelating agent, can bind calcium and help improve olfaction.

Methods

Sixty-four patients with olfactory dysfunction persisting for more than 90 days after COVID-19 were recruited. Participants were divided into 2 groups that received either 0.9% sodium chloride or 1% tetra sodium pyrophosphate for topical application. Olfactory function was tested with the Sniffin' Sticks test before treatment and 1 month later. In addition, nasal calcium was determined with an ion-selective electrode.

Results

After topical application of tetra sodium pyrophosphate compared to sodium chloride, improvement from anosmia to hyposmia with decrease in calcium level was demonstrated. As for the results of tetra-sodium pyrophosphate, 81% showed improved olfactory function and 19% did not exhibit olfaction improvement.

Conclusions

Intranasal application of tetra sodium pyrophosphate may be associated with improvement in olfactory function after COVID -19 infection.

Trial registration Ethical Committee of Damietta Faculty of Medicine approved this study on January 2021 (approval number, IRB 00012367-21-03-010).

Effect of intra-nasal nitrilotriacetic acid trisodium salt in lowering elevated calcium cations and improving olfactory dysfunction in COVID-19 patients

Purpose

An association between COVID-19 and olfactory dysfunction has been noted in many patients worldwide. The olfactory adaptation process leads to an increase in intracellular calcium cation levels. Nitrilotriacetic acid trisodium salt has high selective chelation for calcium cations from olfactory mucus. The aim of this work is to test the effect of an intranasal nitrilotriacetic acid trisodium salt to lower the elevated calcium cations in COVID-19 patients with relevant symptoms of olfactory dysfunction.

Methods

Fifty-eight COVID-19 adult patients with relevant symptoms of olfactory dysfunction were enrolled in a prospective randomized controlled trial. They received a nasal spray containing either 0.9% sodium chloride or 2% nitrilotriacetic acid trisodium salt. Olfactory function was assessed before and after treatment using the Sniffin’ Sticks test. Quantitative analysis of calcium cation concentration in nasal secretions was performed using a carbon paste ion-selective electrode.

Results

After the application of nitrilotriacetic acid trisodium salt compared to sodium chloride, a significant improvement from functional anosmia to healthy normosmia with significant decrease in calcium cation concentration was observed.

Conclusions

Further collaborative research is needed to fully investigate the effect of an intranasal nitrilotriacetic acid trisodium salt in the treatment of olfactory disorders.

Riech- und Schmeckstörungen

Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Treatment strategies for postviral olfactory dysfunction: A systematic review

Background: The coronavirus disease 2019 (COVID-19) pandemic has been associated with a dramatic increase in postviral olfactory dysfunction (PVOD) among patients who are infected. A contemporary evidence-based review of current treatment options for PVOD is both timely and relevant to improve patient care. Objective: This review seeks to impact patient care by qualitatively reviewing available evidence in support of medical and procedural treatment options for PVOD. Systematic evaluation of data quality and of the level of evidence was completed to generate current treatment recommendations. Methods: A systematic review was conducted to identify primary studies that evaluated treatment outcomes for PVOD. A number of medical literature data bases were queried from January 1998 to May 2020, with completion of subsequent reference searches of retrieved articles to identify all relevant studies. Validated tools for the assessment of bias among both interventional and observational studies were used to complete quality assessment. The summary level of evidence and associated outcomes were used to generate treatment recommendations. Results: Twenty-two publications were identified for qualitative review. Outcomes of alpha-lipoic acid, intranasal and systemic corticosteroids, minocycline, zinc sulfate, vitamin A, sodium citrate, caroverine, intranasal insulin, theophylline, and Gingko biloba are reported. In addition, outcomes of traditional Chinese acupuncture and olfactory training are reviewed. Conclusion: Several medical and procedural treatments may expedite the return of olfactory function after PVOD. Current evidence supports olfactory training as a first-line intervention. Additional study is required to define specific treatment recommendations and expected outcomes for PVOD in the setting of COVID-19.

Therapies for Olfactory Dysfunction — an Update

Purpose of Review

Olfactory dysfunction is a prevalent condition affecting 5–15% of the general population, with significant impact on quality of life. This review summarizes the most recent and relevant literature in the treatment of olfactory dysfunction.

Recent Findings

Current evidence supports the short-term use of topical corticosteroids and systemic therapy. These treatments may occur in conjunction with olfactory training, which is well supported by the literature. While there are several additional treatments currently under investigation, meaningful conclusions are not yet able to be made regarding their efficacy.

Summary

The treatment of olfactory dysfunction is targeted at the suspected etiology when possible. After normal aging, chronic rhinosinusitis, post-infectious sequelae including as a result SARS-CoV-2 infection (COVID-19), and head trauma are the most common causes. Current evidence supports the short-term use of topical corticosteroids and systemic therapy. Several additional treatments are under investigation but recommendations for their use cannot currently be made.

Graphical abstract

[Olfactory and gustatory disorders]

Ziel der vorliegenden Übersicht ist es, einen Überblick über die Ätiologie und Diagnostik von Riech- und Schmeckstörungen zu geben. Da etwa 5 % der Allgemeinbevölkerung betroffen sind, ist es ein häufiges Krankheitsbild. Riechen und Schmecken erhielten v. a. zuletzt Aufmerksamkeit während des Aufkommens der SARS-CoV-2-Pandemie, wobei eine plötzlich aufgetretene Riech- und/oder Schmeckstörung zu den typischen Symptomen zählt. Daneben sind Riechstörungen in der Frühdiagnostik neurodegenerativer Erkrankungen von Bedeutung. Häufig zeigen Patienten mit Riechstörungen Zeichen einer Depression. Die Auswirkungen von Riech‑/Schmeckstörungen sind also umfangreich, die Therapiemöglichkeiten aktuell begrenzt. Nach einem Einblick in die Ätiologie werden Diagnostik und Therapiemöglichkeiten auf dem aktuellen Stand der Literatur erörtert. Auch zukunftsweisende Behandlungsvorstellungen, wie z. B. autologe Schleimhauttransplantationen oder olfaktorische Implantate, werden angesprochen.

Convolutions in the rendition of nose to brain therapeutics from bench to bedside: Feats & fallacies

Brain, a subtle organ of multifarious nature presents plethora of physiological, metabolic and bio-chemical convolutions that impede the delivery of biomolecules and thereby resulting in truncated therapeutic outcome in pathological conditions of central nervous system (CNS). The absolute bottleneck in the therapeutic management of such devastating CNS ailments is the BBB. Another pitfall is the lack of efficient technological platforms (due to high cost and low approval rates) as well as limited clinical trials (due to failures of neuro‑leads in late-stage pipelines) for CNS disorders which has become a literal brain drain with poorest success rates compared to other therapeutic areas, owing to time consuming processes, tremendous convolutions and conceivable adverse effects. With the advent of intranasal delivery (via direct N2B or indirect nose to blood to brain), several novel drug delivery carriers viz. unmodified or surface modified nanoparticle based carriers, lipid based colloidal nanocarriers and drysolid/liquid/semisolid nanoformulations or delivery platforms have been designed as a means to deliver therapeutic agents (small and large molecules, peptides and proteins, genes) to brain, bypassing BBB for disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, schizophrenia and CNS malignancies primarily glioblastomas. Intranasal application offers drug delivery through both direct and indirect pathways for the peripherally administered psychopharmacological agents to CNS. This route could also be exploited for the repurposing of conventional drugs for new therapeutic uses. The limited clinical translation of intranasal formulations has been primarily due to existence of barriers of mucociliary clearance in the nasal cavity, enzyme degradation and low permeability of the nasal epithelium. The present review literature aims to decipher the new paradigms of nano therapeutic systems employed for specific N2B drug delivery of CNS drugs through in silico complexation studies using rationally chosen mucoadhesive polymers (exhibiting unique physicochemical properties of nanocarrier's i.e. surface modification, prolonging retention time in the nasal cavity, improving penetration ability, and promoting brain specific delivery with biorecognitive ligands) via molecular docking simulations. Further, the review intends to delineate the feats and fallacies associated with N2B delivery approaches by understanding the physiological/anatomical considerations via decoding the intranasal drug delivery pathways or critical factors such as rationale and mechanism of excipients, affecting the permeability of CNS drugs through nasal mucosa as well as better efficacy in terms of brain targeting, brain bioavailability and time to reach the brain. Additionally, extensive emphasis has also been laid on the innovative formulations under preclinical investigation along with their assessment by means of in vitro /ex vivo/in vivo N2B models and current characterization techniques predisposing an efficient intranasal delivery of therapeutics. A critical appraisal of novel technologies, intranasal products or medical devices available commercially has also been presented. Finally, it could be warranted that more reminiscent pharmacokinetic/pharmacodynamic relationships or validated computational models are mandated to obtain effective screening of molecular architecture of drug-polymer-mucin complexes for clinical translation of N2B therapeutic systems from bench to bedside.

Flavor Enhancement in Daily Life of Patients with Olfactory Dysfunction

Introduction

Patients with olfactory dysfunction report deterioration of taste due to loss of flavor, leading to less food enjoyment, alterations in dietary behaviors and stress. The aim of this study was to introduce flavor enhancement to investigate its acceptance and possible effects on quality of life.

Methods

In this prospective, controlled, randomized, single-blinded, cross-over pilot study, we recruited 30 olfactory dysfunction patients, of which 16 were hyposmic and 14 anosmic. After single-blinded triangle flavor discrimination test, flavor drops were randomized either in high or low concentration for 14 days and vice versa for another 14 days. Records included a daily diary and the questionnaire of olfactory disorders.

Results

Usage rates were excellent with 82.2% of all days, while drops were mainly used for breakfast (44.6%, p < 0.05). Hyposmics used flavor enhancement on significantly more days (median = 14) compared to anosmics (median = 11, p = 0.0094). QOD improved in 12 patients to a meaningful extent.

Conclusions

In this pilot study, we show that flavor enhancement is feasible accompanied by high compliance and acceptance in olfactory dysfunction patients. Flavor drops were used regardless of low or high concentrations with no adverse events noted.

Implications

Our findings give rise to further studies illuminating the possible advantages of flavor enhancement in patients with olfactory disorders.

Pathophysiology and possible treatments for olfactory-gustatory disorders in patients affected by COVID-19

SARS-CoV-2 infects host cells mainly through the interaction between the virus's Spike protein and the viral receptors namely Angiotensin-Converting Enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Both are highly expressed in the gastrointestinal tract, in the nasal and bronchial epithelium, as well as in the type II alveolar epithelial cells. The aim of this review is to report the evidences from the scientific literature on the pathophysiology and the available treatments for olfactory-gustatory disorders in patients with COVID-19. The mechanisms involved in these disorders are still unclear and studies on specific therapies are scarce. However, it has been hypothesized that a decrease in the sensitivity of the sensory neurons as well as the co-expression of ACE2 and TMPRSS2 in the alveolar epithelial cells are the main causes of olfactory-gustatory disorders. The possible mechanisms described in the literature for changes in taste perception in patients with COVID-19 include olfactory disorders and a competitive activity of COVID-19 on ACE2 receptors in the taste buds. In addition, SARS-CoV-2 can bind to sialic acid receptors in the taste buds. In general, evidences show that there is no specific treatment for olfactory-taste disorders induced by SARS-CoV-2, even though some treatments have been used and have shown some promising results, such as olfactory training, intranasal application of sodium citrate and vitamin A, as well as systemic use of omega-3 and zinc. Corticosteroids have also been used as a pharmacological approach to treat patients with olfactory dysfunction with some contradictory results. The knowledge of the mechanisms by which SARS-CoV-2 influences the sensory systems and how effective therapies can treat the loss of smell and taste will have important implications on the understanding and clinical management of olfactory-taste disorders.

Intranasal sodium citrate in quantitative and qualitative olfactory dysfunction: results from a prospective, controlled trial of prolonged use in 60 patients

Objectives

We have previously shown that treatment with intranasal sodium citrate may be beneficial in post-infectious olfactory dysfunction. Sodium citrate reduces free intranasal calcium and is, therefore, thought to prevent calcium-mediated feedback inhibition at the level of the olfactory receptor. We aimed to determine whether treatment with a 2-week course of intranasal sodium citrate improves quantitative olfactory function in patients with post-infectious impairment. We also aimed to determine whether sodium citrate is beneficial in treating qualitative olfactory dysfunction.

Methods

We performed a prospective, controlled study. Patients applied intranasal sodium citrate solution to the right nasal cavity for 2 weeks. The left nasal cavity was untreated and, therefore, acted as an internal control. Monorhinal olfactory function was assessed using the “Sniffin’ Sticks” composite ‘TDI’ score, before and after treatment. The presence of parosmia and phantosmia was also assessed.

Results

Overall, there was a significant increase in TDI after treatment (using the best of right and left sides). Treatment with sodium citrate did not significantly improve quantitative olfactory function, compared to control. The proportion of patients reporting parosmia did not change significantly after treatment. However, there was a significant reduction in the proportion of patients reporting phantosmia, at the end of the study period.

Conclusions

Treatment with intranasal sodium citrate for a period of 2 weeks does not appear to improve quantitative olfactory function in patients with post-infectious impairment, compared to control. It may, however, be beneficial in treating phantosmia, which should be further addressed in future work.

Treatment of post-viral olfactory dysfunction: an evidence-based review with recommendations

Background

Post‐viral olfactory dysfunction (PVOD) is one of the most common causes of olfactory loss. Despite its prevalence, optimal treatment strategies remain unclear. This article provides a comprehensive review of PVOD treatment options and provides evidence‐based recommendations for their use.

Methods

A systematic review of the Medline, Embase, Cochrane, Web of Science, Scopus, and Google Scholar databases was completed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Studies with defined olfactory outcomes of patients treated for PVOD following medical, surgical, acupuncture, or olfactory training interventions were included. The Clinical Practice Guideline Development Manual and Conference on Guideline Standardization (COGS) instrument recommendations were followed in accordance with a previously described, rigorous, iterative process to create an evidence‐based review with recommendations.

Results

From 552 initial candidate articles, 36 studies with data for 2183 patients with PVOD were ultimately included. The most common method to assess olfactory outcomes was Sniffin’ Sticks. Broad treatment categories included: olfactory training, systemic steroids, topical therapies, a variety of heterogeneous non‐steroidal oral medications, and acupuncture.

Conclusion

Based on the available evidence, olfactory training is a recommendation for the treatment of PVOD. The use of short‐term systemic and/or topical steroids is an option in select patients after careful consideration of potential risks of oral steroids. Though some pharmacological investigations offer promising preliminary results for systemic and topical medications alike, a paucity of high‐quality studies limits the ability to make meaningful evidence‐based recommendations for the use of these therapies for the treatment of PVOD.

Patient-recorded benefit from nasal closure in a Danish cohort of patients with hereditary haemorrhagic telangiectasia

BACKGROUND

Nasal closure, also known as the modified Young's procedure was introduced in Denmark in 2008, as a surgical solution to severe epistaxis in patients with hereditary haemorrhagic telangiectasia (HHT). The objective of this study was to report the overall satisfaction of the procedure from a patient's point of view as well as the occurrence of complications.

METHODS

All the HHT patients who underwent nasal closure from 2008 to 2018 were included in the study. The patients were evaluated for postoperative complications and subjective outcome using Glasgow Benefit Inventory (GBI).

RESULTS

Ten patients were included in the study and were observed for a mean of 64 months. None of the patients was completely free of complications, and reversal was requested in a single case. Haemoglobin levels rose with an average of 2.8 g/dl. The average GBI score after surgery was 38.05. Nine of ten patients would recommend nasal closure to fellow HHT patients.

CONCLUSION

Nasal closure is highly recommended among patients, but due to the rate of postoperative complications, the procedure should be reserved for a carefully selected group of HHT patients.

Citrate- and Succinate-Modified Carbonate Apatite Nanoparticles with Loaded Doxorubicin Exhibit Potent Anticancer Activity against Breast Cancer Cells

Biodegradable inorganic apatite-based particle complex is popular for its pH-sensitivity at the endosomal acidic environment to facilitate drug release following cellular uptake. Despite being a powerful anticancer drug, doxorubicin shows severe off-target effects and therefore would need a carrier for the highest effectiveness. We aimed to chemically modify carbonate apatite (CA) with Krebs cycle intermediates, such as citrate and succinate in order to control the growth of the resultant particles to more efficiently carry and transport the anticancer drug into the cancer cells. Citrate- or succinate-modified CA particles were synthesized with different concentrations of sodium citrate or sodium succinate, respectively, in the absence or presence of doxorubicin. The drug loading efficiency of the particles and their cellular uptake were observed by quantifying fluorescence intensity. The average diameter and surface charge of the particles were determined using Zetasizer. Cell viability was assessed by MTT assay. Citrate-modified carbonate apatite (CMCA) exhibited the highest (31.38%) binding affinity for doxorubicin and promoted rapid cellular uptake of the drug, leading to the half-maximal inhibitory concentration 1000 times less than that of the free drug in MCF-7 cells. Hence, CMCA nanoparticles with greater surface area enhance cytotoxicity in different breast cancer cells by enabling higher loading and more efficient cellular uptake of the drug.

Anosmia-A Clinical Review

Anosmia and hyposmia, the inability or decreased ability to smell, is estimated to afflict 3-20% of the population. Risk of olfactory dysfunction increases with old age and may also result from chronic sinonasal diseases, severe head trauma, and upper respiratory infections, or neurodegenerative diseases. These disorders impair the ability to sense warning odors in foods and the environment, as well as hinder the quality of life related to social interactions, eating, and feelings of well-being. This article reports and extends on a clinical update commencing at the 2016 Association for Chemoreception Sciences annual meeting. Included were reports from: a patient perspective on losing the sense of smell with information on Fifth Sense, a nonprofit advocacy organization for patients with olfactory disorders; an otolaryngologist's review of clinical evaluation, diagnosis, and management/treatment of anosmia; and researchers' review of recent advances in potential anosmia treatments from fundamental science, in animal, cellular, or genetic models. As limited evidence-based treatments exist for anosmia, dissemination of information on anosmia-related health risks is needed. This could include feasible and useful screening measures for olfactory dysfunction, appropriate clinical evaluation, and patient counseling to avoid harm as well as manage health and quality of life with anosmia.