flo travel nasal spray covid

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To help aid natural nasal immunity against cold viruses, bacteria, and irritants, try FLO Travel nasal spray. A preservative-free, isotonic, and moisturising nasal spray that helps the nose’s natural action to clear excess mucus containing viruses, bacteria and allergens from the nose.

How can FLO Travel Nasal Spray help?

Travelling in low humidity and air conditioning can result in a dry nose and increased susceptibility to airborne irritants, viruses and bacteria. Carrageenan (red seaweed extract) binds to nasal tissues, forming a protective layer, which helps retain moisture for hours. Carrageenan also has a virus-trapping capability, binding to many viruses that cause the common cold. The risk of infection and virus spread may be reduced due to this binding action

FLO Travel Nasal Spray helps to:

• Wash away bacteria, viruses, and nasal irritants
• Keeps nasal tissue hydrated to minimise nasal dryness and crusting
• Aids in natural nasal immunity against cold viruses, bacteria, and irritants

ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE

• Prime the pump then insert the nozzle into your nostril
• For optimal coverage, angle the nozzle towards the earlobe on the same side as the nostril being treated
• Spray as many times as required to deliver the recommended dose
• Repeat this process with the other nostril.
• After use clean nozzle with soapy water, rinse with warm water and dry with a clean tissue. Replace protective cap.

Dosage Information

Adults and children over 12 years : up to 2 sprays per nostril

Children 2 to 12 years of age : 1 spray per nostril

Use more frequently to relieve nasal dryness if required

Suitable for use in pregnancy and while breastfeeding

Breathe freely with FLO

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Adults and children over 2 years of age can use FLO Travel Nasal Spray before, during and after travelling (or more frequently if required) to aid natural nasal immunity against inhaled bacteria, cold viruses and irritants.

• Adults and children over 12 years of age can use up to 2 sprays per nostril, 3 times a day
• Children between 2 and 12 years of age should only be given 1 spray per nostril, up to 3 times

ALWAYS READ THE LABEL AND FOLLOW DIRECTIONS FOR USE

BREATHE FREELY WITH FLO

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Nasal Sprays Could Protect You From Serious COVID-19 Illness

Getty Images / Jennifer A Smith

Key Takeaways

• A study shows that people using corticosteroid sprays who contracted COVID-19 generally had less severe outcomes.
• These nasal sprays are available over the counter and are relatively inexpensive. 
• The study is observational; researchers need to conduct clinical trials to know whether whether this is a safe and effective COVID-19 prevention approach.

Nasal steroid sprays may reduce the severity of COVID-19, according to a new study.

Researchers found that for people who regularly used a prescription corticosteroid like Beconase or Nasonex before getting sick with COVID-19, the risk of severe outcomes like hospitalization and death dropped by as much as 25%.

The study, which was published in August in The Journal of Allergy and Clinical Immunology: In Practice, is a retrospective report.

If the approach holds up in clinical studies, these steroids could be used to prevent serious COVID-19 outcomes and support the survival of the sickest patients, says Ronald Strauss, MS, MD , an allergist-immunologist and Director of the Cleveland Allergy and Asthma Center, and a lead author of the study.

“This would be something to add to the armamentarium besides the COVID vaccine. It’s certainly not recommended instead of it,” Strauss tells Verywell. “Depending on what the studies show, it might be something to send throughout the world in areas in Africa and other countries where the immunizations are not available to mitigate the severity of COVID-19.”

To understand the role of corticosteroids on COVID-19 outcomes, the researchers analyzed data from the Cleveland Clinic COVID-19 Research Registry on 72,147 adults who tested positive for COVID-19 between spring 2020 and spring 2021.  

Among these people, over 10,000 patients were using prescription nasal sprays before becoming infected with COVID-19. For this group, the risk of hospitalization decreased 22%, admissions to the intensive care unit fell 23%, and mortality dropped 24%.

The numbers support earlier lab-based studies which indicate that steroids may help prevent SARS-CoV-2—the virus that causes COVID-19—from entering cells in the nasal passageways .

How It Works

Using nasal steroids before and during COVID-19 infection might disrupt the virus’s ability to breach an important gateway: nasal passages. The nose has a large concentration of ACE2, a protein on certain human cells that serves as a dock for the virus, allowing it to infect and replicate . Because of this, the nasal passageway is a “major portal of entry” for the virus, the authors write.

“The theory was—and is now since we have these positive results—that if you can decrease ACE2 protein, that means there are fewer cells that can be infected with the virus, which would hopefully then lead to less severe COVID,” Strauss says.

The reported impact of nasal sprays on COVID-19 outcomes is promising, but a randomized clinical trial is necessary to definitely say that this approach is safe and effective for widespread use.

“It’s a potentially game-changing approach, but I think we probably want a bit more conclusive clinical trial data before we could say that definitely,” Aran Singanayagam, PhD , a professor of medicine at Imperial College London who is not affiliated with the study, tells Verywell.

Ronald Strauss, MS, MD

One of the definitive things we can say from our study is that if you’re on a nasal steroid, stay on it. It’s not going to make the COVID any worse and the essence of this study is that it can only help.

Inhaled Steroids Could Have a Similar Effect

Inhaled corticosteroids work similarly to nasal sprays. This medication—often administered via devices like inhalers—can be used to treat pulmonary conditions like asthma and bronchitis.

Corticosteroids work by broadly suppressing inflammation where they are introduced. Inhaled steroids, for instance, sooth inflammation in the lungs. Some of the most severe outcomes of COVID-19, like respiratory failure, arise when the immune system kicks into high gear, triggering inflammation in organs like the lungs. Minimizing hyperinflammation can limit serious illness in infected patients.

Corticosteroids may also block the virus from infecting cells. Singanayagam’s team published a study earlier this year showing that steroid inhalers reduced the number of ACE2 receptors in animal models and human cells.

Researchers are working to better understand the different forms of ACE2 and how to engineer a steroid that can better target the virus.  

“We probably want a more targeted drug that retains some of the benefits of steroids but don’t broadly suppress the immune system,” Singanayagam says.

According to the National Institutes of Health , there is insufficient data to recommend the use of inhaled corticosteroids. Dexamethasone, which comes as an oral pill or solution, is the only corticosteroid currently recommended for use against COVID-19 in hospitalized patients.

Should You Start Using a Nasal Spray?

Nasal sprays are relatively inexpensive and easy to access, meaning they could become a key COVID-19 treatment option, especially in low- and middle-income countries where vaccination rates are low.

But don’t go running to the pharmacy for Flonase just yet, Singanayam says. The over-the-counter medications don’t have any contraindications, but clinical studies have yet to show that they are safe and effective as COVID-19 treatments.

The same holds true for inhaled steroids.

“You shouldn’t be on inhaled steroids if you don’t have asthma or COPD,” Singanayam adds.

If you already regularly take a nasal steroid, however, it’s likely that it can support your body in protecting against COVID-19.

“One of the definitive things we can say from our study is that if you’re on a nasal steroid, stay on it. It’s not going to make the COVID any worse and the essence of this study is that it can only help,” Strauss says.

What This Means For You

If you already use a nasal spray for seasonal allergies or other needs, you may be slightly protected against severe COVID-19 outcomes. If not, it's best not to start until clinical studies verify that they are safe and effective. Health experts emphasize that vaccination is still the best way to protect yourself from serious COVID-19.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our  coronavirus news page .

Strauss R, Jawhari N, Attaway AH, et al. I ntranasal corticosteroids are associated with better outcomes in coronavirus disease 2019 [published online ahead of print, 2021 Aug 23] .  J Allergy Clin Immunol Pract . 2021;S2213-2198(21)00906-5. doi:10.1016/j.jaip.2021.08.007

Finney LJ, Glanville N, Farne H, et al. Inhaled corticosteroids downregulate the SARS-CoV-2 receptor ACE2 in COPD through suppression of type I interferon .  Journal of Allergy and Clinical Immunology . 2021;147(2):510-519.e5.

doi:10.1016/j.jaci.2020.09.034.

By Claire Bugos Bugos is a senior news reporter at Verywell Health. She holds a bachelor's degree in journalism from Northwestern University.

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Consumer medicine information

Flo travel nasal spray.

Carrageenan

Keep track of your medicines

BRAND INFORMATION

Active ingredient

Unscheduled

Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using FLO Travel Nasal Spray.

• Download CMI (PDF)
• Download Large Text CMI (PDF)

What you should know about your nose

Mucus is naturally produced in the nose and its role is to trap foreign particles (dust, viruses and bacteria) and keep them from getting into the lungs. Mucus is transported from the front of the nose and from within the sinuses by tiny microscopic hairs called "cilia" which sweep the mucus to the back of the throat from where it is swallowed.

The acid environment in the stomach then helps to kill unwanted bacteria and viruses. This is an important function of the body's immune system and it helps to maintain good health.

What happens when the mucus layer becomes dry?

When mucus dries out it becomes thicker and the cilia hairs cannot function as well as they should. This may cause a feeling of nasal discomfort.

Travelling in low humidity and cool environments

Spending prolonged periods of time in low humidity and cool environments (such as aircraft cabins, buses, trains and hotels with air conditioning) has been shown to dry nasal mucus and slow the normal movement of mucus. This may lead to an increased susceptibility to infections and travellers getting colds more easily than they would otherwise do.

What is FLO Travel Nasal Spray?

FLO Travel Nasal Spray is a sterile, preservative free saline spray containing Carrageenan 1.6mg /mL (1.2mg/mL iota-Carrageenan and 0.4mg/mL kappa-Carrageenan). It is a clear, colourless and odourless solution.

Carrageenan is an extract derived from marine red algae. Carrageenan binds effectively to mucus and strongly attracts water. This helps keep the nasal tissues moist to prevent and relieve symptoms of nasal discomfort that can be experienced on long distance flights, and importantly also helps nasal tissue to function normally to keep you healthy.

In the event of contracting a cold, Carrageenan has been shown to help reduce the length of time cold symptoms are experienced. This can be an added advantage when travelling.

How to use FLO Travel Nasal Spray

This dispenser should be used by only one person. Sharing it may spread infection.

• Before using this product, remove the protective cap and prime the pump by depressing the round flange several times until the first spray is seen.
• Place the nozzle carefully into one nostril with the tip pointing towards the top of the ear on the same side of the head (the tip should be pointing backwards and slightly angled away from the midline of the nose).
• Depress the pump to insert the required dose into the nostril while gently breathing in through the nose as you spray.
• Repeat for the other nostril.
• Wipe the nozzle with a clean tissue and replace protective cap after use.
• Store this product out of the sight and reach of children.

Dose to be applied to each nostril:

• Adults and children over 2 years: one spray three times daily.

This product may be used:

a)before, during and after travel.

b) more frequently if required to relieve nasal dryness.

Always drink adequate fluids and remember to take part in recommended exercise programmes on long journeys.

Pregnancy and Breast Feeding

FLO Travel is non-medicated and can be used during pregnancy and whilst breast feeding.

How long can FLO Travel be used?

FLO Travel nasal spray may be used for as long as necessary.

If nasal symptoms persist see your healthcare practitioner.

When not to use FLO Travel Nasal Spray

You should not use FLO Travel if you have any sensitivity to sodium chloride or Carrageenan. If you experience any unexpected effects when using this product, stop using it and see your healthcare practitioner.

When does FLO Travel expire?

FLO Travel has an expiry date which can be found on the carton and also on the bottle label. Do not use the product after this expiry date.

Due to its special filter system, the solution remains sterile even after repeated use.

Discard 12 months after date of first use.

Can FLO Travel be used with other medication?

FLO Travel is a non-medicated product. If you have any concerns about using FLO Travel with your current medications, please consult your healthcare practitioner.

Packaging and Storage

FLO Travel Nasal Spray is packaged in a dark brown glass bottle containing 20mL of solution. Each spray delivers 0.14mL of solution.

The outer carton is sealed with tabs on the top and bottom flaps. You should not use this product if any of these tabs have been removed or damaged at the time of purchase.

Store the product in its carton to protect it from light.

Store the product below 30°C. Do not refrigerate.

Keep out of reach of children.

For more information, contact:

ENT Technologies Pty Ltd Suite 304, 12 Cato Street Hawthorn East, VIC 3123. Australia. Phone +61 3 9832 3700 or local call 1300 857 912 www.flo.com.au

Manufacturer: Hälsa Pharma GmbH Maria-Goeppert-Straẞe 5, 23562 Lübeck. GERMANY.

Last update June 2022.

Published by MIMS May 2024

Name of the medicine

Carrageenan in sterile physiological saline.

Description

Flo Travel nasal spray contains 1.6 mg/mL of carrageenan in sterile physiological saline.

Pharmacology

Carrageenan is an extract of red seaweed (Chondrus crispus) and consists of both iota and kappa forms. Both these types of carrageenan have gelling properties and have been used for many years in the food industry. Carrageenan is strongly anionic which accounts for its mucoadhesive properties. It is also very hygroscopic and strongly retains water. Iota carrageenans have been shown to have antiviral properties against common cold viruses (rhinovirus, corona virus and influenza A) 1,2 . They have been shown to shorten the duration of colds, to reduce the severity of symptoms and also the period of viral shedding. Environments which are kept cool to cold and which have a low humidity are challenging to nasal mucosal function. Mucus has been demonstrated to thicken and cilial beat frequency to decrease. As a result mucociliary transport is delayed 3 . This may have deleterious effects on the antimicrobial efficacy of the upper airway. Thickened mucus can become crusty and uncomfortable for people exposed to these environments for prolonged periods of time. With the added microbial pressures of close confines with other passengers or workers viral infections may be experienced more frequently. As a solution to address these issues, carrageenan offers topical protection for nasal mucosa as well as the added benefits of antiviral properties.

Indications

Flo Travel is indicated for the prevention and relief of nasal crusting and dryness when there is prolonged exposure to cold and low humidity environments. These are experienced on aeroplane journeys, in office and hotel environments and wherever air conditioning is in constant use. It may also be used to shorten the duration and severity of common cold symptoms.

Contraindications

1. Sensitivity to any of the ingredients (carrageenans or saline solutions). 2. Nasal congestion or irritation associated with use of Flo Travel. 3. If any of the tamper evident seals are missing or show evidence of tampering.

Precautions

Use in pregnancy., use in lactation., interactions, use with other medications., dosage and administration, adults and children over 12 years., children 2 years of age and older., method of use., presentation.

Nasal spray (preservative free, colourless, tasteless sterile solution), 1.6 mg/mL, 20 mL (0.14 mL/spray): 1's (dark brown glass bottle).

Store between 5 and 30 degrees Celsius in the original outer packaging. Do not refrigerate. Keep out of sight and reach of children.

1. Review of Carrageenan based pharmaceutical biomaterials: Favourable physical features versus adverse biological effects. Liu J et al. Carbohydrate Polymers Vol 121(2015) pp 27-36. 2. Carrageenan nasal spray in virus confirmed common cold: individual patient data analysis of two randomised controlled trials. Koenighofer M et al Multidisciplinary Respiratory Medicine (2014) Vol 9; pp 57-69. 3. Exposure to cold and acute upper respiratory tract infection. Eccles R et al Rhinology (2015) Vol 53 pp 99-106.

Poison Schedule

Unscheduled.

Date published: 07 June 2022

Reasonable care is taken to provide accurate information at the time of creation. This information is not intended as a substitute for medical advice and should not be exclusively relied on to manage or diagnose a medical condition. NPS MedicineWise disclaims all liability (including for negligence) for any loss, damage or injury resulting from reliance on or use of this information. Read our full disclaimer . This website uses cookies. Read our privacy policy .

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Flo Travel Nasal Spray

FLO Travel is a preservative free, isotonic saline nasal spray containing Carrageenan (red seaweed extract). FLO Travel helps to keep nasal tissue hydrated which aids in natural nasal immunity and increases the rate of recovery from colds due to Coronavir

Product Information

FLO Travel is a preservative free, isotonic saline nasal spray containing Carrageenan (red seaweed extract). FLO Travel helps to keep nasal tissue hydrated which aids in natural nasal immunity and increase the rate of recovery from colds due to Coronaviruses, Rhinoviruses and Influenza viruses. <br /> <br /> Using FLO Travel relieves nasal dryness which supports the nose&rsquo;s natural action to protect against colds and viruses., making it beneficial to use while travelling.<br /> <br /> FLO Travel to protect and support nasal health and shortens &amp; reduces cold symptoms. It is best to use in air-conditioned environments, when prone to colds and when suffering cold symptoms.

Ingredients

Sodium Chloride, Carrageenan 1.6mg/mL

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Flo Travel Nasal Spray 20mL › Customer reviews

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Flo Travel Nasal Spray 20mL

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Dr Lara Herrero

Will COVID nasal sprays soon help prevent and treat infection?

Lara Herrero

Virology and infectious diseases expert Dr Lara Herrero looks at the latest science surrounding a potential new treatment.

We have vaccines to boost our immune response to SARS-CoV-2, the virus that causes COVID. We have medicines you can take at home (and in hospital) to treat COVID. Now researchers are trialling something new.   They want to develop drugs that stop the virus getting into the body in the first place. That includes nasal sprays that stop the virus attaching to cells in the nose.   Other researchers are looking at the potential for nasal sprays to stop the virus replicating in the nose, or to make the nose a hostile place to enter the body.   Here’s where the science is up to and what we can expect next.   How could we block the virus? ‘Viral blockade’, as the name suggests, is a simple premise based on blocking SARS-CoV-2. In other words, if something gets in its way, the virus cannot attach to a cell and it can’t infect you.   As SARS-CoV-2 is a respiratory virus, it makes sense to deliver this type of medicine where the virus mainly enters the body – via the nose, in a nasal spray.   There are various groups around the world working on this concept. Some research is still being conducted in the lab. Some agents have progressed to preliminary human trials. None are yet available for widespread use.   Heparin Heparin is a common medicine that’s been used for decades to thin the blood. Studies in mice show that when heparin is delivered via the nose,  it’s safe  and  effective  in preventing the virus binding to nose cells.   Researchers believe heparin binds to the virus itself and stops the virus attaching to the cells it’s trying to infect. A  clinical trial  is being  conducted in Victoria  in collaboration between multiple Melbourne-based research centres and the University of Oxford.   Covixyl-V Covixyl-V (ethyl lauroyl arginine hydrochloride) is another nasal spray  under development . It aims to prevent COVID by blocking or modifying the cell surface to prevent the virus from infecting.   This compound has been explored for use in various viral infections, and  early studies  in cells and small animals have shown it can prevent attachment of SARS-CoV-2 and reduce the overall viral load.   Iota-carrageenan This molecule, which is extracted from seaweed, acts by blocking virus entry into  airway cells .   One study of about 400 healthcare workers suggests a nasal spray may reduce the incidence of COVID  by up to 80% .   IGM-6268 This is  an engineered antibody  that binds to SARS-CoV-2,  blocking  the virus from attaching to cells in the nose.   A nasal and oral (mouth) spray are in a clinical trial  to assess safety .   Cold atmospheric plasma This is a gas that contains charged particles. At cold temperatures, it can  alter the surface  of a cell.   A  lab-based study  shows the gas changes expression of receptors on the skin that would normally allow the virus to attach. This results in less SARS-CoV-2 attachment and infection.   Scientists now think this technology could be adapted to a nasal spray to prevent SARS-CoV-2 infection.   How could we stop the virus replicating? Another tactic is to develop nasal sprays that stop the virus replicating in the nose.   Researchers are designing genetic fragments that bind to the viral RNA. These fragments – known as ‘ locked nucleic acid antisense oligonucleotides ’ (or LNA ASOs for short) – put a proverbial spanner in the works and stop the virus from replicating.   A spray of these genetic fragments delivered into the nose  reduced virus replication in the nose  and prevented disease in small animals.   How could we change the nose? A third strategy is to change the nose environment to make it less hospitable for the virus.   That could be by using a nasal spray to change moisture levels (with saline), alter the pH (making the nose more acidic or alkaline), or adding a virus-killing agent (iodine).   Saline can reduce the amount of  SARS-CoV-2 in the nose  by simply washing away the virus. One study has even found that saline nasal irrigation  can lessen COVID disease  severity. But we would need further research into saline sprays.   An Australian-led study has found that an iodine-based nasal spray  reduced the viral load  in the nose. Further  clinical trials  are planned.   One study  used a test spray – containing ingredients including eucalyptus and clove oils, potassium chloride and glycerol. The aim was to kill the virus and change the acidity of the nose to prevent the virus attaching.   This novel formulation has been tested in the lab and in a  clinical trial  showing it to be safe and to reduce infection rate from about 34% to 13% when compared to placebo controls.   Barriers ahead Despite promising data so far on nasal sprays for COVID, one of the  major barriers  is keeping the sprays in the nose.   To overcome this, most sprays need multiple applications a day, sometimes every few hours.   So based on what we know so far, nasal sprays will not singlehandedly beat COVID. But if they are shown to be safe and effective in clinical trials, and receive regulatory approval, they might be another tool to help prevent it.   This article originally appeared in The Conversation . Read the original article .   Log in below to join the conversation.

COVID-19 nasal spray SARS-CoV-2

First real-world studies on COVID-19 oral antivirals emerge

What is the latest on covid-19 treatments available in australia.

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Nasal spray shown to be effective in reducing COVID-19 transmission

Posted: 5 May 2021 | Hannah Balfour (European Pharmaceutical Review) | 2 comments

The algae-derived Nasitrol TM nasal spray reduced the incidence of COVID-19 in intensive care unit (ICU) workers to one percent in a clinical trial.

According to Amcyte Pharma, its Nasitrol TM  nasal spray was shown to be effective in reducing COVID-19 infections among intensive care unit (ICU) staff in an independent clinical trial.

Nasitrol is a patented nasal spray based on iota carrageenan, a sulfate polysaccharide synthesised by red algae, with demonstrated antiviral activity and clinical efficacy as a nasal spray in the treatment of the common cold. A previous study at the US’s University of Tennessee Health Science Center found that the formulation inhibits infection by SARS-CoV-2, the virus that causes COVID-19, in vitro .

In the new study ( NCT04590365 ), conducted at eight hospital ICUs in 394 clinically healthy physicians, nurses and other medical professionals who provided care to COVID-19 patients and who had not yet been vaccinated against the disease. The participants were randomly assigned to receive four daily doses of Nasitrol spray or placebo for 21 days. The primary end point was clinical COVID-19 infection, as confirmed by reverse-transcriptase-polymerase-chain-reaction (RT_PCR) testing, over 21 days.

The incidence of COVID-19 infection was significantly lower in the Nasitrol group compared with placebo, one percent versus five percent, respectively. 

The study was led by Dr Juan Figueroa of The Cesar Milstein Research Institute in Argentina and Dr Mónica Lombardo of the CEMIC University Hospital in Buenos Aires, and sponsored by the Ministry of Science, Technology and Innovation of Argentina.

“This rigorous, placebo-controlled study provides evidence that the simple intervention of a nasal spray with iota-carrageenan, in addition to hand hygiene, use of personal protective equipment and social distancing, could provide additional protection against transmission,” stated Dr Gustavo Mahler, Chief Executive Officer of Amcyte Pharma. “We look forward to partnering and commercialising Nasitrol in the US so that healthcare professionals, caregivers for COVID patients and other individuals who are at risk can benefit.”

Nasitrol mechanism of action

The nasal cavity and the rhinopharynx are key sites of the initial replication of SARS-CoV-2. Its active substance, iota-carrageenan, is thought to exert anti-viral activity through its interaction with the viral surface, preventing viral entry and capturing viral particles released by infected cells. The spray is formulated to reduce the viral load in upper respiratory airways, preventing viruses from proliferating and spreading into the lungs.

New Finnish company to develop a nasal spray vaccine for COVID-19…

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Clinical Trials , Drug Delivery Systems , Drug Development , Drug Safety , Drug Targets , Research & Development (R&D) , Therapeutics , Viruses

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Dr Gustavo Mahler , Dr Juan Figueroa , Dr Mónica Lombardo

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Coronavirus , Covid-19

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2 responses to “Nasal spray shown to be effective in reducing COVID-19 transmission”

The title of your paper is wrong or I do not understand. Is COVID-19 being transmitted or the SARS COV-2 virus? I thought that the first one is the sickness the 2nd one is causing? Can the sickness also be transmitted?

Hi Leopoldo, You are right, the SARS-CoV-2 virus is what is transmitted and thus causes the COVID-19 disease. It is also correct to say COVID-19 transmission – as in COVID-19 transmission rate, which refers to the spread of the disease. I’ll bear in mind for the next article to use ‘spread of COVID-19’ instead.

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Analysis COVID-19 nasal sprays may one day prevent and treat infection. Here’s where the science is up to

We have vaccines to boost our immune response to SARS-CoV-2, the virus that causes COVID-19. We have medicines you can take at home (and in hospital) to treat COVID-19. Now researchers are trialling something new.

They want to develop drugs that stop the virus getting into the body in the first place. That includes nasal sprays that stop the virus attaching to cells in the nose.

Other researchers are looking at the potential for nasal sprays to stop the virus replicating in the nose, or to make the nose a hostile place to enter the body.

Here's where the science is up to and what we can expect next.

How could we block the virus?

"Viral blockade", as the name suggests, is a simple premise based on blocking SARS-CoV-2. In other words, if something gets in its way, the virus cannot attach to a cell and it can't infect you.

As SARS-CoV-2 is a respiratory virus, it makes sense to deliver this type of medicine where the virus mainly enters the body – via the nose, in a nasal spray.

There are various groups around the world working on this concept. Some research is still being conducted in the lab. Some agents have progressed to preliminary human trials. None are yet available for widespread use.

Heparin is a common medicine that's been used for decades to thin the blood. Studies in mice show that when heparin is delivered via the nose,  it’s safe and effective  in preventing the virus binding to nose cells. Researchers believe heparin binds to the virus itself and stops the virus attaching to the cells it's trying to infect.

A clinical trial  is being conducted in Victoria in collaboration between multiple Melbourne-based research centres and the University of Oxford.

Covixyl-V (ethyl lauroyl arginine hydrochloride) is another nasal spray under development . It aims to prevent COVID-19 by blocking or modifying the cell surface to prevent the virus from infecting.

This compound has been explored for use in various viral infections, and early studies in cells and small animals has shown it can prevent attachment of SARS-CoV-2 and reduce the overall viral load.

Iota-carrageenan

This molecule, which is extracted from seaweed, acts by blocking virus entry into airway cells.

One study of about 400 health-care workers suggests a nasal spray may reduce the incidence of COVID-19 by up to 80 per cent.

This is an engineered antibody that binds to SARS-CoV-2, blocking the virus from attaching to cells in the nose.

A nasal and oral (mouth) spray are in a clinical trial to assess safety.

Cold atmospheric plasma

This is a gas that contains charged particles. At cold temperatures, it can alter the surface of a cell.

A lab-based study shows the gas changes expression of receptors on the skin that would normally allow the virus to attach. This results in less SARS-CoV-2 attachment and infection.

Scientists now think this technology could be adapted to a nasal spray to prevent SARS-CoV-2 infection.

How could we stop the virus replicating?

Another tactic is to develop nasal sprays that stop the virus replicating in the nose.

Researchers are designing genetic fragments that bind to the viral RNA. These fragments – known as "locked nucleic acid antisense oligonucleotides" (or LNA ASOs for short) – put a proverbial spanner in the works and stop the virus from replicating.

A spray of these genetic fragments delivered into the nose reduced virus replication in the nose and prevented disease in small animals.

How could we change the nose?

A third strategy is to change the nose environment to make it less hospitable for the virus.

That could be by using a nasal spray to change moisture levels (with saline), alter the pH (making the nose more acidic or alkaline), or adding a virus-killing agent (iodine).

Saline can reduce the amount of SARS-CoV-2 in the nose by simply washing away the virus. One study has even found that saline nasal irrigation can can lessen COVID disease  severity. But we would need further research into saline sprays.

An Australian-led study has found that an iodine-based nasal spray reduced the viral load in the nose. Further  clinical trials are planned.

One study used a test spray — containing ingredients including eucalyptus and clove oils, potassium chloride and glycerol. The aim was to kill the virus and change the acidity of the nose to prevent the virus attaching.

This novel formulation has been tested in the lab and in a clinical trial showing it to be safe and to reduce infection rate from about 34 per cent to 13 per cent when compared to placebo controls.

Barriers ahead

Despite promising data so far on nasal sprays for COVID-19, one of the major barriers is keeping the sprays in the nose.

To overcome this, most sprays need multiple applications a day, sometimes every few hours.

So based on what we know so far, nasal sprays will not single-handedly beat COVID-19. But if they are shown to be safe and effective in clinical trials, and receive regulatory approval, they might be another tool to help prevent it.

Lara Herrero is a research leader in virology and infectious disease at Griffith University. This piece first appeared on The Conversation .

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Fluticasone propionate as a potential treatment for COVID-19

Affiliation.

• 1 Weill Cornell Medicine College, New York City, New York, USA. [email protected].
• PMID: 35535815
• DOI: 10.1358/dot.2022.58.5.3381591

Outpatient treatment options for mild to moderate COVID-19 are severely limited. While many therapeutic options have been proposed, very few have demonstrated the appropriate safety and efficacy to warrant approval by national or international regulatory bodies. Monoclonal antibodies have been shown to decrease hospitalization in high-risk patients, but use remains limited due to challenges associated with both production and administration, and other treatment options are urgently needed. The anti-inflammatory drug fluticasone propionate has recently emerged as a potential outpatient treatment option, especially for those with newly diagnosed disease. This manuscript reviews what is known about fluticasone and looks ahead to examine how the drug may be used in the future to address the COVID-19 pandemic.

Keywords: COVID-19; Drug repurposing; Fluticasone propionate; Glucocorticoid receptor agonists; Inhaled corticosteroids; SARS-CoV-2 infection.

Copyright 2022 Clarivate.

• Administration, Inhalation
• Androstadienes / adverse effects
• Anti-Asthmatic Agents* / adverse effects
• Asthma* / drug therapy
• COVID-19 Drug Treatment*
• Double-Blind Method
• Fluticasone / adverse effects
• Androstadienes
• Anti-Asthmatic Agents
• Fluticasone

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Drug-Free Nasal Spray as a Barrier against SARS-CoV-2 and Its Delta Variant: In Vitro Study of Safety and Efficacy in Human Nasal Airway Epithelia

1 Altamira Medica AG, 6300 Zug, Switzerland; moc.scitueparehtarimatla@faf (F.F.); moc.lacidemsirua@jr (R.J.); moc.lacidemsirua@fev (V.F.)

Reda Juskeviciene

Veronica francardo, stéphanie mateos.

2 Texcell SA, 91000 Evry, France; rf.llecxet@soetam (S.M.); rf.llecxet@aleunam (M.G.); rf.llecxet@telloivc (C.V.)

Manuela Guyard

Cécile viollet, samuel constant.

3 Epithelix Sarl, 1228 Geneva, Switzerland; [email protected]

Massimo Borelli

4 Life Sciences and Technologies Department, School of PhD Programmes, Magna Graecia University, 88100 Catanzaro, Italy; [email protected]

Ilja P. Hohenfeld

Associated data.

Data are included in the article.

The nasal epithelium is a key portal for infection by respiratory viruses such as SARS-CoV-2 and represents an important target for prophylactic and therapeutic interventions. In the present study, we test the safety and efficacy of a newly developed nasal spray (AM-301, marketed as Bentrio) against infection by SARS-CoV-2 and its Delta variant on an in vitro 3D-model of the primary human nasal airway epithelium. Safety was assessed in assays for tight junction integrity, cytotoxicity and cilia beating frequency. Efficacy against SARS-CoV-2 infection was evaluated in pre-viral load and post-viral load application on airway epithelium. No toxic effects of AM-301 on the nasal epithelium were found. Prophylactic treatment with AM-301 significantly reduced viral titer vs. controls over 4 days, reaching a maximum reduction of 99% in case of infection from the wild-type SARS-CoV-2 variant and more than 83% in case of the Delta variant. When AM-301 administration was started 24 h after infection, viral titer was reduced by about 12-folds and 3-folds on Day 4. The results suggest that AM-301 is safe and significantly decelerates SARS-CoV-2 replication in cell culture inhibition assays of prophylaxis (pre-viral load application) and mitigation (post-viral load application). Its physical (non-pharmaceutical) mechanism of action, safety and efficacy warrant additional investigations both in vitro and in vivo for safety and efficacy against a broad spectrum of airborne viruses and allergens.

1. Introduction

The COVID-19 pandemic has had a massive toll on daily life [ 1 ] and has strained the capacity of healthcare institutions [ 2 , 3 , 4 ]. The pandemic continues to have a major impact on daily conduct in our attempt to prevent the spread of the causative agent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus is the third coronavirus known to cause severe disease in humans, and its emergence follows two global outbreaks by SARS in 2002–2003 and the Middle East respiratory syndrome-related coronavirus in 2012 (reviewed in [ 5 ]). To resolve the current pandemic, governments worldwide have variably implemented a series of non-pharmaceutical interventions, from physical distancing, school closures and travel restrictions to better hygiene and face mask requirements [ 6 , 7 ]. Despite ongoing vaccination campaigns, there is a pressing need for new, effective personal protection measures against the infection. Moreover, the emergence and spread of SARS-CoV-2 variants is a major threat to public health. These “Variants of Concern” (VOC) have the potential to evade immunity following vaccination or recovery from infection [ 8 ], and breakthrough cases have been emerging at an increasing rate [ 9 ]. Of the variants, the most concerning in terms of severity of illness is the Delta variant [ 10 ].

SARS-CoV-2 infection is mainly contracted from airborne virions [ 11 , 12 ]. Upon inhalation, the virions bind to cells that express angiotensin-converting enzyme 2 (ACE2), and after host-cell proteases cleave the viral spike protein, the virions enter cells and cause infection [ 13 ]. Therefore, the main site of initial infection is the nasopharyngeal epithelium and, in particular, the ciliated cells, which express high levels of ACE2, and proteases TMPRSS2 and furin on their apical side [ 14 ]. The nose is not only a portal for viral infection but also an important site for viral replication [ 15 ]. Indeed, several studies have described a high viral load in the nasal tract during the first days of SARS-CoV-2 infection [ 14 , 16 , 17 ]. Importantly, since nasal swabs from both symptomatic and asymptomatic patients have been found to contain high viral loads [ 18 , 19 , 20 ], the nose can be considered an important target for both prophylactic and therapeutic interventions against SARS-CoV-2 infection.

An interesting approach to develop simple and safe interventions of this type is based on enhancing the protective function that the nasal barrier already exerts. Indeed, the airway epithelium of the nasal mucosa works as a physical barrier through the production of mucus, which traps pathogens. Thereafter, the clearing action of cilia discharges the mucus into the nasopharynx from where it is eventually swallowed [ 21 ]. A second line of protection is provided by immune cells resident in the nasopharynx-associated lymphoid tissue [ 15 ]. Together, mucociliary clearance and immune responses should protect the nasal epithelium from pathogens, but infection can ensue in cases of high viral exposure or dysfunction of these mucosal defenses.

Several nasal sprays are commercially available for the treatment of respiratory infections such as common cold and influenza (see, for example, Carragelose ® -based nasal spray, Nasaleze ® Cold & Flu blocker, Vicks ® First Defence Cold Virus Blocker), and recent research has investigated the possibility of repurposing these sprays as COVID-19 prophylactic agents. A previous study [ 22 ] observed that two products containing carrageenan, but no pharmaceutically active ingredients, inhibited SARS-CoV-2 infection in in vitro models of air–liquid interface (ALI) cultures of human airway epithelial cells (HAECs) and human lung cells (Calu-3). This same study found that sprays with other inert or active ingredients were cytotoxic. Carrageenans are polyanionic, sulfated polysaccharides from red seaweed; they are widely used in pharmaceutical formulations and have known virus-binding properties [ 23 ]. Other natural substances with broad pharmaceutical applications and virus binding properties are clays, including bentonite [ 24 , 25 , 26 , 27 ]. Bentonite is a clay mineral composed of thin aluminum silicate sheets with a high specific surface with a net negative charge; these properties contribute to its ability to bind viral particles and molecules such as drugs [ 26 ]. We therefore hypothesized that a bentonite-containing nasal spray could protect against SARS-CoV-2 and other airborne pathogens. Bentonite suspensions can have thixotropic properties, that is, they reversibly change from a gel when undisturbed to a fluid colloid when agitated [ 28 ]. We envisioned a bentonite-containing nasal spray that could be applied as a liquid, but in the nasal cavity, it would form a durable, protective gel barrier.

We therefore devised a nasal spray formulation (AM-301) with the aim of providing a safe and effective means of protection against harmful airborne particles. Seeking to minimize potential side effects and to facilitate frequent and compliant use, AM-301 is composed of only inert ingredients such as pharmaceutical excipients and substances that are generally recognized as safe. Because the components are neither metabolized nor absorbed and the mechanism of action is physical, not chemical, AM-301 is a non-pharmaceutical medical device from a regulatory perspective. This study tests the ability of AM-301 to prevent SARS-CoV-2 infection or mitigate existing infections in vitro using a model of primary human nasal airway epithelium (MucilAir, Epithelix, Geneva, Switzerland).

2.1. In Vitro Safety

Inserts of a 3D model of the primary human nasal airway epithelium (MucilAir) were repeatedly exposed to AM-301 or its matrix (lacking bentonite), or left untreated for 4 days, and then tested in four standard assays to evaluate MucilAir integrity. TEER measurements ( Figure 1 A) at baseline were in the normal range (200–600 Ω cm 2 ) for all inserts, indicating their suitability for use in toxicology testing. Mean values for inserts treated with AM-301 or the matrix and for untreated inserts increased slightly over 4 days. These results indicate that the product did not have any adverse effects on tissue integrity (2-way repeated measures ANOVA: treatment, F (2,6) = 29.30, p = 0.0008; time, F (2.112, 12.67) = 153.0, p < 0.0001; interaction F (8,24) = 15.76, p < 0.0001. Post hoc Tukey’s test: Day −3: untreated vs. matrix, p > 0.05; untreated vs. AM-301, p > 0.05; matrix vs. AM-301, p > 0.05; Day 1: untreated vs. matrix, p > 0.05; untreated vs. AM-301, p = 0.0143; matrix vs. AM-301, p = 0.0264; Day 2: untreated vs. matrix, p = 0.0057, untreated vs. AM-301, p > 0.05, matrix vs. AM-301, p = 0.0005; Day 3: untreated vs. matrix, p > 0.05, untreated vs. AM-301, p = 0.0049, matrix vs. AM-301, p = 0.0210; Day 4, untreated vs. matrix, p = 0.0476; untreated vs. AM-301, p = 0.0082, matrix vs. AM-301, p > 0.05).

In vitro safety of AM-301 on MucilAir inserts (human nasal airway epitheliums). ( A ) Transepithelial resistance (TEER) over 4 days of exposure to AM-301 or its matrix lacking bentonite. ( B ) Lactate dehydrogenase (LDH) release assay for cytotoxicity. Data are expressed as a percentage of the amount of LDH released by lysed cells. ( C ) Ciliary beat frequency after 4 days of exposure to AM-301 or its matrix.

The release of LDH to the basolateral medium, a sign of cell lysis, was assayed after 2 and 4 days of exposure to the products ( Figure 1 B). At both time points, the normalized percentage of cytotoxicity was well below 5% for treated and untreated inserts alike (unpaired t -test, matrix vs. AM-301: Day 2 ( p = 0.776); Day 4 ( p = 0.392). These results indicate that the product had no acute cytotoxic effects on cells and that, in all treatment conditions, only normal cell turnover occurred (values ≤ 5%). After 4 days, cilia beating frequency at the apical surface was measured ( Figure 1 C). Untreated inserts had a mean frequency of 4.6 Hz, while inserts treated with the matrix or AM-301 had slightly lower values (3.5 and 3.7 Hz; unpaired t -test, p = 0.011 and p = 0.025, respectively).

2.2. In Vitro Efficacy

2.2.1. pre-viral load (prophylactic) efficacy.

To test AM-301′s ability to protect against SARS-CoV-2 infection of the nasal epithelium, MucilAir inserts were treated apically with the product, its matrix, or physiological saline shortly before exposure to the virus (wild-type or Delta variant). The application of the product was repeated daily for 4 days ( Figure 2 A,B). In case of infection by the wild-type (WT) variant, viral replication was robust in both saline- and matrix-treated inserts, with more than 10-fold daily increases in titer from Days 1 to 3 and a smaller increase on Day 4. In contrast, in AM-301-treated inserts, viral replication was strongly dampened. On Day 4, a 2-log reduction in TCID 50 compared with saline control was observed, which corresponds to about a 99% lower viral titer ( Figure 2 A).

AM-301 as prophylaxis (pre-viral load application) against SARS-CoV-2 infection. MucilAir inserts were treated for 10 min with physiological saline, AM-301, or its matrix, followed by viral suspension for 3 h. Then, inserts were washed and incubated for up to 4 days with daily reapplication of saline, matrix, and AM-301. ( A ) Bar chart with mean values (bars) and individual data points (void circles) of inserts infected by SARS-CoV-2 WT (independent replicates, n = 3 per group). ( B ) Bar chart with mean values (bars) and individual data points (void circles) of inserts infected with SARS-CoV-2 Delta variant (independent replicates, n = 5 per group). ( C , D ) Linear mixed-effects model. The log-linear scatter plot shows individual log-transformed data and regression lines for negative control samples (saline- and matrix-treated inserts; dashed line) and for AM-301-treated inserts (continuous line). Black bullets represent the AM-301+virus group, the white squares represent the matrix+virus group, and the white triangles represent the saline + virus group. The viral growth kinetics in saline and matrix-treated groups (controls) were not significantly different from each other.

AM-301 was shown to be effective also when inserts were infected with the SARS-CoV-2 Delta variant, with a six-fold reduction in viral titer compared with saline and matrix-treated groups on Day 3, and of six- and three-folds on Day 4, respectively ( Figure 2 B).

Viral titer for the inserts not exposed to SARS-CoV-2 was below detection, indicating that the test substances and culture medium were free of viral contamination (data not shown for the sake of clearness in the graphical representation).

Because viral replication was unhindered in the matrix-treated samples, we can infer that bentonite within the AM-301 formulation is primarily responsible for the effect.

The data from the above prophylaxis experiments (pre-viral load application of AM-301) were statistically analyzed using a linear mixed-effect model ( Figure 2 C,D). The time profile of SARS-CoV-2 infection in inserts that received a prophylactic treatment with AM-301 was significantly decelerated compared with that of inserts that received saline or matrix, both when the infection was caused by the WT and by the Delta variants ( Figure 2 C,D, respectively). In case of the WT variant, the saline and matrix experimental conditions showed significantly faster viral titer growth compared with the one observed in AM-301-treated inserts (t = 5.13; p < 0.001). AM-301 was able to significantly decelerate viral titer growth also in case of infection by the Delta variant, compared with inserts receiving saline solution or the matrix ( Figure 2 D, t = 4.69, p < 0.001).

2.2.2. Post-Viral Load (Mitigation) Efficacy

To test AM-301’s ability to mitigate an existing SARS-CoV-2 infection of the nasal epithelium, MucilAir inserts were infected and then treated with test substances starting 24 h after infection ( Figure 3 A,B). A high viral titer was observed in saline- and matrix-treated samples, while the AM-301-treated inserts showed a lower viral titer, both in case of infection by SARS-CoV-2 WT and by the Delta variant ( Figure 3 A,B). In case of infection by SARS-CoV-2 WT, at the end of the treatment period (Day 4), inserts that had received AM-301 showed significantly lower viral titer (12- or 8-fold lower, respectively) than saline- or matrix-treated inserts ( Figure 3 A).

AM-301 as mitigation (post-viral load application) of SARS-CoV-2 infection. Test substances were applied 24 h after the start of the experiment. ( A ) Bar charts with mean values and individual data points of inserts infected by SARS-CoV-2 WT (independent replicates, n = 3 per group). ( B ) Bar chart with mean values and individual data points of inserts infected by SARS-CoV-2 Delta variant (independent replicates, n = 5 per group) ( C , D ) Linear mixed-effects model. The log-linear scatter plot shows individual log-transformed data and concave curves for negative control samples (saline- and matrix-treated inserts; dashed curve) and for AM-301-treated inserts (continuous curve). The model shows a deceleration in exponential growth, as is typically observed for sigmoidal behaviors.

AM-301 was effective at reducing the viral titer also in the case of infection by the SARS-CoV-2 Delta variant ( Figure 3 B), reaching a maximum effect on Days 3 and 4. Indeed, on Day 3, viral titer measured in inserts treated with AM-301 was 6.6-fold lower and 7.3-fold lower than the one measured in inserts receiving saline solution or matrix, respectively. On Day 4, a more moderate reduction was observed, reaching 3.1- and 3.3-fold reductions compared with the saline- and matrix-treated groups, respectively.

The viral titer for the inserts not exposed to SARS-CoV-2 was below detection, indicating that the test substances and culture medium were free of viral contamination (data not shown).

As in the prophylaxis experiment (pre-viral load application), data from the mitigation arm of the study (post-viral load application) were also analyzed with a linear mixed-effect model ( Figure 3 C,D), which revealed that (i) the time profile (replication kinetics) of SARS-CoV-2 titer was not impacted by matrix or saline solution; (ii) the time profile of SARS-CoV-2 titer in the presence of AM-301 was significantly decelerated (SARS-CoV-2 WT, t-value 2.50, p < 0.05; Delta variant, t-value 4.08, p < 0.001) compared with inserts that received saline solution or matrix. Importantly, all experimental conditions were statistically equivalent at baseline. All data were considered valid, and no outliers were excluded.

Altogether, despite noticeable intragroup variability, these results suggest that AM-301 can mitigate an established infection even when applied several hours post-exposure to the virus, both in the cases of the SARS-CoV-2 WT and the Delta variant.

3. Discussion

To study the ability of AM-301 to prevent or reduce SARS-CoV-2 infection in the nasal mucosa, we used a well-established model of primary human nasal epithelium also for viral infections, including SARS-CoV-2: MucilAir [ 29 , 30 , 31 , 32 ]. AM-301 was studied to determine its safety in MucilAir, its efficacy in preventing MucilAir from being infected by SARS-CoV-2, and its ability to mitigate an established infection in MucilAir without any previous treatment.

In the first part of the study, we performed in vitro safety assays (TEER, LDH, and CBF) to assess potential toxicity issues of AM-301. The results displayed in Figure 1 A–C show that AM-301 and its matrix (lacking bentonite) had no toxic effects on MucilAir inserts despite repeated application over 4 days: the measures of tight junction integrity in treated cultures did not differ from those of untreated cultures, and an LDH assay of cytotoxicity revealed no increase in cell death. A slight reduction in ciliary beating frequency (CBF) was detected in AM-301 and the matrix-treated inserts compared with the controls ( Figure 1 C). However, there was no difference between AM-301 and its matrix, suggesting that bentonite is not responsible for this effect, which may rather be due to the viscosity of the formulation. Importantly, safety and tolerability of AM-301 were further confirmed in a clinical investigation with 36 allergic rhinitis patients, where AM-301 was well tolerated and was considered safe for human use [ 33 ].

In the second part of the study, we focused on the evaluation of AM-301 as a potential prophylaxis or treatment against SARS-CoV-2 infection. To investigate that, we used the same in vitro model of human nasal airway epithelium (MucilAir), receiving AM-301 application either pre-viral load ( Figure 2 , to simulate a prophylactic use) or post-viral load ( Figure 3 , to simulate a mitigation use post-exposure). The efficacy of AM-301 was tested both against the SARS-CoV-2 WT and the SARS-CoV-2 Delta variant. Because of technical reasons (i.e., availability of the SARS-CoV-2 Delta variant), the infection with SARS-CoV-2 Delta variant occurred at MOI 0.1, 5-fold lower than the one used for the SARS-CoV-2 WT (MOI = 0.5). This detail must be taken into account when comparing the viral load throughout the experiment ( Figure 2 A,C vs. Figure 2 B,D and Figure 3 A,C vs. Figure 3 B,D).

The results shown in Figure 2 indicate that pre-viral load application of AM-301 (but not of its matrix) on MucilAir inserts was protective against SARS-CoV-2 WT infection, as just a daily application of the product led to a 2-log (99%) reduction in viral titer by Day 4 ( Figure 2 A). AM-301 was shown to be able to also protect against infection by the SARS-CoV-2 Delta variant. Indeed, the viral titer measured in inserts receiving AM-301 was six-fold lower than the one for saline- or matrix-treated inserts already on Day 3, and six- and three-folds lower (respectively) at the end of the experiment ( Figure 2 B). In order to specifically evaluate the effect of AM-301 on the kinetics of the viral titer growth, we used the linear mixed-effects model [ 34 , 35 ], which showed a significant deceleration in viral titer growth for both the SARS-CoV-2 WT and Delta variants ( Figure 2 C,D, respectively). Importantly, AM-301 also showed efficacy in reducing viral titer load ( Figure 3 A,B) and in decelerating viral titer growth ( Figure 3 C,D) when the infection had already occurred ( Figure 3 , post-viral load application). Indeed, on Day 4, inserts that received AM-301 application 24 h post-infection showed a 12- or 8-fold reduction in the viral titer compared with the saline- and matrix-treated inserts, respectively, when the infection was elicited by the SARS-CoV-2 WT and and 3.1 and 3.3-fold reductions, respectively, when the infection was elicited by the SARS-CoV-2 Delta variant ( Figure 3 A,B).

The effects exerted by AM-301 can be attributed to a mechanical, not biological, action. Indeed, AM-301 was developed to mechanically prevent the virus from contacting the nasal mucosa and infecting the upper respiratory airways and to trap or bind it for clearance by mucociliary clearance, ultimately helping to prevent a dramatic viral replication and spread in the airways. This proposed mechanism is based on the hypothesis that viral particles are bound by the complex gel mesh of AM-301 stabilized by bentonite particles and not exclusively due to the presence of polyanionic substances [ 36 , 37 , 38 ]. The advantage of this type of non-pharmacological principle is that, potentially, AM-301 may have a broad spectrum of action on viruses and allergens, which can be trapped as soon as they enter the body by passing through the nose.

AM-301 is a substance-based medical device that contains only excipients and inert ingredients generally recognized as safe. Clays such as bentonite, a key component of the formulation, can also be used to detoxify water of fluoride or heavy metals [ 26 ], and bentonite is the basis of an oral treatment for acute infectious diarrhea (diosmectite, Smecta [ 39 ]). Its virus-binding properties have been known for many years [ 25 , 40 , 41 , 42 ], but to our knowledge, this is its first application used to protect against airborne viruses. Concerns on the possibility of AM-301 reaching the lungs are substantiated by reports of lung toxicity induced by clays such as bentonite [ 43 , 44 ]. AM-301 application via a nasal spray was therefore designed to ensure that the deposition of AM-301 is exclusively local, in the nasal cavity. The spray’s droplet size distribution was tuned to be well above the threshold of 10 μm to minimize particle deposition in the lungs [ 45 ]. AM-301 formulation characterization, nasal deposition pattern, and nasal residence time data are the objectives of a separate study (manuscript in preparation).

Bentonite in synergy with other formulation components confers thixotropic properties to AM-301, permitting its easy application with a nasal spray pump, which results in a protective film once it contacts the nasal epithelium. The lack of preservatives, decongestants, and other pharmacologically active molecules was intended to ensure maximal safety and, potentially, compatibility with the nasal microbiome. Further investigations to confirm this would be of particular interest. Indeed, this feature may be particularly important, since a reduction or imbalance, most recently observed also for SARS-CoV-2, in nasal microbiota diversity provoked by influenza seem to be associated with pathological conditions of the respiratory tract, such as chronic rhinosinusitis, asthma, bronchiolitis, allergic rhinitis, and otitis media [ 46 , 47 ]. Therefore, these features of AM-301 suggest that its use is unlikely to alter the nasal microbiome, maintaining the physiological integrity of the nasal epithelial barrier [ 48 ].

Conducting this study was challenged by several factors that may account for the noticeable intragroup variability: differences in the mucus quantities produced by the MucilAir inserts and technical difficulties in the washing procedures to evenly remove the mucus from all inserts. However, these in vitro results highlight the potential and relevance of AM-301, since the MucilAir tissue model can be considered a worst-case scenario in terms of protection from a viral infection compared with the in vivo situation. Indeed, MucilAir lacks a supportive immune system to protect against infection, and mucociliary clearance of viral particles does not occur. AM-301 was applied once every 24 h, whereas in patients, 2–3 administrations per day would be likely. Indeed, clinical data from an allergen exposure chamber study showed that AM-301 well tolerated and provided a protective effect lasting more than 3 h [ 33 ]. The encouraging results of these studies in which the effect of AM-301 was shown for both viruses and allergens imply a mechanism of action likely to be applicable to diverse airborne particles and call for further investigations in vivo and in humans, to further evaluate AM-301 as a medical device with a broad spectrum of action against as other viruses, allergens, and possibly pollutants.

Intriguingly, since nasal sprays such as AM-301 are not absorbed by the nasal mucosa and are discharged from the nose to the pharynx (manuscript in preparation), AM-301 may also exert its beneficial virus blocking effects in the throat. Since the oral cavity is the main production site of aerosols and airborne droplets [ 49 , 50 ], this action might decrease the potential for viral transmission to other people by talking or coughing 51 . The effect of AM-301 on viral load is currently under clinical investigation.

Currently, the entire world must deal with the health, social and economic damage that the COVID-19 pandemic caused. Several therapies and vaccines have been developed, allowing us to gradually return to normal life. The ability of SARS-CoV-2 to mutate quickly and the high cost of medications, vaccines, and protective measures as well as supply chain challenges make this process even more difficult in developing countries [ 52 , 53 ]. It is thus critical to have efficacious strategies that can contrast viral spread rapidly and that are helpful in contrasting different viral strains. Furthermore, its stability at high temperature, tested and confirmed in accordance with relevant guidelines (manuscript in preparation), allows for its use in warm climates. This preliminary study suggests that AM-301 could be a safe, non-pharmacological, easy-to-use nasal spray that could reduce the risk of infection from SARS-CoV-2 and potentially from other airborne viruses by acting as an “intranasal mask”. It appears to be a promising strategy for self-protection against airborne viruses and as a complement to existing preventive measures such as increased hygiene, physical distancing, and vaccination.

4. Materials and Methods

4.1. virus and cell cultures.

The SARS-CoV-2 strain 2019-nCOV/Italy-INMI1 was obtained from the National Institute for Infectious Diseases Lazzaro Spallanzani IRCCS (Rome, Italy) [ 54 ]. The SARS-CoV-2 strain hCoV-19/USA/PHC658/2021 (Lineage B.1.617.2; Delta Variant) was obtained from Bei Resources. The virus was propagated on VERO cells, collected, aliquoted, and stored at −70 °C until use at Texcell (Evry, France). For viral titration assays, VERO cells were cultured in DMEM supplemented with 4% fetal bovine serum (FBS). The cell line had been obtained by Texcell from the Pasteur Institute (Paris, France). Testing for mycoplasma contamination using the MycoTOOL Mycoplasma Real-Time PCR Kit (Roche Diagnostics GmbH, Mannheim, Germany) was negative.

MucilAir Pool tissue cultures were obtained from Epithelix (Geneva, Switzerland) [ 54 , 55 , 56 ]. MucilAir Pool consists of human airway epithelial cells collected from 14 healthy adult donors (male and female) and reconstituted as a 3D tissue in a two-chamber system; for this study, only nasal epithelial cells were used. The cells were cultured at 37 °C (humidified 5% CO 2 atmosphere) on Costar Transwell porous inserts (0.33 cm 2 each, 24-well plates) with MucilAir serum-free culture medium (cat. no. EP04MM, Epithelix). Approximately one month after seeding, when the cultures were fully differentiated and pseudo-stratified, with basal cells, ciliated cells, and mucus cells, they were exposed to air on the apical surface and were considered suitable for experimental use. Prior to testing, MucilAir Pool cultures (hereafter “MucilAir inserts”) were cultured with 0.7 mL culture medium in the basolateral chamber and air at the apical surface; the medium was changed every 3 days. Each insert had approximately 500,000 cells.

4.2. Nasal Spray Formulation

The nasal spray formulation tested (AM-301) in this study is a medical device containing bentonite (magnesium aluminum silicate) in a matrix composed of mono-, di- and triglycerides; propylene glycol; xanthan gum; mannitol; disodium EDTA; citric; acid and water. All components are listed in the Inactive Ingredient Database of the US Food and Drug Administration (FDA), are classified as “generally recognized as safe”, or are approved for use as food additives by the FDA. The formulation is a white to light beige, aqueous gel emulsion with a pH of 6.0. AM-301 is odorless and tasteless. When we applied it to our own nasal mucosa or palmar skin, it had a soothing non-irritant, lotion-like consistency.

Before testing, AM-301 and its matrix were brought to room temperature and vigorously agitated for 10 s. The amount of product tested on MucilAir inserts was calculated to roughly correspond to the amount that would be delivered to the nostril by a standard, commercial spray applicator (140 µL per actuation). Considering that the total adult nasal cavity surface area is 160 cm 2 [ 57 ] and that a nasal spray coats the anterior third of the cavity [ 21 ], 5.3 μL of product should be tested per square centimeter of tissue. Since MucilAir inserts are 0.33 cm 2 , 10 μL of a 1:5 aqueous dilution of AM-301 or its matrix (diluted in water immediately before use) was tested per insert.

4.3. Safety Assay Design

AM-301 was tested for potential cytotoxic effects in a series of assays to determine the viability and function of the epithelial tissues used routinely for assessing the quality of MucilAir preparations. These assays, performed by Epithelix, included an assay for transepithelial electric resistance (TEER), which measures tight junction integrity [ 58 ]; an assay for lactate dehydrogenase (LDH) release into the basolateral medium, a standard measure of cytotoxicity; and an assay for cilia beating frequency (CBF), which is an index of the main function of airway cells, namely mucociliary clearance [ 59 ]. The three assays were conducted simultaneously on one set of 12 MucilAir inserts over a 4-day protocol with repeated apical application of the product, as described below and illustrated in Figure 4 A (see “Safety assays” below for the individual methods).

Schematics of experimental protocols. ( A ) Safety assay experimental design. CBF, cilia beating frequency; LDH, lactate dehydrogenase; TEER, transepithelial electric resistance. ( B ) Efficacy assay: Pre-viral load application (Prophylaxis). ( C ) Efficacy assay: Post-viral load application (Mitigation).

Briefly, 3 days before use, the inserts were washed apically with 200 μL culture medium (10 min), and TEER was measured to verify their integrity. The apical medium was discarded, and the inserts were returned to the incubator for 3 days. On the first day of product testing (Day 0), the inserts were transferred to new 24-well plate with 500 μL/well fresh medium. The apical surface was treated in triplicate with 10 μL of a 1:5 aqueous dilution of AM-301 or its matrix or left untreated. The inserts were returned to the incubator for 24 h.

On Day 1, 200 μL of the medium was applied apically for TEER measurements. The apical medium was removed, and the inserts were transferred to a new 24-well plate with 500 μL/well fresh medium. The inserts were treated as on Day 0 and returned to the incubator. On Day 2, 200 μL of the medium was applied apically for TEER measurements. The apical medium was removed, and the basolateral medium was collected for LDH assays. The inserts were transferred to a new 24-well plate with 500 μL/well fresh medium, treated as on Day 0, and returned to the incubator. On Day 3, 200 μL of the medium was applied apically for TEER measurements. The apical medium was removed, and the inserts were transferred to new 24-well plate with 500 μL/well fresh medium; the inserts were treated as on Day 0 and returned to the incubator. On Day 4, cilia beating on the apical surface was observed and its frequency was quantified. Then, 200 μL medium was applied apically for TEER measurements. Finally, the basolateral medium was collected and assayed for LDH.

4.3.1. Transepithelial Electric Resistance (TEER) Assay

Transepithelial electric resistance (TEER) was measured with an EVOMX epithelial volt-ohm meter (World Precision Instruments). Briefly, 200 μL of the MucilAir culture medium (34 °C) was applied to the apical surface of each MucilAir insert. The electrodes were washed with 70% ethanol and then with medium prior to insertion into the apical and basolateral media. Resistance values (Ω) were measured at room temperature; they were corrected and converted to TEER (Ω cm 2 ) using the following formula:

where 100 Ω is the resistance of the membrane and 0.33 cm 2 is the surface area of the insert. The assay was performed in triplicate. Normal values for MucilAir are in the range 200–600 Ω cm 2 [ 54 ].

4.3.2. Lactate Dehydrogenase (LDH) Assay

Lactate dehydrogenase activity in the basolateral medium was assayed using the Cytotoxicity Detection Kit (cat. no. 4744934001, Roche Diagnostics GmbH, Mannheim, Germany,). For the high control, MucilAir inserts ( n = 3) were treated apically with 100 μL of a lysis solution for 24 h in a tissue culture incubator, and the basolateral medium was collected. For the assay, 100 μL of the medium from each test sample and from the high controls was transferred to a 96-well plate; culture medium alone was used as the low control ( n = 3). The reaction solution was added (100 μL/well), and the plate was incubated for 15 min in the dark at room temperature. Then, a stop solution was added (50 μL/well), and absorbance was read at 490 nm on a plate reader. Cytotoxicity was expressed as a normalized percentage relative to the high and low controls. Normal values for MucilAir inserts are ≤5%, which corresponds to a physiological turnover of cells in culture [ 54 ].

4.3.3. Cilia Beating Frequency (CBF) Assay

Cilia beating frequency at the apical surface of MucilAir inserts was observed at room temperature under a Primovert inverted microscope (Zeiss, Jena, Germany) with a 10× objective. A Mako G-030B machine vision camera (Allied Vision Technologies, Stadtroda, Germany) mounted on the microscope was used to capture 256 movies (125 frames per second). The registrations were analyzed with Cilia-X software (Epithelix), which calculated the cilia beating frequency. Normal values of frequency for MucilAir are in the range of 4–8 Hz.

4.4. Efficacy Assays Design

AM-301 was subjected to a series of in vitro efficacy assays using MucilAir inserts at Texcell. The ability to prevent SARS-CoV-2 infection was tested in a prophylaxis assay, while the ability to reduce SARS-CoV-2 replication in already-infected tissues was tested after post-exposure treatment in a mitigation assay. For both assays, inserts were treated apically with 100 μL of a suspension of SARS-CoV-2 in a culture medium at a multiplicity of infection (MOI) of 0.5 for the WT strain and 0.1 for the Delta variant.

4.4.1. Pre-Viral Load Protocol

In the pre-viral load assay (prophylaxis), MucilAir inserts were apically treated with test items for 10 min before exposure to SARS-CoV-2 (SARS-CoV2 WT: MOI = 0.5; SARS-CoV-2 Delta variant: MOI = 0.1), and viral replication was measured over 4 days with daily apical treatments with the saline solution, the matrix, or AM-301. In the experiment evaluating the ability of AM-301 to prevent SARS-CoV-2 WT infection ( Figure 2 A,C), TCID50 measurements were performed on three independent replicates per group. In the experiment evaluating the ability of AM-301 to prevent a SARS-CoV2 Delta variant infection, TCID50 measurements were performed on five independent replicates per group ( Figure 2 B,D).

Briefly, on Day 0, the inserts were transferred to a new 24-well plate with 500 μL/well fresh medium and washed apically by incubation with 200 μL medium for 20 min at 34 °C in a humidified 5% CO 2 atmosphere; then, the apical medium was removed. The apical surface was then treated with 10 μL of a 1:5 aqueous dilution of AM-301 or of its matrix, or with 10 μL saline diluted 1:10 in water. After 10 min, without washing, the apical side was treated with 100 μL SARS-CoV-2 suspension (SARS-CoV-2 WT: MOI = 0.5; Delta variant: MOI = 0.1). Infection was allowed to proceed for 3 h in a 34 °C incubator and stopped by gentle washing of the apical surface with 200 μL medium (3 times). Viral replication was assessed immediately and daily over 4 days as follows:

• (1) Viral sampling : 300 μL of the medium was applied to the apical surface. After 20 min at 34 °C, the conditioned apical medium was collected and stored at −70 °C until analysis.
• (2) Medium change : Inserts were transferred to a new 24-well plate with 500 μL/well fresh medium. The conditioned basolateral medium was collected and stored at −70 °C for possible future analyses.
• (3) Repeat treatment : The apical surface was treated with a product or left untreated, as described above, and the inserts were returned to the 34 °C incubator.

Treatments were repeated daily, and sampling was performed only on Day 4.

4.4.2. Post-Viral Load Protocol

In the post-viral load assay (mitigation), MucilAir inserts were apically infected with the SARS-CoV-2 WT or Delta variant, and viral replication was measured over 4 days with daily apical treatments of physiological saline, AM-301, or its matrix In the experiment evaluating the ability of AM-301 to mitigate SARS-CoV-2 WT infection ( Figure 3 A,C), TCID50 measurements were performed on three independent replicates per group. In the experiment evaluating the ability of AM-301 to prevent SARS-CoV2 Delta variant infection, TCID50 measurements were performed on five independent replicates per group ( Figure 3 B,D).

Briefly, on Day 0, the inserts were transferred to new 24-well plates with 500 μL/well fresh medium and washed apically by incubation with 200 μL medium for 20 min at 34 °C in a humidified 5% CO 2 atmosphere; then, the apical medium was discarded. The apical surface was infected with 100 μL of SARS-CoV-2 suspension (SARS-CoV-2 WT: MOI = 0.5; Delta variant: MOI = 0.1); viral suspension was added to 12 inserts per protocol, while 3 inserts served as negative viral controls. Infection was allowed to proceed for 3 h in a 34 °C incubator and stopped by gentle washing of the apical surface with 200 μL medium (three times). Viral replication was assessed immediately by the addition of 300 μL of the medium to the apical surface and incubation for 20 min at 34 °C; the conditioned apical medium (Day 0) was collected and stored at −70 °C until analysis. The inserts were transferred to new 24-well plates with 500 μL/well of fresh medium and returned to the incubator.

On Day 1, viral replication was assessed as on Day 0 for all inserts. All inserts were transferred to new 24-well plates with 500 μL/well of fresh medium. Inserts belonging to the mitigation arm of the study were treated with AM-301, its matrix, or physiological saline and returned to the incubator.

On Days 2 and 3, viral replication was assessed in all inserts; the conditioned medium (Days 2 and 3) was collected and stored at −70 °C. Inserts were transferred to new 24-well plates with fresh medium; treated with AM-301, its matrix, or saline; and returned to the incubator. On Day 4, viral replication was assessed in all inserts.

4.5. Viral Titer Assay

The viral titers were determined in the conditioned medium collected from the apical side of MucilAir inserts. The samples were prediluted 1:32 in DMEM containing 0.5 mg/mL gentamicin (to avoid any possible interference of the test products on cell growth). Then, using one 96-well plate per sample, serial three-fold dilutions were made in the same culture medium with eight replicates per dilution (10 dilutions per sample); eight wells received fresh medium (negative controls). A fixed volume (50 μL) from each well was transferred to sample titration plate, and 50 μL VERO cell suspension (10 5 cells/mL in DMEM plus 4% FBS) was added per well. Plates were incubated at 37 °C in a 5% CO 2 humidified atmosphere for 6 days. Then, a 0.2% crystal violet solution was added to stain DNA in live, adherent cells. The tissue culture infectious dose that killed 50% of cells (TCID 50 ) was calculated using the Spearman–Kärber method.

4.6. Statistical Analyses

Data from the LDH and CBF analyses were compared using the unpaired t -test. The results from the TEER analyses were compared using two-way repeated measure ANOVA followed by post hoc Tukey’s test. The level of significance was set at p < 0.05. The results from the SARS-CoV-2 prophylaxis and mitigation experiments were analyzed using linear mixed-effect models with log-transformed data [ 35 ]. The minimal adequate mixed-effect model was achieved by top-down selection, adjusting for multiple comparisons. Analyses were performed using the lme4 package [ 34 ] as implemented in the programming language R [ 60 ].

Acknowledgments

Valerie Matarese provided writing and editing services on early versions of this manuscript.

Author Contributions

F.F.: conceptualization of the work, revision of important intellectual content, final approval, and agreement to be accountable for all aspects of the work; R.J. and V.F.: draft of the work, interpretation of the data, final approval, and agreement to be accountable for all aspects of the work; S.M., M.G. and C.V.: acquisition and analysis of the data, draft of the work, final approval, and agreement to be accountable for all aspects of the work; M.B.: statistical analysis and interpretation of the data, draft of the work, final approval, and agreement to be accountable for all aspects of the work; S.C. and I.P.H.: substantial contribution in the draft of the work, final approval, and agreement to be accountable for all aspects of the work. All authors have read and agreed to the published version of the manuscript.

The study was planned, funded, and overseen by Altamira Medica (Zug, Switzerland).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Data availability statement, conflicts of interest.

F.F., R.J., V.F. and I.P.H. are employees of Altamira Medica. MB is a consultant for Altamira Medica. S.M., M.G., and C.V. are employees of Texcell (Evry, France). S.C. is CEO of Epithelix (Geneva, Switzerland).

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