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The potential of Ambroxol in the prevention and treatment of COVID-19

Cipher

Administrator
Messages
838
A short introduction to Ambroxol:

Ambroxol is indicated as "secretolytic therapy in bronchopulmonary diseases associated with abnormal mucus secretion and impaired mucus transport. It promotes mucus clearance, facilitates expectoration and eases productive cough, allowing patients to breathe freely and deeply" [1] Ambroxol is also used as a local analgesic for sore throat in the form of lozenges. It's available OTC in most parts of the world, but doesn't seem to be available in the US. It has been in medical use since 1979. Normal daily dosages tend to range from 30mg to 75mg.

A short introduction to how SARS-CoV-2 infects cells:

It has been reported that the SARS-CoV-2 uses a receptor called ACE2 to enter cells. In order to use the ACE2 receptor, the virus needs to be primed by something called a protease. [2] [3] One prominent protease is called TMPRSS2.[4] An in vitro study (meaning in a test tube) showed that a TMPRSS2 inhibitor called Camostat (an approved drug in Japan used for chronic pancreatitis and postoperative reflux esophagitis) blocked the virus from entering cells. [2] Many influenza viruses also use TMPRSS2 to enter cells. [4] However, there are various other endogenous airway proteases that can prime both SARS-CoV-1 [5] (very similar to SARS-CoV-2, most likely translatable) and various influenza viruses.

How Ambroxol might prevent/treat COVID-19

Ambroxol have been shown to up-regulate the levels of the endogenous protease inhibitors that the body produce. [6] Ambroxol's up-regulation of these defensive molecules have been shown to increase the survivability of mice exposed to lethal levels of influenza virus. [6] [7] The daily dosage found to be most effective (higher dosage being less effective) was 10mg/kg, which for humans would be equivalent to 0,8 mg/kg[8], meaning 64mg ambroxol for someone who weighs 80kg. It have also been shown to inhibit rhinovirus infection (common cold) in cultures of human tracheal epithelial cells by various mechanisms. [9] One of these mechanisms (reducing acidic endosomes) might have effects against SARS-CoV-2: "We observed potent inhibition of SARS-CoV S-mediated transduction by two different classes of lysosomotropic agents in multiple cell lines, strongly suggesting that SARS-CoV glycoprotein requires acidification of endosomes for entry." [10]

"Ambroxol is a lysosomotropic drug of clinical use to treat conditions of productive cough for its mucolytic action. Ambroxol triggers the exocytosis of lysosomes via neutralization of lysosomal pH and calcium release from acidic calcium stores. Presumably for this reason, Ambroxol was also found to improve cellular function in some disease of lysosomal origin such as Parkinson's or lysosomal storage disease."[11]

In 2006, a Japanese study looked at the effect of ambroxol vs 2 other drugs regarding the incidence of upper respiratory tract infection (URTI) during 1 year (41 subjects in total). The ambroxol group had 66% less URTIs compared to one drug and 73% less URTIs compared to the other drug. [12]

Ambroxol may be an ACE2 binding agent according to an artificial intelligence drug target screening done by researchers at the School of Basic Medicine Sciences at Peking University. [13] [14] [15] This has not been tested in vitro to my knowledge.

Chinese hospitals are already using ambroxol in the treatment of moderate and severe COVID-19 patients, according the "Handbook of COVID-19 Prevention and Treatment", produced by the First Affiliated Hospital, Zhejiang University School of Medicine. The dosage is 30 mg x 2 (60mg total)/day i.v, equivalent to 76mg oral immediate release ambroxol / day [16].

According to a newly released paper by researches from IBM, computer simulations indicate that ambroxol (among ∼20 other compounds) may inhibit SARS-CoV-2’s main protease. "Currently, it is well known that the SARS-CoV-2’s main protease (Mpro) constitutes one of the most attractive antiviral drug targets, because the viral maturation almost exclusively relies on the Mpro’s activity." [17]

And now, the most interesting paper to date; ambroxol was one of 90 compounds found to inhibit SARS-CoV-2 replication in an in vitro screening of 1,520 approved drugs, according to a pre-print paper released 7 days ago. [18] The concentration used to test the drugs was 10µM.
10µM = 0,00001 molar. Ambroxol hydrochloride's molar mass is 414.56 g/mol [19].
414.56 * 0,00001=0,0041456 g/L ambroxol.
0,0041456 g/L = 4145,6 ng/ml ambroxol.

What's the concentration of ambroxol in lung tissues at normal dosages? According to one paper[20], the concentration of ambroxol in the bronchoalveolar lavage fluid was 135ng/ml after 2 weeks of 60mg ambroxol x 2 (120mg/day). They also state that a dilution factor of 50 can be applied to estimate tissue distribution. That would mean 135*50=6750ng/ml ambroxol in the lung tissue after 120mg ambroxol/day. Another study referenced in the same paper stated that ambroxol concentrate in pulmonary tissue (aka the lungs) at levels up to 20 times that in blood (plasma according to other papers referring to the same study [21]). The maximum plasma level after ingesting 1 x 30 mg immediate release ambroxol is reported to be around 60 ng/ml [22]. That would extrapolate to 60*20=1200ng/ml ambroxol in lung tissue after ingesting 30mg ambroxol.

This indicates that ambroxol may have antiviral effects against SARS-CoV-2 at concentrations achievable with normal dosages.

There seems to be an epidemiologic study underway in China evaluating ambroxol's potential in the treatment of COVID-19, sponsered by Boehringer Ingelheim, one of the world's largest pharmaceutical companies. [23]

Ambroxol have also been shown to have a wide range of anti-inflammatory properties [24] [25], and to reduce elastase release by human neutrophils by 40% at 10µM [26], the same concentration used in the SARS-CoV-2 in vitro study above. "Elastase breaks down elastin, an elastic fibre that, together with collagen, determines the mechanical properties of connective tissue." [27] Ambroxol have also been shown in mice to improve neuronal survival and reduces white matter damage through suppressing endoplasmic reticulum stress in microglia after intracerebral hemorrhage. [28]

Ambroxol can be bought OTC from German pharmacies, you can find some here. Many pharmacies do not send to addresses outside of Germany, but some do. One such pharmacy is www.bodfeld-apotheke.de.
 
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Hip

Senior Member
Messages
17,824
Thanks for posting this detailed analysis, Cipher.

And now, the most interesting paper to date; ambroxol was one of 90 compounds found to inhibit SARS-CoV-2 replication in an in vitro screening of 1,520 approved drugs, according to a pre-print paper released 7 days ago. [18] The concentration used to test the drugs was 10µM.

Looking at table 1 in that study [18], they do not seem to provide the EC50 value for ambroxol. Usually in antiviral studies, they will determine the EC50 concentration in μM or μg/ml. The EC50 is the concentration of the antiviral substance which reduces viral replication by 50% in vitro. So the EC50 is standard measure of antiviral potency.

Typically to have a reasonable antiviral effect in vivo, you would want to achieve at least 5 times the EC50 concentration in the bloodstream. Potent commercial antivirals may achieve around 50 times the EC50 in the blood.

But I can't see any EC50 value for ambroxol in that paper.

I am not sure if you can use the 10 μM ambroxol concentration they stated, as we do not know what degree of antiviral effect that the 10 μM concentration achieved.


(I spent many months reading antiviral studies, looking for possible off-label antiviral substances for coxsackievirus B, so learnt a bit about these studies).
 

Hip

Senior Member
Messages
17,824
Keep looking for other useful coronavirus antivirals, @Cipher!

The info you found on povidone-iodine gargling for coronavirus was great. Myself and elderly family members are now using 0.5% povidone-iodine nasal spray and as well as mouthwash/gargle after each time there is a risk of exposure (by being in proximity to someone). I only use povidone-iodine when there is a potential exposure to coronavirus, though.

I also take echinacea and allicin after any significant potential coronavirus exposure, as together these should reduce the risk of infection by a factor of 4 — see this post. Again I only use this if there is a potential exposure to coronavirus, so it's quite economical on tablets.



Azithromycin in your study looks interesting. That's been used already to treat COVID-19, along with hydroxychloroquine.

Looking at table 1 of the study, azithromycin has a nice low EC50 of 2.12 μM. The molecular weight of azithromycin is 749 g/mole, so we can calculate that this EC50 is 1.6 μg/ml.


This pharmacokinetic study found azithromycin 1000 mg once daily for 3 days in humans resulted in a peak concentration (Cmax) of 18.6 mg/kg in the lung tissue, which is the same as 18.6 μg/ml.


One important thing that must be taken into consideration in these pharmacokinetic calculations is the plasma protein binding of the drug or supplement. Plasma protein binding is the percentage of the substance which binds to proteins in the blood. When you ingest any substance, a certain percentage of it will bind to blood proteins, and the rest will remain free, being dissolved in the blood plasma.

The free drug principle states that it is only the free portion of the substance which has an active biological effect in the body; the portion of the substance bound to proteins becomes inactive, and has no effect.

So looking up the plasma protein binding of azithromycin, this study says it is 50%.

I think the lung Cmax concentration of 18.6 μg/ml represents the sum of the free and protein-bound portions of azithromycin. So the concentration of the free azithromycin in the lungs will be half that figure, that is 9.3 μg/ml.



This 9.3 μg/ml of free azithromycin in the lungs looks good, because the EC50 is 1.6 μg/ml, and so this concentration is 9.3 / 1.6 ≈ 6 times higher than the EC50. That looks like relatively mild but possibly useful antiviral effect.
 
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pattismith

Senior Member
Messages
3,931
This small study from France though reports no benefits from the azithromycin + hydroxychloroquine combination on 11 COVID-19 patients.
I would like to know how long the disease started before they started the treatment.
Raoult tested and treated 1061 patients (published some days ago) in the early days of infection, and found a mortality rate of 0.5%: Not sure if it is meaningful though...

https://forums.phoenixrising.me/thr...ovid-19-coronavirus.79447/page-4#post-2268763
 

pattismith

Senior Member
Messages
3,931
@Hip, this is a french article about 3 family doctors treating their patients with azithromycin + Effizinc (2/day) +Singulair with some successes:

Dr Gastaldi already treated 200 patients (starting as soon as possible, not testing because tests were not available), and got 0 deaths, only two went serious and went to hospital and came back OK.
 

Cipher

Administrator
Messages
838
I am not sure if you can use the 10 μM ambroxol concentration they stated, as we do not know what degree of antiviral effect that the 10 μM concentration achieved.

Thanks for pointing that out, hopefully they will analyze the EC50 soon!

The info you found on povidone-iodine gargling for coronavirus was great. Myself and elderly family members are now using 0.5% povidone-iodine nasal spray and as well as mouthwash/gargle after each time there is a risk of exposure (by being in proximity to someone). I only use povidone-iodine when there is a potential exposure to coronavirus, though.

I use it myself daily as a mouthwash, not only as preventive measure for COVID-19, but also for gum health. I recently had a nasty gum infection, and after using povidon-iodine mouthwash I got it under control and it haven't reoccurred. It stains calculus, but not the actual teeth (as of yet). It seems to have many properties that make it very interesting in the context of periodontitis as it inhibits MMPs[1], penetrate biofilms[2], have anti-inflammatory properties[2] and doesn't induce bacterial resistance[2].
 
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frozenborderline

Senior Member
Messages
4,405
Weirdly I have a bit of chest congestion which I guess is probably not covid since that's a dry cough

But either way where can I get ambroxol. Two birds one stone. @Hip do u know a source?