Is there NO way to stop COVID-19?

UK trials have begun of a nasal spray that could prevent COVID-19 infections

A few weeks ago, it was announced that UK trials were beginning of a nasal spray proven to kill 99.9% of the coronavirus that causes COVID-19. The idea, broadly, is that you’d use the spray first thing in the morning, during the day after social interactions, and then again in the evening — and it would prevent the virus from taking hold and making you ill.

Awesome, right? Simple, cheap, portable. Sort of like cleaning your teeth regularly: prevention rather than cure. Combined with a vaccine, particularly for anyone at high risk such as those in healthcare settings, it could put a stop to the whole thing — and might also turn out to be effective on other, less deadly but still annoying, viruses.

But, I hear you ask, what is it? Because if I’m going to squirt something up my nose several times a day, I have questions…

Nitric oxide has the chemical formula NO

Fair enough. It’s actually, mostly, nitric oxide, which has the chemical formula NO.

Yes, there are plenty of wordplay options here. The researchers have already jammed the letters NO into their company name, and done the acronym thing, to get SaNOtize Nitric Oxide Nasal Spray (NONS). If the trials are successful, it’s probably only a matter of time before we get: “Say NO to coronavirus!” marketing. (Any ad agencies reading this, I’m claiming copyright.)

But that aside, unless you’re a chemist you might be thinking about some half-remembered chemical names and frowning at this point. Isn’t that… used in rocket fuel? Or… wait… isn’t that… the nasty smoggy stuff that causes lung problems?

Ah, well, there are several nitrogen oxides. Let me summarise:

Nitric oxides in the atmosphere cause photochemical smog.

There are other nitrogen oxides, not to mention ions — but let’s not spend all day on this. Nitrogen forms this confusing hodgepodge of oxides because it has five electrons in its outermost shell (it’s in group 15 of the periodic table) and because there’s not much difference in the electronegativities of oxygen and nitrogen. So essentially, it can share electrons with oxygen to form bonds in a number of different ways to obtain a stable, full outer shell.

For any students reading this, I’m sorry. You… pretty much just have to remember these. Yes, I know. That’s why experienced chemists so often use the shorthand NOx — we just can’t be bothered keeping all the names straight. (Okay, before someone shouts at me, actually NOx is handy because we’re often talking about more than one oxide at a time, and it allows us to easily express that.)

Back to NO. It’s a colourless gas, and it has an unpaired electron, which makes it a free radical. And… here we go again. Aren’t we supposed to eat lots of antioxidant-rich fruit and vegetables to mop up free radicals? They’re bad, aren’t they?

Viagra (Sildenafil) makes use of the nitric oxide pathway which causes blood vessels to dilate…

Yes and no. Free radicals are reactive species which damage cells and can cause illness and ageing. Too much exposure to free radicals causes something oxidative stress, which is definitely bad. But. It turns out that nitrogen oxide is an important signalling molecule, that is, a molecule which is the body uses to send chemical signals from one place to another. In particular, nitrogen oxide “tells” the smooth muscle around blood vessels to relax, causing those blood vessels to dilate, and increasing blood flow. Viagra (aka Sildenafil) uses the nitric oxide pathway, and I think we all know what that does, don’t we? Good.

Nitric oxide has also been shown to reduce blood pressure, which is generally considered a good thing — up to a point, obviously. This is why you can buy lots of so-called nitric oxide supplements, which, since nitrogen oxide is a gas at room temperature, don’t actually contain nitric oxide on its own. Rather, they’re a mixture of amino acids and other things that supposedly help the body to make NO. But it might be cheaper, and healthier, to eat plenty of beetroot or drink beetroot juice, since there’s evidence that does the same sort of thing.

As always, the dose makes the poison. Too much nitric oxide is definitely problematic, but administered in the right way and in appropriate doses, it’s extremely safe.

It’s suggested that the nitric oxide in the SaNOtize nasal spray destroys the virus and also helps to stop viral replication within cells. Plus, it blocks the receptors that the virus uses to enter cells in the first place. Essentially, it locks the doors and rains down fire on the potential intruders — nice work.

You only need to use the spray occasionally, because developing a COVID-19 infection isn’t instant. First the virus gets into your nose, then it attaches to cells, then it replicates, and then it sheds into your lungs. There are timescales involved here — so long as the spray is used every so often it should do the trick.

Another advantage is that this should, theoretically, work on other strains — where the current vaccines may not. So it could provide a very important stopgap when vaccination isn’t immediately available.

This is only in the early stages of clinical trials so, for now, wear your mask.

All sounds fabulous, doesn’t it? It might be, but, we’re in the early stages with this. Clinical trials have now started in the UK, are already in Phase II in Canada and have been approved to start in the USA. Researchers are hopeful, but we need to wait for the evidence.

So in the meantime, wear a mask, wash your hands, and take a vaccine if you’re offered one. Stay safe out there!


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The cold cure that’s 5000 years old

Could we just remove the front of my face? I think it'd be less painful....

Could we just remove the front of my face? I think it’d be less painful….

A couple of days ago I was struck down with a sinus infection. This is something I thought I’d had before, but it turns out that what I’d actually had before was an uncomfortably stuffy nose. Whereas this, on the other hand, was the sensation that someone had put my forehead in a vice and was inflating my eyeballs with a bicycle pump.

I explained this to the doctor. He nodded sympathetically and suggested a drug that’s been used, in one form or another, for five thousand years.

If you’re new to this blog, you might be wondering at this point whether, when I say ‘doctor’ I actually mean ‘naturopath’ (or some other thing that translates as ‘not a doctor’). But, no, this was a properly qualified member of the medical profession. Well, I hope he is. I mean, I haven’t looked him up on the General Medical Council’s list. I assume my surgery did that. I’m sure they did. Anyway….

207px-(+)-Pseudoephedrin

Pseudoephedrine

What was this mysterious, ancient medicine? It was pseudoephedrine, otherwise known (in the UK anyway) by the brand name Sudafed®.

It’s a drug many of us have probably taken to help with cold symptoms, and not given much thought to, but it’s actually got a pretty interesting story.

Pseudoephedrine falls under the class of amphetamines. The ‘amine’ bit of that word refers to the NH group (or it might be NH2, or even just N) and, being one of the fundamental bits in proteins, it turns up in lots of biologically active molecules. It’s in paracetamol (acetaminophen) for example, and antihistamine drugs used to treat allergies, as well as many molecules that occur naturally in the body, such as dopamine and adrenaline (epinephrine).

It’s also there in methamphetamine (commonly known as ‘crystal meth’ or just ‘meth’). In fact, pseudoephedrine and methamphetamine are chemically similar, and the latter can be synthesised from the former (I’m not recommending any of my readers try this; it’s very much frowned upon from a legal point of view). For this reason, the sale of pseudoephedrine is tightly regulated; in the UK you can only buy it over the counter in a licensed pharmacy, and then only in small blister packs. (Cold medications that you can pick up from the shelf usually contain the far less effective phenylephrine.)

800px-Ephedra_sinica_alexlomas

The Ephedra sinica plant

Where does it come from? These days, pseudoephedrine is made in a three-step process, the first of which involves yeast fermentation, but it was first isolated from plants, in particular Ephedra sinica, also known as Chinese ephedra or Ma Huang.

This is where the five thousand years comes in, because these plants have been used in Chinese medicine for millennia. In fact, Ephedra is one of the oldest known medicines. It’s described in the legendary Chinese pharmacopoeia Pen-tsao Kang-mu, and became a common part of Chinese prescriptions to treat cold symptoms, fevers and asthma.

The first substance in Ephedra plants to be used in western medicine was Ephedrine. It was isolated in 1885 by a Japanese chemist called Nagai Nagayoshi, but it was then rather forgotten about until 1920s, when it was rediscovered and became a popular treatment for asthma.

In those days, steroid inhalers had yet to be developed, and the standard treatment for asthma was adrenaline. This was problematic, because adrenaline isn’t orally stable: it had to be injected. Ephedrine, by contrast, would work if swallowed as a pill, making it much easier to use.

Ephedrine_enantiomers

Ephedrine is made up of a mixture of these two mirror-image molecules

Unfortunately, ephedrine had rather unpleasant side-effects. It caused raised blood pressure, and then there were a number of other potential problems such as dizziness, trembling, headache, irregular heartbeat and even, in some cases, heart attack and stroke. Worth the risk perhaps, if you’re in the middle of a life-threatening asthma attack, but not something you’d want to use routinely.

The story goes (although I haven’t been able to verify this by finding, say, a recorded study) that when the use of the whole Ephedra plant as a treatment was compared to the use of pure ephedrine, people noticed that the side-effects were much less severe, even though the whole plant still appeared to be an effective treatment. This caused researchers to wonder whether there was some other substance in Ephedra that had subtly different effects on the body.

Whether this observation was really made or not, it turned out there was another active molecule in the Ephedra plant. It was first separated from ephedrine in in 1927, and was given the name pseudoephedrine, literally ‘false ephedrine’. Ephedrine and pseudoephedrine are structural isomers: they have the same number and type of atoms, ordered slightly differently. This is a common theme in medicinal chemistry: switching just a couple of atoms around can make big differences to the way the human body reacts to drugs.

Like ephedrine, pseudoephedrine was an effective bronchodilator and vasoconstrictor (causing blood vessels to shrink), but its effects were less dramatic, which made it a lot safer. It doesn’t raise blood pressure nearly as much, and is far less likely to cause something really nasty like a heart attack. That said, it’s not side-effect free, and it should go without saying that anyone with an existing medical condition should speak to their doctor before using it. Likewise, don’t go messing about with Ephedra plants.

Vasoconstriction is why pseudoephedrine such a good decongestant. Less fluid leaves the shrunken blood vessels and therefore less fluid enters the throat, nose and sinus linings. This reduces inflammation mucus production, and the incessant pounding of a sinus headache eases up a bit.

Of course, pseudoephedrine doesn’t somehow know to restrict itself to your nose and lungs. Blood vessels throughout the body are affected. This can be useful – for example, pseudoephedrine can help to treat ear infections – but it can also result in other, less desirable effects. In particular, pseudoephedrine suppresses breast-milk production, and for this reason shouldn’t be used by new mothers trying to establish breastfeeding. It might also interfere with mucus membranes in the vagina, potentially causing a small reduction in fertility and, not surprisingly, a substance which is a vasoconstrictor can also aggravate erectile dysfunction. Basically, if you’re trying to make a baby this might be one to avoid, although if you’re stuffed up with a cold you might not feel like it anyway, so perhaps it doesn’t matter.

Anyway, I know what you’re all desperately wondering: But, Chronicle Flask, did it sort out your sinus infection?!

dara

“Science knows it doesn’t know everything; otherwise, it’d stop.”

Well, actually, I’m relieved to report that after taking three doses of pseudoephedrine twice a day for a couple of days the pain has eased up considerably. Of course, there’s nothing antiviral (or antibacterial) in this medicine, but it would appear that my immune system managed to take care of the infection for me, once the inflammation was reduced and the excess fluid which was causing the pressure was able to (yuck) drain away.

To quote the comedian Dara O’Briain:
“‘Oh, herbal medicine’s been around for thousands of years!’ Indeed it has, and then we tested it all, and the stuff that worked became ‘medicine’.”


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