> If it's not in clinical trials yet

Only if its harmful. What if the drug has been in use for other disease with known side effects, will we still wait for clinical trials?

It depends on the risk profile. A loss of hair for a cancer drug won't be a big deal but might be problematic for common cold.

I won't have that side effect anyway

Took me a while, but i see what you did there ;)

Yes, same here - I'm the star of the Bald & Beautiful in my family, but I don't want to influence my receding hair choices to them, unless you plan on landing male role in future Fast & Furious, Die Hard, or any Rock-infused movie.

This is no common cold, specially for people 60+ years old.

Even if it's already approved for human use, we still need to test for efficacy before prescribing it to everyone. See also: remdesivir, favipiravir, Prezcobix, chloroquine and ruxolitinib, among many others.

Why? If side effects are marginal and well understood, just start using it and see how well it does.

What's the functional difference between that and a clinical trial, from the perspective of the patients?

It would be essentially a clinical trial, an open-label one.

There even have been several blinded trials, that were discontinued mid-way, because the drugs being tested were so effective.

To continue giving placebo and denying obvious cure would be unethical, and so the trial was stopped, placebo arm cancelled - and everyone got the actual medicine.

in a trial, you get invited and you might be placeboed out as a control.

in the “just try it and see scenario”, you offer it as a possibility, and everyone who ops in, gets it.

it might not be as scientifically rigorous, but that's a big difference to the patient who suffers from receiving a placebo instead of the real deal

“It does require trials in humans to determine if it’s effective, and I suspect it would also require pre-clinical animal work with SARS-CoV-2 specifically before human trials could start. If it has been shown to be safe for clinical use in other countries, it may be fast-tracked for FDA approval or the FDA may authorize emergency off-label use[with no need for clinical trials],” said Rasmussen, indicating that the FDA will have to examine safety data and pre-clinical data before determining which, if any course of action to take with investigating the drug further.

https://www.forbes.com/sites/victoriaforster/2020/03/03/ther...

It depends whether you want to know if it actually works.

Presumably it's already made it through many stages of clinical trials if we're calling it an existing drug, which means we can skip straight to human trials on infected patients.

You need to take into account dosage.

They usually have to go through it again, FDA clinical trials (phase i, ii, iii) with different dosage to see what's effective. Increase in dosage can increase chances of side effect or create new ones.

There may be laws to get around or fast track that but pharma company have a dedicated department to figure that out. Just like that one company that causes opioid epidemic.

If it's a drug that blocks entry of the virus into human cells, wouldn't it be ineffective on already infected human beings?

If it works it will block infection of new cells. Already infected cells will die and be shed.

Biologists can correct me if I'm wrong, but it seems like fighting infection is a war of attrition. So anything you can do that shifts the balance helps.

Some infections might be a war of attrition, but it's not something you can generalize. Fundamentally, stopping entry would just prevent the virus from infecting more cella in the body (which could worsen symptoms) - and coronavirus is more of your standard fast invasion - burn bright and strong before being eliminated style infection than a chronic slow burn, so stopping that fast invasion could help.

Ianad but presumably when there's a significant risk of crashing the world economy on the other side of the decision, rules on drug safety processes may get changed.

The problem is that unsafe drugs can do way more harm than good and the world economy wouldn't be any better off

https://en.wikipedia.org/wiki/Thalidomide

I don't think the death rate is what would collapse the world economy. Even if the drug ended up killing more people it would still potentially help the economy. Especially if the side effects weren't know for years. Obviously I'm not advocating for this though.

My rule of thumb is to not take anything that’s been on the market for less then ten years. After ten years everyone figures out the real drawbacks and side effects.

thalidomide is still prescribed...

And now that we know it causes birth defects we can tell people about them in advance and control distribution closely...

Not to treat morning sickness in pregnant women!

Clinical trials inform you about both safety and efficacy.

Unless it's a wonder drug like penicillin was in the 1940s, you need a trial to test whether it works.

Almost like how the autoimmune response was the big danger of the Spanish flu, but at a superorganism level

The nature article makes it sound like a lot of the options listed are being tested because there's some evidence of some effectiveness Vs in the story OP posted, it sounds like the mechanism is much better understood.

The Nature article actually mentions the drug in question - camostat mesylate - as one of the TMPRSS2 inhibitors under investigation. (And given how often "this should work, for sure!" drug trials fail to pan out, I'm not sure that "this works in theory, here's why" is that good of an indicator)