EDIT: I don't mean that this isn't already approved for human use. But there's a whole list [0] of existing drugs being tested, and a lot of them are effective in vitro.
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?
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 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
https://www.forbes.com/sites/victoriaforster/2020/03/03/ther...
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.
Unless it's a wonder drug like penicillin was in the 1940s, you need a trial to test whether it works.