Because for a drug to be approved, it has to pass the clinical trial process. If the drug passes this process it can be approved. I would assume that during this process, the fever-reducing and pain-relieving properties showed improvements over placebo. I’d also assume that the rate of side effects was relatively low.
Ultimately it doesn’t matter *how* it works as long as it works and has no super unsafe side effects. The FDA has no requirement that you know how a drug works.
> Paracetamol has a central analgesic effect that is mediated through activation of descending serotonergic pathways. Debate exists about its primary site of action
https://pubmed.ncbi.nlm.nih.gov/18811827/
We do know how it works, there’s just debate over which receptor site in particular it uses. Paracetamol is an old drug that’s been used for decades, we know all the side effects, we know what groups can take it and what groups can’t. If it were invented today would it pass regulators with this discrepancy? Probably but it would be harder and probably more tightly controlled and not sold in most shops. We still don’t know fully how anaesthetics and hypnotic drugs work. We just know that they do.
There is no requirement that we understand how a drug works in order to get approval. The testing that’s required is just for safety and efficacy. There’s no testing required that demonstrates how it works molecularly. There are a number of drugs that probably don’t work via their listed mechanisms at approval: eg, enbrel (actives th17 cells) and Avandia (cdk inhibitor).
For the same a surprising amount of medications are allowed to be sold, despite not knowing the exact mechanism of action; the have demonstrated efficacy, and aren’t harmful enough.
Drugs for depression have poorly understood mechanisms. We still don’t know how or why *ketamine* works, though we have some good ideas (NMDA, it’s thought, and the exact binding site was just recently resolved).
Studies, trials, and history of use. We don’t need to know how a medication works to see benefit from what the medication does, the FDA and FDA like bodies around the world use testing and trials to determine if a medication poses a risk to the general population. We know that in moderate doses it can cause damage to the liver, however due to its wide spread use, high efficacy and low risk of harm it’s deemed effective and safe.
Knowing how a drug works isn’t required for it to be approved/used. We’ve known for a long time that how we first thought SSRIs worked isn’t how they work. We’ve maybe finally, [this year](https://blogs.sciencemag.org/pipeline/archives/2021/02/19/how-antidepressants-work-at-last) got a real answer. [Here’s](https://blogs.sciencemag.org/pipeline/archives/2021/07/15/a-fifty-year-old-cancer-drug-doesnt-do-what-you-think) a 50 year old cancer drug that doesn’t do what people thought it did. (People knew for a while that we didn’t know how it worked, but we didn’t stop using it)
Latest Answers