Do they just put random chemicals in people and see what happens?
In: Biology
Random plants. So perhaps eating poppies was good for headaches, or willow bark. Then we figured out which specific chemical in those plants was doing the trick (opium and aspirin) and refined them out.
Or perhaps we figure out that a toxic creature kills by causing endless bleeding and that gives us a blood thinner.
Now we have enough computing power to design a custom molecule from scratch with confidence of it’s effects.
Scientific method! Often the result of research supports or forms a theory about what causes a given disease. Then scientists do an experiment. e.g. get two groups of volunteer patients, and given their doctors either the test medicine or a placebo (fake medicine, often just a bland sugar pill). The patients and the doctors don’t know who received what, but the trial organizers do, so they can compare results between the trial medicine and the control group with minimal complicating factors.
Maybe the trial medicine patients have better outcomes than the control group. Maybe they have worse outcomes. Maybe there’s no difference at all. Maybe it’s both at the same time, e.g. headaches go away but their fingernails become wrinkly. This all provides more data to inform future theories.
Often past research supports affecting certain mechanisms or biological targets. So if we know XYZ affects a certain receptor, they can design a molecule similar to XYZ to hopefully bind more or less strongly to said receptor. But you still need to test it because biology is complicated and that might not be the only way things interact with the new molecule. But medicine doesn’t always know exactly WHY something works. Sometimes it just does, but regardless of HOW it works, the scientific method can give strong evidence whether or not it *does* work.
It can get complicated, some thing are toxic in high doses and ineffective at low doses, so determining a treatment that actually works can be difficult. But with time and effort often comes progress.
For drugs that were developed before a century ago, people figured it out by observation and experimenting. This resulted in some drugs that were used quite dangerously (laudnum given to babies), some that were effective and reasonably safe (willow bark tea), and some that were mostly placebo effect (taking the medicine made people feel better because they expected to feel better rather than because the medicine does anything in the body). There are still a wide range of traditional and herbal medicines that are in use today.
For drugs that are developed according to modern standards, there is a long process.
Step one: identifying possible medicines.
You can do this by asking traditional healers what they use, by finding new uses for old drugs, by collecting 1000’s random plants or random chemicals and testing if they have any desirable effects on cells in a petri dish, by using a computer program to design a drug, or by using living cells (or living animals) to make a protein that may act as a drug.
Step two: Test the drug in the lab. Use animals that are engineered to get sick with the disease you want to cure. For example you could give mice cancer. Then test to see if your drug cures them. Test lots of different doses and lots of slight variations on your drug until (hopefully) you find something that works. Determine whether the drug is toxic to the mice. Most drugs are toxic at high doses. Hopefully your drug is effective and not too toxic. Final tests usually involve giving the drug to monkeys to test how toxic it is.
Step three: convince a government that this drug is likely to be safe and effective in humans. Get permission to test it in humans.
Now we enter Clinical Trials.
Phase I: Safety test. We ask for volunteers who are willing to be test subjects. Often, if the drug is expected to be potentially dangerous, we ask for terminally ill patients to volunteer. We are literally testing whether the drug kills them faster. We start at very low doses and we take blood tests frequently and we discontinue the trial if we notice evidence that their organs are being poisoned. Hopefully our drug isn’t too toxic.
Phase II: Determining dose and more safety testing. We enroll more patients. We try different doses and schedules. We do blood tests. We monitor their symptoms. We compare how our drug affects people of different sexes and ages and weights. Hopefully we find a drug that is safe and shows some hints of effectiveness.
Phase III: Controlled study. We enroll many thousands of patients in our trial and we randomly assign them to receive either our drug or a comparison drug or a placebo (a pill that contains no drug). We don’t tell individual patients which group they are in. We don’t even tell their doctors which group they are in. They all get pills that look identical. This is called “blinding.” We collect lots of information about how the patients are doing. Usually the people collecting the information aren’t allowed to know who is in what group. The information is passed to the people who will do the math to determine whether our drug is safe and effective compared to both the placebo and the comparison drug. We check to see if there are any dangerous rare side effects. We check to see if there are any subgroups of people who react badly to the drug.
If the Phase III trial shows that the drug is safe and effective and is at least as good as the treatments that were previously available for this illness, then the drug-maker will ask for government approval for the drug. If the government approves it, then doctors can prescribe it with few restrictions. Professional medical societies may even issue proclamations that this new drug is recommended as a standard drug to use.
Doctors can also use drugs “off-label.” If a drug has been shown to be safe and effective for treating one condition, a doctor might experiment with prescribing it for a different condition. Usually this only happens when the patient has a condition that is difficult to treat, and the doctor has run out of other ideas. Sometimes, if a doctor gets good results this way, they will recommend sending that drug straight to Phase III clinical trials to test whether it is good at treating this new condition.
Mostly using random chemicals. A lot of medicines target a particularly shaped receptor or “lock” one way to find a working “key” for that lock is set up a system that tries a whole lot of different chemicals to find if one of them will match.
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