It seems like the more potent a drug/medication is, the more risks are involved with it, where as drugs with very little risk don’t help nearly as much.
In: Biology
Drugs usually target a certain pathway and receptor in our bodies when we give a drug, we alter or shut that pathway down to get the effect we want. Many pathways do multiple things though. Therefore when you shut down the pathway you get side effects from other things that pathway does. For example ibuprofen (NSAIDs) Block an enzyme called cox1 and cox2. This shuts relieves inflammation and pain but it also inhibits anti-apoptotic signals to gastric mucosa cells which is why once side effect of NSAIDs is stomach ulcers
If a drug had no side-effect, it would have no effect. A drug happens to have certain effect, and when applied to a certain condition one of them is not a side-effect.
If you were to use medication for heart rhythm problems to combat a common cold, a side-effect would be that it affect heart rhythm.
A clear example would be Viagra, which was originally developed for high blood pressure. You can guess what the side effect was.
There were mainly 2 reasons given in this thread and I’ll add a third one:
1) Body has many mechanisms that work on molecular level and most molecules affect multiple systems, or one system’s distruption could affect other systems. (Morphine causing constipation)
2) Too much of a molecule causes too much of an effect (Blood pressure medicine causes very low blood pressure and shock)
3) Balance mechanisms try to balance a drug’s effect when it’s in the body, and when drug is out of the body balance is distupted towards the other way (First you drink too much caffeine to feel over energetic and after a while you drink coffee to feel normal and feel tired more than usual when you don’t drink it)
We don’t know enough about the human body so we are targeting broadly across many areas.
If we target depression we might target serotonin but serotonin modulates a lot of other functions and we don’t know how to target serotonin in just the brain, most serotonin receptors are in the stomach so a common side effect is nausea.
Now we know after 30+ years of targeting serotonin that serotonin might be just modulating something else and that something is what we should be really targeting.
Your brain has hundreds of levers (neurotransmitters) that it uses to tell you what’s going on. When good things happen, it sends moves some levers and you feel good. Drugs work by going in and messing with all the levers, so you feel/think/see things that aren’t appropriate for what is going on around you. This can sometimes damage the levers (or the parts that listen to the status of the lever) because your brain is only supposed to have certain levers on for a certain amount of time.
Damaging those levers (by keeping them on/off too long) can cause long term damage resulting in a world of disorders often including depression and long term paranoia.
The body is a very complicated machine. It is constantly self-adjusting. Drugs are like taking a 9lb hammer and banging on something — it’ll fix that one thing but it throws off other connected things (and things are not always connected in immediately logical ways). The drugs tend not to absorb at a steady rate (taking a pill for example) vs the gradual ebb and flow of bodily functions, so also throws off the machine.
Many systems in the body are regulated with various neurotransmitters, proteins, ions, and the like. They work like glorified keys in locks, where some are master keys that work in many locks, others with very unique keys that only work in one place.
The goal of any pharmaceutical therapy is to find a drug that acts on only the locks that are problematic, while affecting the fewest other systems. Unfortunately as before, there is a tonne of interplay between the systems.
Aspirin (ASA) thins the blood (because [reasons](https://en.wikipedia.org/wiki/Aspirin)). Have a headache or a heart attack? Take Aspirin, ASA thins the blood, allowing it to flow into constricted areas to reduce the pain or help deliver more oxygen. Have a bleeding stroke or bleeding disorder? Take aspirin and the thinner blood will…bleed even more easily. It’s not so much that aspirin is a ‘cure headache key’, it’s a ‘thin the blood’ key (among other effects).
To the original question – why isn’t there a perfect drug for a specific ailment? Because many body systems have overlap between their systems. The same thing regulating your blood pH balance can be responsible for digestive acid production and some other liver function. Affecting any one stage will carry on further down the line. Frankly, the fact that our bodies work at all is nothing short of astounding. Tens of thousands of chemical processes in delicate balance with slight perturbations causing disease and death.
A lot of people are making some very good points but have you ever heard of a PCSK9 inhibitor? They have very few actual side effects. They are tolerated extremely well. They have no real drug interactions that are known. They can reduce your LDL cholesterol from 400+ to 60 nearly instantly. Freaking amazing!
Maybe I missed something in the comments. We may be on the verge of actually discovering something like this. Organic compounds such as cannabis and psilocybin have not been studied as much as others. Benefits do exist, but due to stereotypes and lack of funding, or government regulation, more research must be done.
Consider that a drug is just a chemical compound that is introduced into an extremely complex chemical environment inside your body. It is just not possible to design a chemical compound that will precisely interact with one and only one area inside your body, ignoring everything else (unless we are talking about gene therapy or nanoscale devices – but that’s another story). The drug has to be absorbed somehow and circulated through your system until the active drug molecule finds its match. On top of that, chemicals in our system often share multiple different functions – so either reducing or increasing their levels to treat something is a delicate balance of compromises. Maybe the problem will be temporarily fixed, but at the same time another problem can be generated.
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