Question: how do you inverstigate medicine so that it can treat diffrent people of all diffrent illnesses and nationalites and most importantly their ages ...???

Lilian Hunt answered on 10 Mar 2014:

When you make medicine, you’re often making it to treat one specific thing, like a cough, so a lot of the time you can focus on just treating that. As people are surprisingly similar even if they are different ages and nationalities, it will work for nearly everyone.

Then you have medicine that needs to treat many different illnesses. This involves understanding what it is about these illnesses that is actually the same. For example, someone could have arthritis and be in pain from that and someone else could have injured their leg muscle playing sport. Both these people can take ibuprofen – a pain killer. That’s because we investigate how ibuprofen works and know that both these people have pain caused by inflammation or swelling and ibuprofen helps stop that and therefore stop the pain. So for this we needed to have investigated exactly how the medicine works in the body.

For treating people with different ages, a lot can depend on the size of the person. You might have seen on some medicines that it says children under 12 should take less than an adult. That’s because children’s bodies are basically the same as an adults but much smaller, so they need less medicine. With older people, their bodies are often not as good at breaking down the drugs in the medicine so for that reason they may need to take less of the the medicine as well.

Really the key to all of this is investigating and understanding the pathways in the body the medicine affects and we can test this in the lab on cells and some animals. We then work out how much is needed by testing really small amounts on healthy adults and work from there.