Before a drug can be bought or perscribed, it must go through heavy testing to make sure it is safe and that it actually works. There are many stages to this, listed below. Grab a pen and make notes, or print this off and highlight key points - it may help you to remember it.
Computer models are the first thing that a possible new drug is tested on. The model simulates a human's response, suggesting how the human body might react to it. This is not as acurate as trying it on a live animal, but it puts a stop to the risk of harming one unecessarily. If the drug passes this test, then it goes on to step 2.
The drug is then tested on human tissues. This shows the effect on human cells, but it still doesn't show us…