Question: if you animal test, how do you know the reaction on the aninal will be the same on the human?

Jo Sadler answered on 11 Mar 2015:

Hi Megan. This is a great question and one that there isn’t a complete answer for. In the first instance, we normally assume that there effect on an animal will be simlar to humans. Depending on what part of the body we are trying to target, we can pick an animal which has more simliar proteins (proteins are the most common targets for drugs) to try and make it into a better model.
However, at the end of the day, after testing it on animals, we do test new drugs on humans. To start with, we test them on healthy volunteers (to check there are no really bad side effects) and then we test it on people who actually have the disease it is for, to check that it works.

By comparing the results of the animal to human tests we can learn more about the differences between the two, and feed that knowledge back into future studies.

Hope that helps!