How is a new medicine tested?

How is a new medicine tested?

It is legally prohibited to test any new medicine directly on humans because the possible side effects of the medicine can be life-threatening. Therefore, new medicines are first tested on cells in the laboratory. If the medicine meets experts’ expectations in these experiments, it is then tested on animals. Only if these tests yield good results is the medicine allowed to be tested on humans.

If a medicine is to be tested on animals, ideal animals are those that are mammals—meaning their bodily systems closely resemble the human body (all mammals fulfill this condition). It should be easy to keep these animals in laboratories. The animals should be small, so that large laboratories are not required. Within a few years of research, multiple generations of the animals can be studied for the possible effects of the medicine (i.e., the animal should be able to reproduce soon after birth). It should be easy to make genetic changes in the animal. They should be easy to handle (such as administering the medicine or taking tissue samples), and the cost of obtaining, feeding, and maintaining them should be low.

All these conditions are fulfilled by mice. Among all mammals, mice are the easiest to keep in laboratories. They reproduce quickly, can be kept in small cages, are very easy to handle, and the cost of keeping them is very low. That’s why the infrastructure to supply mice to scientific laboratories exists in every developed country—companies exist whose job is to provide scientists with mice according to their specifications. Scientists can even order mice with the exact genetic mutations they require.