There are 3 stages of animal testing, in each they test effectiveness and Grinch I used to smile and then I worked at Tesco shirt. You have a phase 1 trial, which tests safety on 10-100 people, then you have phase 2 on people which tests effectiveness and follows up on safety. Last but not least you have a phase 3 trial that tests effectiveness, safety and a few other things just on a large scale of about anywhere from 1000 to 60 000 people. After that you have a approved drug.