At some point, yes. But that's not the first place they're tested. The first place their tested could simply be a petri dish, as penicillin was. Then it goes up

At some point, yes. But that's not the first place they're tested. The first place their tested could simply be a petri dish, as penicillin was. Then it goes up the ranks into mammals more and more similar to us - rats, pigs, monkeys, etc. Usually it's not every step, because there really isn't a big reason to and that can slow development and increase costs of life-saving drugs.