@BoyWonder, sure. I selected the statin drugs as an example, because they include the most widely prescribed pharmaceutical drug on the planet, Lipitor. If you would like examples from other classes of drugs, please let me know and I would be happy to oblige.
In 2003, an article was published by Nature Reviews describing the history of statin development. I have linked the full text there, but here is a summary:
About 100 years ago, doctors started to think that cholesterol could be linked to heart disease. They observed patients for a while, and became more convinced of this hypothesis. In order to treat heart disease caused by cholesterol, scientists started to look for drugs that could lower cholesterol. They hypothesized that blocking cholesterol synthesis by reducing levels of an important enzyme, 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) would decrease cholesterol, in turn decreasing heart disease.
Chemists were able to synthesize a drug that would do just that. However, doctors did not just test the drug out on any willing person. Instead, the cholesterol-lowering drugs were tested on rabbits, monkeys, and dogs. Only when it was shown to be safe and effective in these animals was the first human trial initiated.
The reason that I offered to provide evidence in any drug class you name is because this is how all drugs are developed. No FDA-approved drug will ever be tested on humans until it has been proven both safe and effective in animals. So, nearly every drug you take, every drug you have taken, and every drug you will take, was shown to be effective in animals before any human was ever prescribed it.