ANIMAL TESTING

Once a potential drug has been identified, animal testing is usually the first step, typically in two or more species, since drug effects vary across species. Many of these studies are ADME (absorption, distribution, metabolism and excretion) and toxicity studies. They document absorption of the drug, how the body breaks it down chemically, the toxicity and activity of the breakdown products (called metabolites), and the speed at which the drug and its metabolites are cleared from the body.