In the United States, the FDA approves drugs. Before a drug can be prescribed, it must undergo an extensive FDA approval process. This process involves first testing the drug on animals or in medical labs. If found to be safe by the FDA and approved for the next phase of study, the drug is then tested for safety and effectiveness in humans (clinical trials). The drug manufacturer then files a New Drug Application to the FDA, which reviews the application and either approves or rejects it.