FDA Approval refers to the list of drugs approved by the Food and Drug Administration (FDA) for sale in the United States. New drugs receive extensive scrutiny before FDA approval in a process called a New Drug Application or NDA. After approval of an NDA, the sponsor must review and report to the FDA every patient adverse drug experience of which it learns. Unexpected serious and fatal adverse drug events must be reported within 15 days; other events on a quarterly basis. As a condition of approval, a sponsor may be required to conduct additional clinical trials, called Phase IV trials.