An experimental drug is a substance that has been tested in a laboratory and has got approval from regulatory authorities to be tested on people. In the United States, the body responsible for approval is the U.S. Food and Drug Administration (FDA). A drug may be approved for use in one disease or condition but be considered experimental or investigational in other diseases or conditions.
The United States Food and Drug Administration’s Investigational New Drug (IND) program is the means by which a pharmaceutical company obtains permission to ship an experimental drug across state lines (usually to clinical investigators) before a marketing application for the drug has been approved. The FDA reviews the IND application for safety to assure that research subjects will not be subjected to unreasonable risk. If the application is cleared, the candidate drug usually enters a Phase 1 clinical trial.