Drug Screening (DS) is used in the ER for pre-employment testing and identifies the most commonly abused substances, such as cocaine, opiates, tranquillizers, sedatives-barbiturates, and hallucinogens. It is a method for determining the presence of one or more drugs of abuse, usually in urine, by "stat" methods, such as EMIT (enzyme-mediated immunologic technique), FPIA (fluorescence polarisation immunoassay). The first step in the procedure is to identify a condition or a therapeutic field with an unmet need. A "druggable" target is identified, and drug screening then begins. Molecules that can interact with the target and/or support the intended phenotypic response are found during drug screening.