Immunoassay Techniques Used in Drug Test Screening: Cloned Enzyme Donor Immunoassay (CEDIA)

This version of the course is no longer available.
Need multiple seats for your university or lab? Get a quote
The page below is a sample from the LabCE course . Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about (online CE course)
Immunoassay Techniques Used in Drug Test Screening: Cloned Enzyme Donor Immunoassay (CEDIA)

The cloned enzyme donor immunoassay (CEDIA) refers to an immunoassay which uses a genetically-modified β-galactosidase enzyme. This enzyme has two units; an enzyme acceptor and an enzyme donor. These units alone are inactive, but in solution, they become activated and reassemble. As a single unit, they can react with the substrate and produce a change in absorbance. In the CEDIA, reagent antibodies keep the enzyme subunits apart, by physically blocking binding of the monomer subunits from forming a tetramer. If there is drug present in a patient sample it will bind to the antibody and 'overwhelm' it, allowing the monomers to bind and enzyme activity to ensue. See figure below for a depiction on the assay's mechanism of action.