Urine drug testing is frequently performed by immunoassay (IA) due to ease of use, rapid turn-around time and the ability to screen multiple drug classes. However, IA drug screens have limited sensitivity and specificity due in part to capture antibody cross-reactivity with structurally similar interfering compounds, producing false-positive results. Specifically, amphetamine (AMP) IAs demonstrate broad antibody cross-reactivity with non-targeted compounds that are structurally or physically related to phenethylamines.

Cross-reactivity of antibodies