Validity testing of commercial urine cocaine metabolite assays: III. Evaluation of an ezyme-linked immunosorbent assay (ELISA) for detection of cocaine and cocaine metabolite

A validity assessment study was performed on the Genetic Diagnostic Enzyme Immunoassay test kit, a new enzyme-linked immunosorbent assay (GDC ELISA) for detection of cocaine and cocaine metabolite in urine. A set of 290 urine specimens, comprised of clinical cocaine urines collected from 5 male subjects who had received single doses of intravenous cocaine, drug-free urines spiked with cocaine, cocaine metabolites, cocaine isomers, and other drug of abuse, were assayed by GDC ELISA. The results were compared with results by gas chromatography/mass spectrometry (GC/MS) assay for benzoylecgonine. Concordance was high between the GDC ELISA assay and GC/MS and with results reported earlier for other commercial assays. Detection times and specificity of the GDC ELISA antibody were most similar to those of the Abuscreen® radioimmunoassay for cocaine metabolite. Overall, the assay produced no false negative or false positive results and appeared to be a reliable screening test for detection of cocaine and benzoylecgonine in human urine.