Modified EMIT Dau Immunossay to allow cocaine metabolites determination in urine of crack cocaine smokers - abstract

ABSTRACT

Alkaloidal cocaine (COPC) is widely sold in the West Indies in a form suitable for smoking. These little rocks called "crack", addictive in high doses (typically 120 mg), produce a rapid, intense, high and a very compelling type of COC dependence. The bioavailability and the metabolism of the smoked form (half-life of 56 min versus 78 and 80 min, respectively, after IV and IN COC administration) conduce to low levels of metabolites in serum and in urine. Clinical and forensic toxicology laboratories are more and more solicited for testing major cocaine metabolite benzoylecgonine (BZE). The Enzyme Multiplied Immunossay Technique (EMIT) is a fast, simple and reliable technology. However, the assay cut off concentration for BZE of the commercially available kit (EMIT dau Cocaine Metabolite Immunoassay) is too high (300ng/ml) for serum or urine detectable levels of BZE in cocaine smokers. We proposed a modified EMIT assay to make this technique suitable for level of detection. The immunoassay was applied to ROCHE COBAS MIRA Plus analyser. The increase of the sample volume up to 25 ul and the use of calibration standards 0 to 300 ng/ml conduce to a lower detection limit of 50ng/ml. The within run precision of the assay was less than 10 percent. The results were confirmed by gas chromatography mass spectrometry. The increase of sensitivity was near 30 percent. No false positive results were observed. The presented modification demonstrates the application of currently available EMIT Immunoassay to rapid and reliable testing for BZE in cocaine smokers. (AU)