IMPROVED DETECTION OF COCAINE METABOLITE IN URINE FROM PREGNANT-WOMENAND NEONATES BY MODIFIED IMMUNOASSAYS

The threshold of the Abbott TDx Cocaine Metabolite Assay (TDx) was low ered from 300 ng/mL benzoylecgonine (BE) to 50 ng/mL by dilution of ca librators and controls with drug free urine. The between-run precision of the modified assay was evaluated by analyzing the urine control sa mples containing 50, 100, and 500 ng/mL BE for over a 12-week period w hich yielded CVs of < 8.2%. Five hundred consecutive urine samples fro m pregnant women and neonates tested for BE by EMIT-d.a.u. with the cu t-off value of 300 ng/mL were also tested by the modified TDx assay wi th the new cutoff value of 50 ng/mL. All positive immunoassay results were confirmed by Gas Chromotography/Mass Spectrometry (GC/MS). The mo dified TDx assay resulted in 27 more positive samples than the EMIT-d. a.u. Screening urine samples obtained from the Prenatal Clinic and OB- ER by the modified TDx assay yielded a 70% (51/30) increase in positiv e BE results compared with EMIT-d.a.u. Lowering the threshold of TDx a ssay to 50 ng/mL enhances the detection of BE in this population at hi gh risk for the tragic consequences of cocaine abuse.