Quantitative urine drug monitoring in methadone programs: potential clinical uses

An on-site clinical laboratory in a methadone program can provide semiquantitative urine drug monitoring by using fluorescence polarization immunoassay (FPIA) technology. This report documents a wide range of urine drug levels from threshold to near 2,000,000 ng/ml in this patient population, suggesting how laboratory measures can assist in assessing the severity of addiction. Urine drug level data are reported for drugs of abuse (opioid, amphetamines, cocaine) as well as therapeutic drugs (benzodiazepines and methadone). Clinical uses of quantitation illustrated include screening of all admissions prior to induction on methadone, identification of unusually heavy users, monitoring drug washout, and assessing compliance with prescribed benzodiazepine and methadone regimens. The Clinical Laboratory Improvement Act (CLIA88) has set national certification standards for moderate complexity laboratories using immunoassays and set up a mechanism for monitoring quality in such clinic-based laboratories.