The DRI® Methadone Assay is intended for the qualitative and semi-quantitative determination of methadone in human urine.
The DRI Methadone Assay is a homogeneous enzyme immunoassay using ready-to-use liquid reagents. The assay uses specific antibodies, which can detect methadone in urine. The assay is based on the competition of an enzyme glucose-6-phosphate dehydrogenase (G6PDH) labeled drug and the drug from the urine sample for a fixed amount of specific antibody binding sites. In the absence of drug from the sample, the specific antibody binds to the drug labeled with G6PDH and the enzyme activity is inhibited. This phenomenon creates a direct relationship between the drug concentration in the urine and the enzyme activity. The enzyme G6PDH activity is determined spectrophotometrically at 340 nm by measuring its ability to convert nicotinamide adenine dinucleotide (NAD) to NADH.