Development of assays for drugs of abuse

The treatment and prevention of drug abuse has required the development of assays for biological markers to assess an individual's adherence to a treatment regimen or to the prescribed abstinence of drug use. Generally, this requires assays sensitive enough to detect a few nanograms of a particular metabolite per milliliter of urine. Most frequently, the identify of the drug or combination of drugs is not known. This placed a large responsibility on the development of reliable methods. To accomplish this mission, the National Institute on Drug Abuse funded a multiyear, multiple-contract program. This program included the synthesis of reference drugs, their metabolites, and labeled derivatives; the development of several new analytical methods, especially using gas chromatography/mass spectrometry and immunoassay techniques; the establishment of analytical service facilities; animal and human pharmacokinetic studies; and laboratory proficiency testing. Many of the assays are now commercially available and widely used. Assay development requires the consideration of a number of factors, namely, specificity, sensitivity, time, simplicity, and cost. These factors are illustrated in a number of examples.