Screening for drugs of abuse with the Roche ONTRAK assays

A family of manual, qualitative, latex agglutination inhibition immunoassay screening tests (ONTRAK, Roche) for amphetamines, barbiturates, cocaine, marijuana, morphine, and phencyclidine were evaluated. The assays are inexpensive, rapid, portable, and easy to perform, requiring little training to obtain proficiency. The tests are sensitive to drug concentrations at or around the stated cutoff values. The ONTRAK results agree well with the results obtained from fluorescence polarization immunoassay (FPIA) or radioimmunoassay (RIA) screening and GC/MS confirmation. Potential drawbacks of the test kits include the subjective nature of the qualitative assays and the lack of a positive control. The ONTRAK system provides a reasonable means of conducting field testing for drugs of abuse.