engleski

False-positive methadone urine drug screen in the patient treated with quetiapine

Drug screening through urinalysis is a widely accepted method for rapid detection of potential drug use. The most commonly used tests to screen urine for drugs of abuse are immunoassays, even though false-positive results for drugs of abuse have been reported with a number of these rapidscreening products. Confirmation of presumptive positive urine drug screens, necessary to minimize the reporting of false-positive results, can be costly and time-consuming.We present the case of TM, admitted to the Psychiatry Clinic, Clinical Hospital Centre Split in Croatia, because of the acute psychotic reaction F23. Urine from the patient tested positive for methadone without a history of methadone ingestion. Urine drug screen was performed with the COBAS Integra Methadone II test kit (kinetic interaction of microparticles in solution /KLMS/ methodology) by Roche. Drugs that have been shown to cross-react with methadone feature a tricyclic structure with a sulphur and nitrogen atom in the middle ring, which is common to both quetiapine and methadone. Therefore, it is plausible that this structural similarity between quetiapine and methadone could underline cross-reactivity in the methadone drug screen.Beside quetiapin, a number of routinely prescribed medications have been associated with triggering false-positive urine drug screen results. Verification of the test results with a different screening test or additional analytical tests should be performed to avoid adverse consequences for the patients.

quetiapine ; methadone ; false-positive urine drug screens

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