Common Causes of False Positive and False Negative Results in Amphetamine Screening Tests

Abstract: The need for toxicological screening of amphetamine users is growing in parallel with its increasing abuse. At the same time, it turns out that these substances most often give false results in rapid drug immunoassay. Therefore, the aim of the present work was to investigate the sources of false positive or false negative results. For this purpose, an analysis of the literature sources in the databases of Google Scholar, PubMed, and Science Direct, was made. The results showed that a number of prescription or OTC medications can cause false positive results due to cross-reactivity (ephedrine, pseudoephedrine, labetalol, metoprolol, some antidepressants, metformin, ranitidine, ofloxacin, selegiline, etc.). In this regard, alternative medications for patients who often have to undergo such screening have been proposed. Some possibilities of unintentionally or intentionally inducing false negative results have also been highlighted. Popular approaches to fooling the screening test are diluting the urine, adding adulterants (marketed products or homemade chemicals), and providing foreign or synthetic urine. Summarizing the possible sources of errors in drug screening is expected to objectify the interpretation of the obtained results.