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Possible reasons for the occurrence of false-negative results in urine drug screening

Stanila Stoeva


Introduction: Immunoassay screening of urine samples play a central role in the monitoring and fight against ever-increasing drug abuse. Thus, the aim of the present work was to clarify the reasons for deliberately or unintentionally causing of false-negative screening results.

Materials and Methods: For the purpose of the study, an analysis of Google Scholar, PubMed, and Science Direct databases was conducted.

Results:  The exact number of false-negative results in the analytical practice cannot be precisely determined because of the impossible confirmation of each screening test. In this regard, the screening of drug abuse appears to be a huge challenge these days due to multiple reasons. On the one hand, it is necessary to take into account the physicochemical properties of sometimes an unknown analyte, as well as the physiological characteristics of each individual. On the other hand, the test antibodies available to date do not have the necessary specificity for absolutely all drugs, especially designer ones. At the same time, there is an unlimited access to information and products supporting the manipulation of urine samples, respectively the achievement of false-negative results. In response, analytical chemistry offers a variety of methods to address the problem of filtering out abusers.

Conclusion: Because of their high throughput and low cost, immunoassay techniques continue to be a cornerstone of drug screening, whether for clinical or criminological purposes. However, the risk of false-negative results requires efforts to improve their specificity in parallel with the implementation of countermeasures against the manipulation of the biological samples.


immunoassay; false-negative; drugs; adulteration; urine sample

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About The Author

Stanila Stoeva
Medical university of Varna

Department of Pharmacology, Toxicology and Pharmacotherapy, Faculty of Pharmacy

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