Clinical value of analytical testing in patients presenting with new psychoactive substances intoxication.

New psychoactive substances (NPS) have emerged worldwide in recent years, posing a threat to public health and a challenge to drug policy. NPS are usually derivatives or analogues of classical recreational drugs designed to imitate their effects while circumventing regulations. This article provides an overview of benefits and limitations of analytical screening in managing patients presenting with acute NPS toxicity. NPS typically cannot be analytically identified with the usual immunoassay tests. To detect NPS using an immunoassay, antibodies specifically binding to the new structures would have to be developed, which is complicated by the rapid change of the NPS market. Activity-based assays could circumvent this problem since no prior knowledge on the substance structure is necessary. However, classical recreational drugs activating the same receptors could lead to false positive results. Liquid or gas chromatography coupled with mass spectrometry is a valuable NPS analysis tool, but its costs (e.g. equipment), run time (results usually within hours vs minutes in case of immunoasssays) and the need for specialized personnel hinder its use in clinical setting, while factors such as lack of reference standards can pose further limitations. Although supportive measures are sufficient in most cases for adequate patient management, the detection and identification of NPS can contribute significantly to public health and safety in cases of e.g. cluster intoxications and outbreaks, and to the investigation of these novel compounds' properties. However, this requires not only availability of the necessary equipment and personnel, but also collaboration between clinicians, authorities and laboratories.