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Overcoming the screening challenges of new psychoactive substances

Overcoming the Screening Challenges of New Psychoactive Substances

The “designer drug” (referred to as new psychoactive substances or NPS by government agencies) phenomenon started decades ago with the development and production of drugs that mimic the effects of controlled drugs (such as amphetamines, cocaine, cannabis and heroin) but avoid legislation based on different chemical structures. There are now hundreds of such substances available via the Internet and they create a number of global analytical and legislative challenges.

The laboratory challenge is focused on the detection and identification of a variety of chemical structures that are associated with NPS. Immunological techniques that have been successful for screening traditional drugs require significant redesign for NPS. Presumptive detection requires the use of specific and selective techniques such as gas or liquid chromatography with mass-spectrometry for accurate identification, especially in a forensic and medicolegal setting.

The challenge of these techniques revolves around the choice of targeted (specific) or non-targeted (more general) analytical screening procedures. Targeted techniques use increased specificity to detect NPS present at very low concentrations, which is a necessary requirement for analysis of synthetic cannabinoids and other potent NPS such as LSD derivatives and other drugs with hallucinogenic effects. Non-targeted techniques allow for the detection of a very wide range of substances but can be inhibited by sensitivity, which is not always a problem for many NPS as many users ingest significant doses. Consequently, the laboratory will select the most appropriate analytical techniques, and may use a combination of them to ensure effective analysis of NPS. Newer techniques involving high resolution mass spectrometry to measure mass assist with elucidation of chemical structures, including metabolites in blood and urine.  

In recent years, the increasing use of NPS has meant that detection now needs to be conducted in a number of different settings, from drug abuse clinics to post-mortem and criminal casework.

The fact that NPS are challenging to detect has made them the drug of choice in certain situations, including workplace or prison environments.

However, improvements in detection capabilities and screening tools, as well as increased awareness of NPS, have improved detection of these substances. This is especially important when determining their role in deaths, which may have previously been missed or underestimated. The presence of multiple drugs (including other NPS) presents additional analytical as well as interpretative challenges to toxicologists.    

Although there has been an increase in the number of NPS that have been internationally controlled, there have also been changes in national legislative approaches. Specifically, whilst there has been some generic control based on analogue or chemical similarities, some countries (most recently the UK) have applied legislation based on the psychoactive effect rather than chemistry alone. The effectiveness and outcomes of this approach will be interesting to monitor. Regardless of the legislative method employed by a country, an appropriate and effective laboratory testing protocol can positively support the ultimate goal of identifying and controlling NPS.

   

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