Novel Psychoactive Substances: Testing Challenges and Strategies

To keep up with emerging NPS, toxicology labs must develop robust assays and update existing testing panels and menus

Photo portrait of Pallavi Upadhyay, PhD
Pallavi Upadhyay, PhD

Pallavi Upadhyay, PhD, is an infectious disease scientist and researcher, scientific and medical writer, and consultant. In her full-time role as the director of scientific and clinical affairs at HealthTrackRx...

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Published:Nov 16, 2021
|Updated:Nov 23, 2021
|6 min read

While advances in modern chemistry and pharmacology have led to the invention of life-saving drugs, they have also led to the synthesis of new or novel psychoactive substances (NPS). NPS are often manufactured in clandestine laboratories without quality or regulatory guidelines, thus their chemical structures, composition, and adverse side effects are not fully understood. Lack of timely identification can be attributed in part to their fast turnover rate—by the time the biochemical and toxicology research is complete on an NPS, it either vanishes from circulation or is modified to a new version to circumvent restrictions. This makes it difficult to monitor and regulate these counterfeit drugs.

For example, in early September 2021, there were reports of fake Xanax® containing the NPS flualprazolam or flubromazolam (both known to cause central nervous system depression and fatal intoxications) instead of alprazolam, which is the main certified benzodiazepine in Xanax®.

To keep up with testing and detection of these compounds, clinical toxicology laboratories need to develop robust, rapid, and high-throughput assays and update the existing testing panels, assays, and menus. Stringency and centralizing the laws and regulations for not only restricting the usage but also forecasting trends and monitoring NPS trade and prevalence will be instrumental for better preparedness in terms of education, training for health care professionals and policymakers.

What are novel psychoactive substances?

The term “novel psychoactive substances” can be misleading, suggesting that NPS are a new phenomenon; however, these substances have been available for decades. NPS are a broad class of recreational compounds that have emerged as a legal or cheaper alternative to prescription or illicit drugs. Their usage became further evident when synthetic cannabinoids emerged as cannabis alternatives in the early 2000s, and were an instant success due to their legal status. As a result, hundreds of lab derived experimental NPS entered the illicit market. These drugs are often marketed as “legal highs,” “research chemicals,” or “designer drugs.”

By the end of 2019, about 950 novel psychoactive substances were identified and being sold mostly in the American and European markets. Currently, the main categories of NPS include:

Synthetic cannabinoid receptor agonists

Also known as SCRA, "Spice," "K2," and "Kush," these cannabinoid NPS were originally designed to mimic the effects of cannabis.


A vast group of NPS (including phenylethylamines, cathinones, and aminoindanes, also known as “bath salts,” and piperazines), stimulants impact the central nervous system, causing euphoria, hallucinations, alertness, etc. Some of the well-known stimulants are 3C-bromo-Dragonfly (an MDMA or ecstasy derivative), methiopropamine (a methamphetamine analog), and meta-chlorophenylpiperazine (an antidepressant derivative).

Synthetic opioids

These are pharmacologically and chemically similar to natural opioids (mainly morphine and codeine). One of the first and highly potent synthetic opioids, fentanyl, was manufactured for medicinal purposes in 1974 and is 50-100 times more potent than morphine. Since then, several fentanyl analogs have been introduced, including carfentanyl, which is 10,000 times more potent than morphine. These analogs often come laced with heroin and can be found in many other deadly combinations and are one of the prime reasons for the rise of the opioid epidemic.


Sedatives/hypnotics are central nervous system depressants. The most popular substances in this class are synthetic benzodiazepines, such as flubromazepam.


Lysergic acid diethylamide (LSD), N,N-Dimethyltryptamine (DMT), and similar psychedelics belong to the class of hallucinogens. NPS in this category mostly mimic LSD and DMT, including methoxetamine (MXE), N-methoxybenzyl (NBOMe), alpha-methyltryptamine (AMT), and 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT).

NPS availability and impact on human health

Usage of NPS worldwide has surged substantially in the last decade, with the majority of users being either current users of conventional illicit drugs (such as heroin, cannabis, cocaine, methamphetamine, etc.) or patients with substance use disorders. Recent studies have shown that individuals with mental illness are more likely and prone to use NPS than those without any mental illness, suggesting a correlation between NPS usage and mental health. For any phenomena to be successful, the main driving force is demand, which is constantly increasing for NPS due to high potency, ease of availability, and avoidance of detection. Supply for this demand is easily fulfilled due to cheaper production costs and favorable legal status as compared to conventional drugs. Advances in information technology have fueled the fire and contributed tremendously to the NPS explosion in recent years.

According to Dr. Charles Mikel, founder and principal consultant at NightMaker Science®, who brings more than 12 years of expertise to the field of clinical toxicology, "NPS pose great health risks, ranging from mental health disorders to poisoning, severe damage to the nervous system, emergency room visits, and even mortality. NPS purchased on the street or internet are cheap but may not even contain what they claim to." Despite the drastic prevalence, the long-term health repercussions of NPS are largely unknown.

Challenges for NPS drug testing and monitoring

"Among the main challenges for clinical testing are the sheer number and variety of NPS currently available and the rate at which new ones appear on the market. Because laboratories can only develop tests for NPS after they have already appeared on the market, testing is perpetually lagging behind the available NPS varieties,” says Mikel. “Laboratories are left chasing after ever-changing targets."

At present, clinical drug testing is broadly divided into qualitative and quantitative screening/tests for compliance drug monitoring (CDM). Qualitative tests are point-of-care (POC) immunoassays that identify the drug classes present in a specimen. Identification of NPS via POC testing would pose a greater challenge since these assays are mainly designed and targeted to identify conventional drug classes (e.g., amphetamines, opioids, benzodiazepines, etc.). Therefore, NPS would not be detected by POC due to the difference in chemical structure as compared to conventional drugs or due to cross-reactivity with immunoassays, leading to false positive or false negative results.

Some commonly used quantitative tests for CDM include gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). These traditional tools for analyses require preestablished libraries (with known compounds’ chemical structure, mass, composition, etc.) that are compared to an “unknown” substance to identify the compound of interest. In addition, reference standards and validations (for each compound/category) are required to further assess a compound’s specificity and quantitation, after which a testing menu/panel (with pertinent compounds and their categories) is established based on the prevalence of conventional drugs of misuse. 

Challenges faced by toxicology laboratories in NPS identification:

  • Sample preparation: NPS are found in several forms (e.g., pills, liquid, powders, capsules, gels, sprays, crystals, and “herbal blends”), and establishing and streamlining purification workflows for further experiments can be cumbersome.
  • Method/protocol development: the chemical structure of each NPS would be needed to validate each test. In many cases, isomer separation assays are required to differentiate structural analogs.
  • Lack of reference material: establishing and keeping up with reference/standards for each NPS is neither feasible nor cost-effective.
  • Limit of detection/test panel: establishing the limit of detection for each NPS in a targeted test panel can be arduous and ineffective due to the regular modification and “recycling” of NPS.

Strategies and tools that can help identify NPS include:

  • Implementing sophisticated sample preparation techniques (e.g., solid phase extraction and liquid-liquid extraction) to target nonbiological material.
  • Using targeted and updated ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) methods to enable higher throughput than traditional LC-MS/MS.
  • Employing high-resolution mass spectrometry (HRMS) such as LC-HR/MS. Because this technique can precisely distinguish between two compounds with the same molecular mass, LC-HR/MS is becoming a popular technique to detect “unknown” compounds. In this case, tentative identification of the compound of interest can be performed without the availability of a reference standard or a preestablished library. Other HRMS-based tools used for NPS testing include time-of-flight (TOF) mass analyzers (TOFMS), Orbitrap MS, and Fourier transform ion resonance (FT-IR) mass spectrometry.
  • To better understand how an NPS affects metabolism and to complete toxicological profiling, in vitro and in vivo studies in mammalian model systems are recommended.

Together, these analytical techniques can help produce a complete compound profile for NPS, especially when used in tandem, where each instrument/technique provides a unique perspective of the compound of interest. For example, using GC-MS analysis followed by FT-IR, coupling nuclear magnetic resonance (NMR) with LC-HR/MS and Ramen spectroscopy, or conducting in vivo experiments in conjunction with HRMS for NPS characterization.

NPS awareness and regulations

Any new pharmaceutical drug undergoes multiple rounds of safety and quality checks, as well as clinical trials before human application. On the other hand, because NPS are manufactured illegally as derivatives of controlled substances with a clandestine chemistry to circumvent legislation, they do not meet these quality standards and thus pose a threat to public health. The complete extent of their harm is still unknown, and due to ethical and legal restrictions, controlled studies or clinical trials to investigate their effects are improbable.

Organizations that monitor NPS and provide updates include:

  • United Nations Office on Drugs and Crime (UNODC)
  • European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)
  • United States Drug Enforcement Administration (DEA)

Photo portrait of Pallavi Upadhyay, PhD
Pallavi Upadhyay, PhD

Pallavi Upadhyay, PhD, is an infectious disease scientist and researcher, scientific and medical writer, and consultant. In her full-time role as the director of scientific and clinical affairs at HealthTrackRx company, she oversees the development and implementation of diagnostic assays and clinical studies. She also directs the research and development and scientific publication initiatives in the company. Dr. Upadhyay holds a PhD in molecular biology from Texas Woman’s University. Her professional expertise and interest include molecular diagnostics and techniques, molecular microbiology, advanced data analytics, and scientific writing.


Cannabis ResearchDrug MonitoringDrug TestingOpioidsToxicology
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