Two years after it was first detected in Europe in January 2019, researchers at the National University of Singapore (NUS) have identified three biomarkers for APP-BUTINACA (also called APP-BINACA), an emerging synthetic cannabinoid.
APP-BUTINACA appeared in the United States just two months after it was first seen in Europe. It was identified for the first time in blood sample extracts from forensic casework by a team at the Center for Forensic Science Research and Education (CFSRE) and NMS Labs using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). According to CFSRE, there are two structurally similar synthetic cannabinoids—ADB-PINACA and MDMB-BINACA—that share the same formula and parent mass with APP-BUTINACA. But, their chemical behavior and mass fragmentation patterns differ, allowing for differentiation during analytical testing.
Subsequent to its discovery in biological samples, the synthetic cannabinoid was detected and characterized in seized drug material by GC-MS, LC-QTOF-MS, and nuclear magnetic resonance (NMR) spectroscopy. Further analysis resulted in the identification of 5 metabolites, including 4-HO-APP-BINACA and APP-BINACA 3-phenylpropanoic acid. However, as most synthetic cannabinoids are extensively metabolized in the body after consumption, they become virtually undetectable in urine samples—even with metabolites available as reference standards.
So, when APP-BUTINACA made its way over to Singapore last year, NUS professor of pharmacy Eric Chan employed a new method of detection based on pharmacokinetics.
Rather than chemically synthesize metabolites of the cannabinoid, Chan and his team used human liver enzymes to synthesize metabolites of ADB-BUTINACA. According to their study, published in Clinical Chemistry, the method successfully identified 15 metabolites of ADB-BUTINACA, as well as their respective pathways of biotransformation in the body.
Of the 15 new metabolites, the researchers proposed four as urinary metabolite biomarkers due to their metabolic stability, including one with a reference standard already available. While there are three existing metabolites of ADB-BUTINACA available for routine forensic monitoring, they are typically absent or found at very low concentrations in urine samples. These four biomarkers are the first to be identified specially for urine analysis.
The team says a commercial panel comprising either one or a combination of the four urinary biomarkers can help detect the consumption of ADB-BUTINACA. Additionally, they believe their approach can be leveraged for other existing and new synthetic cannabinoids.
“Prior to our study, the metabolism and urinary biomarkers of ADB-BUTINACA were unclear,” said Chan.
“Our discovery and unique methodology offer assistance to the forensic fraternity who is constantly being challenged by the emergence of novel synthetic cannabinoids, and can also bring benefits to the international public communities to tackle the increasing abuse of this synthetic cannabinoid. This will bring us closer to the goal of having a drug-free world.”
Moving forward, Chan said the team plans to extend their current strategy to better understand the disposition of novel metabolites of synthetic cannabinoids by kidneys and their eventual occurrence in urine.
Photo: Eric Chan (middle) led the research, which was conducted in collaboration with the Health Sciences Authority (HSA). The research team included Moy Hooi Yan (extreme left), HSA’s laboratory director of the analytical toxicology lab - drug abuse testing, and Wang Ziteng (extreme right), research fellow at the NUS Department of Pharmacy. Credit: National University of Singapore