Drug checking to detect fentanyl and new psychoactive substances

PURPOSE OF REVIEW: Drug checking services invite drug consumers to anonymously submit drug samples for chemical analysis and provide feedback of results. Drugs are tested for strength/dose and/or presence of adulterants. Drug checking appears to be more common in recent years in response to increases in fentanyl-related deaths and the proliferation of new psychoactive substances (NPS). We aim to provide information regarding the current state of drug checking in relation to analysis methods, adulteration rates, and behavioral responses to results. RECENT FINDINGS: Various technologies are being used to detect the presence of fentanyl, its analogs, and other NPS in drug samples. Proxy drug checking, which we define as biospecimen testing for drug exposure postconsumption, is also becoming common. However, there appears to a dichotomy between research focusing on populations at high risk for fentanyl exposure and to exposure to NPS such as synthetic cathinones. SUMMARY: Drug checking research and services largely focus on opioid consumers and nightclub and dance festival attendees, but more focus may be needed on the general population. Drug checking results can inform surveillance efforts, and more research is needed to overcome barriers to drug checking and to focus on whether test results indeed affect behavior change.