Drug checking as a potential strategic overdose response in the fentanyl era.

Adulteration of illicit drug supplies with synthetic opioids such as fentanyl has contributed to a dramatic rise in overdose morbidity and mortality in North America. One promising response to this crisis is the implementation of "drug checking" services. Drug checking encompasses a range of interventions used to assess the constituents of illicit drug samples, such as colour-spot testing, gas or liquid chromatography, and various methods of spectroscopy. Testing may be performed on-site at events or harm reduction service locales, performed independently by consumers, or sent to a centralized lab for analysis. This information may then serve to inform individual decision-making, enhance harm reduction efforts and strengthen public health surveillance and response strategies to prevent harms associated with illicit drug use. Historical examples of drug checking services that emerged with the 1990s synthetic "party drug" movement in Europe provide a theoretical and practical basis for the adaptation of these services for use in context of the current opioid overdose crisis. Potential harm reduction benefits of drug checking for synthetic opioid adulterants include individuals being more likely to use drugs more safely or to dispose of drugs found to contain harmful adulterants. Public health benefits of drug checking may also include negative feedback on the illicit drug supply with decreased availability or consumption of drugs from sources adulterated with synthetic opioids following public health warning campaigns. As part of the response to the current synthetic opioid epidemic in BC, pilot efforts are being undertaken in Vancouver to determine the feasibility and effectiveness of drug checking as an overdose response strategy. Models of drug checking service delivery and comparison of differing technologies, including unique challenges and potential solutions related to access to these services, legal obstacles, and sensitivity and specificity of testing technologies, are explored, alongside suggestions for future research and directions.