EMCDDA framework and practical guidance for naming synthetic cannabinoids.

Synthetic cannabinoids (SCs), often sold as "legal" replacements for cannabis, are the largest group of new psychoactive substances monitored by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). Currently, close to 240 structurally heterogeneous SCs are monitored through the European Union (EU) Early Warning System, and attributing consistent, informative, and user-friendly names to SCs has been a challenge in the past. Over time, several naming conventions have been employed with the aim of making SCs more easily recognizable by non-chemists, including regulators. To achieve this, the names assigned need to contain detailed information on the structural features present in the substance. This work provides a theoretical framework and a practical hands-on guideline for consistent naming of SCs, which is easy to understand and can be applied by the forensic community, researchers, clinical practitioners, and policy-makers. The proposed framework builds on the established letter code system for molecular building blocks (core, linker, linked group, and tail) implemented by the EMCDDA in 2013 and has been expanded to incorporate additional structural features through substitution. The scope of the issue of attributing semi-systematic code names is illustrated, and earlier approaches used for naming SCs are discussed. The concepts and rules of the EMCDDA framework are described through a flowchart that provides a basis for naming new SCs, a graphical overview of the chemical diversity of SCs, and a detailed list of the SCs identified in the EU by the Early Warning System of the EMCDDA for reference.