Emergence, Diversity, and Control of New Psychoactive Substances: A Global Perspective.

The phenomenon of new psychoactive substances (NPS), which came to the attention of the wider international community at the beginning of the 2010s, has been unprecedented in terms of the sheer number of substances, their rate of emergence, chemical diversity, and range of pharmacological effects. In particular, the chemical diversity has been a challenge to promoting a better understanding of the NPS market - a fundamental requirement for effective policy decisions and interventions. This manuscript highlights the significant chemical diversity of NPS and describes an alternative, complementary, and pragmatic classification based on pharmacological effects, which aligns NPS to traditional controlled drugs and enhances understanding of the phenomenon. It further reviews actions taken at the international level to address the NPS issue, including changes in the scope of control of some NPS and the enhancement of the United Nations Early Warning Advisory on NPS to deal with the dynamics and evolution of the market.