Analytical Challenges and Health Implications of "Tusi" (2C): A Critical Review

"Tusi," commonly known by various names such as "pink cocaine," "cocaina rosada," "Tucibi," "pink powder," "Eros," and "Venus," is a psychoactive mixture of substances that first appeared in Colombia around 2010. Since its emergence, its use has expanded across Latin America, the United States, Australia, parts of Southeast Asia and Europe, with notable prevalence in Spain. The composition of "Tusi" is highly variable and often unpredictable, leaving users unaware of its exact chemical constitutes and the associated pharmacological and physiological risks. Frequently mischaracterized as a solely product of the 2 C class of phenethylamines, it is typically a mixture of ketamine, 3,4-methylenedioxymethamphetamine (MDMA), amphetamine (AMP), methamphetamine (MAMP), and occasionally cocaine, opioids, or other new psychoactive substances (NPS). Notably, in Australia, 133 kg of "pink cocaine" were seized in 2024, with ketamine and MDMA purities ranging from 6.8% to 51.3% and 15.8% to 33.2%, respectively. Additionally, in the US, the Drug Enforcement Administration (DEA) has seized 960 samples of "Tusi" since 2020. Of these, only four were confirmed to contain 2,5-dimethoxy-4-bromophenethylamine (2 C-B), which is the most anticipated compound from the 2 C family. Given its widespread global availability and the scarcity of scientific literature on this mixture, this critical review aims to present a detailed profile of "Tusi". It examines its composition, its associated health risks, and the current methodologies employed for its detection. Additionally, it addresses the challenges related to its analysis and proposes alternative societal monitoring strategies, such as the application of drug-use biomarkers in wastewater streams.