Tusi: a new ketamine concoction complicating the drug landscape.

A drug concoction called tusi has emerged in Latin America and in Europe and is now beginning to acquire popularity in the United States. "Tusi" is a phonetic translation of "2C," a series of psychedelic phenethylamines. The concoction is also sometimes referred to as "pink cocaine" as it typically comes in the form of pink powder. However, despite its name, the concoction rarely contains 2C series drugs. Multiple drug checking studies have found that the majority of tusi samples contain ketamine, often combined with 3,4-methylenedioxymethamphetamine (MDMA), methamphetamine, cocaine, opioids, and/or new psychoactive substances. The tusi phenomenon complicates the drug landscape because it has the potential to confuse both people who use it and researchers alike. People using may think the drug is 2C/2C-B, and they may also be unaware that the concoction tends to consist of ketamine and a wide variety of other drugs. Unintentional exposure to its contents can lead to increased risk of adverse effects. The tusi phenomenon also has the potential to complicate drug research as unknown exposure to drugs like ketamine and MDMA will lead to underreporting of use. A combination of self-report and toxicological testing may be needed to inform the most accurate estimates of use. Both researchers and people at risk for use need to be informed about this new concoction. Drug researchers need to be cognizant about the way they query use, and people at risk for using need to be educated about the possible contents of tusi and associated dangers.