Xylazine in the Unregulated Drug Supply

"Xylazine is a veterinary tranquilizer, which is not approved for human use in the United States, but is commonly used for sedating large animals (Reyes et al., 2012; Ruiz-Colón et al., 2014). Although human intoxication with xylazine has been reported sporadically over the past several decades in a number of case studies (Ruiz-Colón et al., 2014; Forrester, 2016), it was first described as a more prevalent additive in the unregulated drug supply of Puerto Rico (Reyes et al., 2012; Rodríguez et al., 2008; Torruella, 2011). It was also noted in the literature describing drug overdose deaths in Philadelphia as early as 2006, yet it did not appear in high prevalence at that time (Wong et al., 2008). However, since the mid-2010s, xylazine has been noticed by people who inject drugs (PWID) and public health practitioners as an increasingly commonplace additive in the street opioid supply of Philadelphia (Johnson et al., 2021). Further, recent reports from Connecticut implicated xylazine in a rising fraction of overdose deaths in 2019–2020 (Nunez et al., 2021; Thangada, 2021). A report released in September 2021 leveraged data from 38 states and Washington DC representing the year 2019, and found xylazine to be present in 1.8% of overdose deaths (Kariisa, 2021). However, no time trends were provided, and results were not disaggregated below the level of US Census Region, with limits the usefulness of the results for frontline providers and harm reductionists. Additionally, reports from Philadelphia and Connecticut, as well as media reports from numerous cities, suggest that xylazine-present overdose have increased sharply in 2020–2021."