Quetiapine: A Novel Additive to the Illicit Heroin Supply in Los Angeles

The rise of the "fourth wave" of the US overdose crisis has been characterized by the increasing polysubstance use of illicit opioids combined with other drug classes. Polysubstance combinations are increasingly better understood through community-based drug checking. Here we share findings from a drug checking program in Los Angeles, California, highlighting quetiapine-a commonly used atypical antipsychotic-as a novel additive in heroin samples.

This study leveraged data from a community-based drug checking program in Los Angeles, CA. Substance determination was performed through direct analysis in real-time mass spectrometry (DART-MS). Fisher exact tests were used to assess differences in heroin samples containing versus not containing quetiapine.

Of n=52 samples containing heroin, n=13 (25.0%) contained quetiapine. Among quetiapine-positive heroin samples, n=4 (30.8%) contained fentanyl, compared with n=27 (69.2%) quetiapine-negative heroin samples ( P =0.022). No significant differences were observed between quetiapine-positive and negative samples with respect to xylazine, cocaine, or methamphetamine prevalence. All quetiapine-positive samples were identified by clients as expected to contain black tar heroin, and no clients reported expecting their samples to contain quetiapine. Anecdotally, some participants identified increased euphoria and "pins and needles" sensations from quetiapine-positive samples.

This small observational study provides the first drug-checking-based evidence in the academic literature-to our knowledge-of quetiapine as an additive to the illicit heroin supply. The presence of quetiapine was associated with less fentanyl adulteration and may reflect an alternative augmentation strategy. Further confirmatory studies are needed to assess the degree to which this phenomenon exists in other locations and the potential health implications.