Illicit opioid adulterant trends in patients presenting with acute opioid overdose

Clandestine fentanyl manufacturing oftentimes introduces adulterants and contaminants. This article aims to evaluate trends in adulterants from a cohort of patients presenting to the emergency department (ED) with illicit opioid overdose across the United States. The Fentalog Study group is a multicenter toxicology study group which evaluated ED patients with suspected opioid overdose at 10 medical centers across the United States between 21 September 2020 through 5 February 2024. Comprehensive qualitative toxicology testing was performed on residual serum specimens. Study sites were divided into three geographic regions: West (California, Oregon, Colorado), Midwest (Missouri, Michigan), and East (New York, New Jersey, Pennsylvania, Georgia). Illicit opioids were defined as fentanyl and fentanyl analogs, heroin or its metabolites, and/or novel potent opioids such as nitazenes. 1295 patients with confirmed illicit opioid overdose were included. Males accounted for the majority (73.7%) of patients. The median age was 39 (IQR: 31-54) years. Adulterants were detected in 745 (57.5%) patients. Quinine was the most abundantly encountered adulterant (433; 33.4%). Antihistamines were the most frequently detected class of adulterants (19.6%). There were significant differences in adulterants detected across the three time periods, with notable decreases in adulterants from time-period 1 (79.5%) to time-period 3 (41.7%; P < .001). Adulterants were found in 84 (27.0%) of patients that presented to a hospital in the Western United States, compared with 181 (24.3%) in the Midwest, and 480 (64.4%) of patients in the East (P < .001). Patients with concurrent cocaine were more likely having an adulterant present than those without cocaine present (OR 1.23; 95% CI 1.15-1.31). In contrast, patients with illicit opioids and concurrent methamphetamine were less likely to have adulterants present (OR 0.89; 95% CI 0.84-0.95). Adulteration of illicit opioids was more likely in the Eastern United States and for those with concurrent cocaine and opioid exposures.