Strychnine as an Emerging Adulterant in the Illicit Fentanyl Drug Supply

Awareness of strychnine as an emerging adulterant is extremely important given its unique clinical findings and morbid clinical sequelae. Strychnine was historically utilized as a tonic, laxative, rodenticide, and adulterant in cocaine, heroin, and methamphetamine. This report describes a cluster of patients with acute opioid overdose presenting to an inner-city medical center with strychnine on serum testing. The data for this case series are from the Toxicology Investigator Consortium Fentalog Study, a 2020-2025 study of patients aged ≥18 years evaluated in 10 regionally distinct emergency departments after a suspected opioid overdose. Comprehensive toxicology testing was performed on residual serum samples. Of the 111 cases submitted by all participating sites in January 2023, 4 cases from the Denver, CO site detected strychnine on comprehensive toxicology testing. The total cases from all sites in January 2023 were 921. The presence of strychnine in biological samples of patients utilizing opioids in this report indicates a possible reappearance in its use as an adulterant, warranting further investigation and public preventative health vigilance. Knowledge of local illicit adulterants is crucial for public healthcare providers because it enables them to consider anticipated clinical course and life-saving interventions.