Occult bromazolam exposure in patients presenting with opioid or stimulant overdose.

Introduction: Bromazolam is a benzodiazepine, not approved for use in any North American or European jurisdiction that has emerged as an adulterant in the United States illicit drug supply.

Methods: This is a case series of seven patients treated for an acute overdose and found to have bromazolam in their blood despite no self-reported exposure. Patients were enrolled from June 2023 to January 2024 as part of the Drug Overdose Toxico-Surveillance Reporting Program, a multi-center, prospective project including patients aged 13 years and older with a suspected life-threatening opioid and/or stimulant overdose. This case series is drawn from a single emergency department from that project. Patients were interviewed on their drug use, and clinical data were collected from electronic medical records. Whole blood was obtained and tested qualitatively for over 1,200 psychoactive substances using liquid chromatography quadrupole time-of-flight mass spectrometry and quantitative measurements using liquid chromatography-tandem quadrupole mass spectrometry.

Results: Patients presented with acute signs of excessive sedation (six of seven) or agitation (one of seven). The median blood bromazolam concentration was 29 µg/L (range <5-84 µg/L). Three patients were admitted to hospital or observed for more than 24 h in the emergency department. The reasons for admission/observation were advanced pregnancy, prolonged sedation, and the need for social services. No patients were placed in a critical care unit and all patients survived. During the structured interview, none of the patients reported bromazolam use.

Discussion: This case series demonstrated no poor clinical outcomes in patients with acute overdose who had detectable bromazolam concentrations despite no reported bromazolam use. In all cases of sedation, patients responded to naloxone (in all cases the patients admitted to taking opioids, which was confirmed analytically), and there was no ongoing sedation attributed to the detected bromazolam.

Conclusions: Substances unknown to patients are present in the drug supply. Toxico-surveillance programs are essential to obtaining information about community patterns of drug use that cannot be obtained from patient history or from medical charts.