According to a recent publication, what is the proposed mechanism of why higher serum concentrations of fentanyl were found in overdose patients with xylazine as an adulterant compared to overdose patients without xylazine in the supply?
Xylazine, an 𝛂-2 agonist, is hypothesized to release less potent endogenous opioids which act as a partial competitive opioid receptor antagonist, so larger doses of fentanyl is required to cause respiratory depression.
Hays, H. L., Spiller, H. A., DeRienz, R. T., Rine, N. I., Guo, H. T., Seidenfeld, M., … Smith, G. A. (2024). Evaluation of the relationship of xylazine and fentanyl blood concentrations among fentanyl-associated fatalities. Clinical Toxicology, 62(1), 26–31. https://doi.org/10.1080/15563650.2024.2309326
Contributed by Herbert Wan, PharmD, PGY1 Toxicology/Emergency Medicine Fellow, FL/USVI Poison Information Center Jacksonville