CASE FILES – Xylazine

Toxicology Case Files from the Utah Poison Control Center

Teaching Points

• Opioid overdoses involving xylazine did not have more hypotension or bradycardia compared to opioids alone
• Xylazine-involved overdoses were less likely to experience cardiac arrest
• There was no difference in coma between the two groups
• While not studied in this paper, xylazine may cause alpha-2 agonist withdrawal symptoms and is also associated with severe, necrotic skin lesions

Opioid overdoses involving xylazine in emergency department patients: a multicenter study¹

Xylazine has been found in the opioid supply in most of the US. While some xylazine has been found in powdered fentanyl (usually not M-30 fentanyl tablets) in Utah, it is not yet as common as in states in the Northeast.

Xylazine is an alpha-2 agonist with actions similar to clonidine or dexmedetomidine. It has been implicated in severe, necrotic skin lesions as well as withdrawal not treated with opioid agonists. Though mechanistically, we might expect to see more bradycardia, hypotension, and coma in patients with xylazine-associated opioid overdoses, this had not been previously investigated.

EDs from 7 states (PA, NY, NJ, MI, MO, CA, & OR) screened suspected opioid overdoses receiving naloxone in the ED or requiring ED care, and conducted testing for over 900 drugs by various LC/MS methods.

Xylazine was most prevalent in the Northeast (33% of cases xylazine positive) and Midwest (26%) compared to the West (3%).

There was no difference in initial, total, or number of naloxone doses between xylazine and non-xylazine-associated overdoses. Nor was there any difference in heart rate, respiratory rate, or blood pressure. Fentanyl was the opioid most commonly detected across all cases (95%).

There was no difference in rates of intubation, coma, death, or length of hospitalization. However, xylazine-absent cases were more likely to suffer cardiac arrest (14.3% vs 4.4%). The authors hypothesized that patients in the xylazine group were exposed to less total opioid and thus may have been less likely to suffer respiratory then cardiac arrest.

For now, it appears difficult to suspect xylazine involvement based on presenting symptoms following an opioid overdose. Some patients do report prolonged sedation after using fentanyl adulterated with xylazine. They may also develop severe necrotic wounds or suffer from alpha-2 agonist withdrawal following cessation of opioid use.

Reference

1. Love JS, Levine M, Aldy K, et al. Opioid overdoses involving xylazine in emergency department patients: a multicenter study. Clin Toxicol (Phila). 2023;61(3):173-180. doi:10.1080/15563650.2022.2159427