Withdrawal Signs and Symptoms Among Patients Positive for Fentanyl With and Without Xylazine.

Background: Xylazine is not approved for human use, yet it has emerged as a common adulterant of illicit fentanyl. It is currently unclear whether there is a withdrawal syndrome associated with xylazine and the potential impact of fentanyl coexposure.

Methods: A retrospective cohort study of patients with opioid use disorder admitted to an inpatient medically monitored withdrawal facility was performed. Patients positive for fentanyl were compared to patients copositive for fentanyl and xylazine. Outcomes were self-directed discharge and completion of treatment. Independent variables included Clinical Opioid Withdrawal Scale (COWS) scores, heart rate, and blood pressure. Associations between individuals with or without xylazine were measured.

Results: Among 71 patients admitted for opioid withdrawal management positive for fentanyl, 51.4% were copositive with xylazine. There was no difference detected in average COWS scores (P = 0.12-0.78) or average heart rate (P = 0.33-0.80) between groups. Xylazine copositive patients had higher average systolic blood pressure on days 1 (129.0 vs 123.0, P = 0.01) and 2 (127.9 vs 116.3, P = 0.04) although unclear if clinically meaningful. Individuals copositive for xylazine were less likely to complete treatment (43.2% vs 55.9%, P = 0.23) and more likely to have self-directed discharge (67.6% vs 44.1%; OR, 2.64; 95% CI, 1.0-6.9) although not statistically significant.

Conclusions: Among 71 patients admitted for medically monitored withdrawal, individuals who were copositive for xylazine at the time of admission had higher average blood pressure and were more likely to have a self-directed discharge. Additional research is needed to determine the impact of xylazine on withdrawal.