The current opioid crisis has been worsened by the addition of other drugs and substances, including other illicit drugs. There has been a reported rise in the incidence of overdoses from fentanyl, heroin, and other drugs being combined with xylazine, a nonopioid veterinary tranquilizer that is not approved for human use. The drug is added to opioids to purportedly lengthen their euphoric effect. According to the National Institute on Drug Abuse, overdose deaths linked to xylazine started in the eastern United States and spread west, with the largest impact still seen in the Northeast.
Street names for xylazine include tranq, tranq dope, Philly dope, and zombie drug. Xylazine has a chemical structure similar to clonidine, and like clonidine it acts as a central [alpha]2-adrenergic receptor agonist in the brainstem. This causes a rapid decrease in the release of norepinephrine and dopamine in the central nervous system.
Overdose from xylazine can lead to drowsiness, amnesia, respiratory depression, bradycardia, hypotension, hypothermia, miosis, and elevated blood glucose levels. When xylazine is taken in combination with opioids and other central nervous system depressants (such as alcohol or benzodiazepines), the risk of a fatal overdose is increased. The respiratory symptoms of an opioid overdose and a xylazine overdose are very similar. One problem for emergency health care providers is that because xylazine is not an opioid, it does not respond to naloxone-the antidote for opioid overdose. It is not recommended to use a veterinary medicine (such as yohimbine hydrochloride or tolazoline hydrochloride) for reversing xylazine overdose as it is unknown if these drugs are safe or effective in humans. Another problem for emergency health care providers is that xylazine does not show up on routine toxicology screens, only in specialized toxicology tests.
Repeated use of xylazine or drug combinations with xylazine via injecting, snorting, swallowing, or inhaling can lead to severe necrotic skin ulcerations. These ulcerations look different from typical cellulitis or abscesses and may form in areas of the body that are not the site of the injection. Xylazine dependence occurs from repeated exposure and suddenly stopping the drug will lead to severe withdrawal symptoms.
Nurses who work in EDs should consider xylazine overdose if a patient believed to have overdosed on opioids does not respond to naloxone treatment. Xylazine abuse should also be considered if the patient has unique, severe necrotic skin ulcerations. To assist in tracking the severity of this problem, all adverse effects from possible illicit xylazine exposure should be reported to the FDA's MedWatch program at http://www.accessdata.fda.gov/scripts/medwatch/index.cfm.
To read the FDA's full warning letter, go to http://www.fda.gov/media/162981/download.