The agency issued an import alert, which gives it the power to detain raw ingredients or bulk finished product if the shipments are suspected to be in violation of the law. Xylazine was first approved by the FDA in 1972 as a sedative and analgesic for use only in animals.
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It is increasingly being detected and is usually mixed with fentanyl, cocaine, methamphetamine, and other illicit drugs. A January 2023 study by Nashville-based testing company Aegis Sciences found xylazine in 413 of about 60,000 urine samples and in 25 of 39 states that submitted tests. The vast majority of xylazine-positive samples also tested positive for fentanyl.
The FDA said it would continue to ensure the availability of xylazine for veterinary use, and the American Veterinary Medicine Association said in a statement that it “supports such efforts to combat illicit drug use.”
FDA Commissioner Robert M. Califf, MD, said in a statement that the agency “remains concerned about the increasing prevalence of xylazine mixed with illicit drugs, and this action is one part of broader efforts the agency is undertaking to address this issue.”
Dr. Robert M. Califf
In November, the agency warned health care providers that because xylazine is not an opioid, the overdose reversal agent naloxone would not be effective. Xylazine acts as a central alpha-2-adrenergic receptor agonist in the brainstem, causing a rapid decrease in the release of norepinephrine and dopamine in the central nervous system. Its use can lead to central nervous system and respiratory depression, said the FDA.
Clinicians have scrambled to treat severe necrotic skin ulcerations that develop at injection sites.
Xylazine is relatively cheap and easy to access, said the Drug Enforcement Administration and Department of Justice in a November joint report. The drug is “readily available for purchase on other Internet sites in liquid and powder form, often with no association to the veterinary profession nor requirements to prove legitimate need,” said the Justice Department. A buyer can purchase xylazine powder online from Chinese suppliers for $6-$20 per kilogram, according to the report.
In 2021, xylazine-positive overdoses were highest in the South, which experienced a 1,127% increase from 2020, the Justice Department reported. The same year, there were 1,281 overdoses involving the substance in the Northeast and 351 in the Midwest.
There were just 34 overdoses involving xylazine in the West in 2021, but its use appears to be growing. The San Francisco Department of Public Health said it had detected low levels of xylazine in four people who died of overdoses in December and January.
“Identifying xylazine in San Francisco is concerning,” said the department in a statement, adding that it had not yet seen evidence of skin wounds in injection drug users in the city.
In late February, the Los Angeles County Department of Public Health issued a warning to first responders and health care professionals that xylazine had been detected in the area’s illicit drug supply.
The department said it will “work closely with other partners to understand the extent of the possible xylazine contamination in the illicit drug supply to increase awareness and education to the public.”
The FDA commissioner said the agency will coordinate with public health officials to more closely track xylazine.
“We will continue to use all tools at our disposal and partner with the Drug Enforcement Administration and other federal, state, local agencies, and stakeholders as appropriate to stem these illicit activities and protect public health,” said Dr. Califf.
A version of this article first appeared on Medscape.com.