Mental health | Xylazine intensifies Opioids effects in study

Mental Health | Xylazine, a veterinary sedative that is not approved for human use, has been found to potentially worsen the life-threatening effects of opioids,...

...according to a study in rats that was released by the National Institutes of Health.

The study’s findings, which were published in the journal Psychopharmacology, imply that when used in combination with opioids such as fentanyl and heroin, xylazine could impair the brain’s ability to receive oxygen and potentially lead to death.

In recent months, xylazine has been increasingly detected in illicit opioid supplies. At the Rx and Illicit Drug Summit in April in Atlanta, Georgia, Rahul Gupta, MD, MPH, MBA, FACP, director of the Office of National Drug Control Policy announced that ONDCP was designating the combination of fentanyl and xylazine as an emerging drug threat to the United States. The designation set the wheels in motion for a whole-of-government plan with deliverable actions to address the issue. The plan is due to be published in July of this year.

The study conducted within the National Institute on Drug Abuse’s (NIDA) Intramural Research Program was a multi-stage investigation. In the first stage, xylazine was administered on its own and in different doses to assess its effects on movement, temperature, and oxygen levels in the brain. Known effects, including sedation, muscle relaxation, and decreased body temperature, were observed even at low doses. Decreases in oxygen levels in the brain became stronger as more xylazine was administered.

In the study’s second phase, either fentanyl or heroin were administered. Initial rapid and strong decreases in brain oxygen levels were observed after administration of fentanyl or heroin.

When mixtures of either fentanyl and xylazine or heroin and xylazine were administered, a rebounding increase in oxygen to the brain was eliminated, leaving brain oxygen levels lower for a prolonged period compared to fentanyl or heroin alone. The combination of heroin and xylazine also produced a much stronger and prolonged initial decrease in brain oxygen compared to heroin alone.

“The risks that people face from a drug contaminated with fentanyl are very concerning, and this study provides evidence to suggest that the addition of xylazine is exacerbating those risks,” lead author Eugene A. Kiyatkin, MD, PhD, senior associate scientist in the NIDA Behavioral Neuroscience Branch, said in a news release.

“Further research is needed to explore how these observations may apply in humans, and to continue to parse the complex role of illicit drug combinations with xylazine and risk of overdose.”
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