Cocaine, heroin, fentanyl… The opioid crisis which has killed more than 500,000 people over the past 20 years continues to worsen in the United States. These drugs particularly affect young people and modest backgrounds, because they are easily accessible and highly addictive. Fentanyl in particular, which has wreaked havoc in the United States and Canada in recent years, is about 50 times more potent than heroin, so the risks of addiction and overdose are significantly higher.
At the start of 2023, it is xylazine, nicknamed “traq” or “zombie drug” which worries the American Medicines Agency in particular. Taken in combination with other drugs, such as opioids or alcohol, its effects are devastating.
A dangerous product often combined with opioids
Xylazine is a compound normally used in veterinary medicine and approved for use in cats, dogs and horses as a sedative or pre-anaesthetic. Not suitable for humans, this drug is an adrenergic agonist: it blocks the function of adrenergic receptors involved in the regulation of blood pressure or heart rate. By stimulating alpha2 adrenergic receptors, xylazine prevents the release of norepinephrine via alpha1 adrenergic receptors. This has the effect of slowing breathing, lowering blood pressure, heart rate and body temperature.
“As soon as we stop stimulating the alpha1 receptors, we have a loss of consciousness, attention, extreme sedation and possibly delusions or hallucinations: this is most certainly why it is called the zombie drug , even if this name is rather erroneous (…)“, explains to Science and Future Jean-Pol Tassin, emeritus research director at INSERM and specialist in addiction and withdrawal. The term “zombie drug” has in fact already been used to characterize other drugs, such as those of the cathinone family, which can cause hallucinations and sedation. In the case of xylazine, this nickname is also justified by the fact that it is responsible for significant skin lesions, which can go as far as necrosis and require the amputation of the affected limbs.
Traffic difficult to control
First described in the early 2000s, recorded overdose cases have only increased since the 2010s, and even more recently since 2020. That same year, xylazine was implicated in 26% of drug overdoses. ‘State of Pennsylvania.
In addition to its very low price compared to other substances, it is very easy to obtain it in the United States. Because it is not intended for human use, it is not as well controlled as other substances such as opioids can be, which is why the FDA has recently taken steps to control its importation into the territory. “We recognize the public health effects of xylazine contamination of these illicit drugs and we continue to ensure that the legitimate product is for veterinary use only.” said Tracey Forfa, director of the FDA’s Center for Veterinary Medicine in a Press release.
Naloxone ineffective
“The problem with this drug and what makes it particularly dangerous is that the interval between the lethal dose and the effective dose is small”, continues Jean-Pol Tassin. This substance taken alone therefore already constitutes a danger in itself, but is even more so when taken with alcohol or opioids. In the United States, certain drugs, in particular fentanyl, can be cut with xylazine without the consumers being informed. In 2021 in Philadelphia, more than 90% seized drug samples contained xylazine.
This substance is all the more problematic as, to date, there is no effective treatment to counter its effects. Naloxone, used as an opioid antagonist, is not effective against xylazine, although its administration remains recommended in the event of overdose (these being often due to the combined intake of xylazine and opioids).
