The Wall Street Journal reports that the veterinary tranquilizer xylazine, which users call tranq, has been increasingly reported among drug overdose victims, particularly on the East Coast. This very potent tranquilizer has been mixed in with illicit fentanyl which, in turn, is often mixed in with other illegal drugs such as cocaine and methamphetamine. The sedative properties of the drug greatly enhance the narcotic effects of opioids. Therefore, the drug cartels have been adding it to opioids to reduce the dose of opioids necessary to create a high. The enhanced potency allows the cartels to smuggle illicit fentanyl and other opioids in smaller sizes and increase the number of units for sale—the “iron law of prohibition” in action.

Toxicology studies have found xylazine mixed with illicit drugs starting in the early 2000s. In 2012, researchers at the University of Puerto Rico reported it was being mixed with heroin and cocaine. Lately, it has been detected more frequently throughout North America, including Canada.

The drug is a muscle relaxant and sedative often used in veterinary anesthesia. It has strong alpha-adrenergic properties, which means it causes constriction of the blood vessels. These vasoconstrictive properties dramatically reduce the blood supply to the soft tissues near the injection site, often causing the tissue to die and infected ulcerations on the users’ limbs. Sometimes the infections are severe enough to require life-saving amputation. While xylazine users can develop a physical dependency, the drug is more dangerous because the opioid overdose antidote naloxone does not reverse the respiratory depression seen with xylazine overdoses.

Many people who purchase illicit drugs on the black market might be unaware that a drug contains xylazine and may adjust their usage if they know it. Fortunately, the same Canadian company that manufactures fentanyl test strips now makes xylazine test strips. Harm reduction organizations can distribute them along with fentanyl test strips to nonmedical users in states where drug paraphernalia laws don’t stand in the way.

Xylazine has gotten a lot of media attention lately. However, as I reported last September, toxicology studies of drug overdose deaths increasingly detect a class of synthetic opioids called nitazenes, which might be up to 20 times more potent than fentanyl. (At least naloxone reverses nitazenes.)

Xylazines and nitazenes are not the final chapters of this story. The iron law of prohibition cannot be repealed. Drug cartels will keep generating new and more potent drugs, alone or in combination with existing ones, as long as policymakers refuse to end drug prohibition.

The Wall Street Journal story on xylazines quotes Erin Russell, chief of the Center for Harm Reduction Services at the Maryland Department of Health: “We can’t keep up with it, and we’re seeing the impact of it in our death data.”