A state can also list the drug. On Tuesday, Gov. Josh Shapiro of Pennsylvania, where the Philadelphia neighborhood of Kensington is ground zero for tranq dope, announced that his administration was doing so.
A spokesman for the governor, Manuel Bonder, said Mr. Shapiro had decided to move ahead with the designation “rather than wait for any future possibilities in D.C.”
Xylazine was approved by the F.D.A. for veterinary procedures in 1972. Since then, it has been used for procedures on sheep, deer, elk and even cats and dogs, as well as on horses and cattle. Earlier trials in humans had been shut down because the drug led to respiratory depression, so manufacturers never sought approval for human use. Until now, there has been insufficient incentive to research its impact on people. Its causal relationship to the flesh wounds that can result from its use is not understood. And unlike the protocols for opioids, those for reversing tranq dope withdrawal or managing rehabilitation have not been standardized.
Last month, a bipartisan bill introduced in both chambers of Congress by members from rural states — including Nevada, Iowa, New Hampshire, California, Florida, Texas and Colorado — offered a compromise. Rather than listing xylazine as a controlled substance, the bill proposes that a person who employs it for “illicit” purposes — sales or distribution for human use — would face the same penalties as if it were listed as a Schedule III drug, including fines up to $500,000 and a first-offense sentence of up to 10 years in prison.
Controlled substances are classified according to medical need and potential for abuse and addiction. Schedule III includes buprenorphine, the medication used to treat opioid use disorder. By comparison, Schedule I includes heroin and L.S.D. Schedule II includes oxycodone and fentanyl, which can be prescribed for pain.