Nitazenes, a class of highly potent synthetic opioids, have also been found in the city\u2019s drug supply since at least 2022, according to the Philadelphia Department of Public Health<\/a>.\n<\/p>\n Maximized harm<\/p>\n Shaban, Morris and other experts interviewed by WHYY News said the proliferation of medetomidine and other additives reflects how drug-enforcement policies shape the illicit drug supply.\n <\/p>\n \u201cWhat we\u2019ve done, through prohibition, is maximize harm to drug users,\u201d Morris said.\n<\/p>\n He pointed to the \u201cIron Law of Prohibition<\/a>,\u201d a theory that stricter drug enforcement encourages the production and distribution of more potent substances. During the period of alcohol prohibition in the United States, for example, high-proof spirits became more common on the black market than beer, which was bulkier and more difficult to transport.\n<\/p>\n Harris said nobody would choose fentanyl over heroin, but that drug enforcement has made it impossible to find actual heroin.\n<\/p>\n Organizations that traffic illicit drugs change their formulations in response to enforcement measures, Wallach said.\n<\/p>\n In 2024, Pennsylvania classified<\/a> xylazine as a Schedule III controlled substance. That same year, medetomidine began appearing<\/a> in Philadelphia\u2019s drug supply.\n<\/p>\n \u201cWith xylazine, you used to be able to just go online and order a couple pounds of it,\u201d Wallach said. \u201cIt\u2019s a lot harder to find on the grey market now, but obviously not impossible.\u201d\n<\/p>\n Medetomidine, by comparison, remains much easier to find, particularly online, where hundreds of vendors promise to deliver it to you \u2014 and your horse \u2014 with no verification required.\n<\/p>\n But restricting dangerous drugs also involves difficult trade-offs, Perrone said.\n<\/p>\n \u201cScheduling will always cause the emergence of new drugs,\u201d she said, but leaving a drug unrestricted can create other risks.\n<\/p>\n The U.S. Drug Enforcement Administration disputes the idea that prohibition is the primary force driving changes in the illicit drug supply. Joshua Romig, assistant special agent in charge at the DEA\u2019s Philadelphia division, argued that economics play a much larger role. He pointed to the replacement of heroin by fentanyl, which he attributed to Mexican drug trafficking organizations seeking to undercut Colombian competitors.\n<\/p>\n \u201cIt was straight economics,\u201d Romig said.\n<\/p>\n Romig also rejected the suggestion that the emergence of medetomidine was a reason not to restrict xylazine.\n<\/p>\n \u201cSome ideas are better on paper. \u2026 Not scheduling xylazine [for fear of incentivizing medetomidine\u2019s introduction] would be an example,\u201d he said.\n<\/p>\n Wallach said prohibition also makes it harder for scientists to study emerging substances and understand their long-term effects.\n<\/p>\n \u201cWe have no long-term data on how medetomidine impacts human beings; it\u2019s the same for xylazine \u2013 drugs change too fast for researchers to keep up with,\u201d he said. \u201cTo work with Schedule I compounds \u2026 has been made so incredibly difficult by prohibition.\u201d\n<\/p>\n Wallach argued that regulation, rather than prohibition, would be a more effective way to reduce the harms associated with the illicit drug supply.\n<\/p>\n Steps forward<\/p>\n
\n![\"Sealed](\"https:\/\/www.newsbeep.com\/us-pa\/wp-content\/uploads\/2026\/11\/Kensington-neighborhood-resident-buuilding-AMG-110936-1024x768.jpg\")
A residential building on Kensington Avenue that\u2019s been sealed by the Philadelphia Department of Licenses and Inspections. (Andrew McGurl\/WHYY)\n<\/p>\n