Another new synthetic drug that is used as a veterinary tranquilizer, medetomidine, showed up in the autopsy of a recent overdose victim in San Francisco, though it does not yet appear prevalent in the local drug supply.

A powerful street drug that began showing up alongside "tranq" (xylazine) and fentanyl in Philadelphia and other cities last year, medetomidine or "rhino tranq," may be making its way west. And the SF Department of Public Health issued a statement this week about a recent local overdose death in which this drug was involved, calling the development "concerning."

As the Chronicle reports, the Office of the Chief Medical Examiner confirmed that a 46-year-old woman had died in the city in February, and she had a mixture of drugs in her system including fentanyl, medetomidine, and benzodiazepines (i.e. lorazepam and the like).

The first Chronicle report about medetomidine came last May, just as warnings about the drug were being issued in East Coast cities. The drug, used for animal anesthesia, can cause "heightened sedation" and "profound bradycardia" in humans, and it appears to have entered certain drug supplies in mixtures that also contain fentanyl and xylazine.

A panic around "tranq" or xylazine also spread in the last couple of years, however the SF Department of Public Health suggests that it still never really caught on in SF the way it did in Philadelphia and elsewhere. The drug is linked with severe skin ulcers, which have led to tragic effects on the drug-user population in multiple cities, including amputated extremities and limbs.

It's not clear if medetomidine has any similar effects when it comes to skin lesions, but similar to xylazine, it is known to cause "harmful and abrupt” withdrawal symptoms in combination with fentanyl or heroin.

A notice dated May 13, 2024 from the Philadelphia Department of Public Health noted that overdose victims seen in the city where medetomidine was a factor exhibited extreme hypertension, bradycardia, and "prolonged sedation that is not reversed by naloxone."

The notice also explains that medetomidine has only been found in samples along with fentanyl, and that it is a synthetic alpha-2 adrenoreceptor agonist sedative that has never been approved for human use. "In human medicine, medetomidine is most similar to dexmedetomidine (Precedex®) and clonidine," the health department explains.

The Chronicle reports via Alex Krotulski, director of the Center for Forensic Science Research and Education, that xylazine may be on the way out in the street-drug trade, and that the far more potent medetomidine is largely replacing it in the supply.

The February death in San Francisco comes at a moment when overdose deaths appear to be ticking up, after a year in which they were trending downward. 2024 actually saw the fewest overdose deaths in the city in five years, marking a potential turning point in the fentanyl crisis, which began about five or six years back.

The decrease in overdose deaths has largely been attributed to substantial increases in the distribution of methadone and buprenorphine to treat opioid addiction, as well as the widespread availability of naloxone, used to reverse overdoses.

Also, some health experts have surmised that the drug-user population may be getting more spooked about overdoses, and many of those who were most prone to having them have either quit using or have died.