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People taking illicit opioids on the streets are increasingly showing up to hospital emergency rooms in Pennsylvania sickened by a powerful dog and cat sedative.
Medetomidine is more potent than xylazine, another animal anesthetic that began appearing years ago in the opioid supply and challenged longstanding ways to reverse overdoses.
The newer drug is also complicating care for health care providers who work feverishly to save lives when people show up in the emergency room in crisis. The reason: There’s little research on the effects of the drug on people because there is no dose approved for humans.
“People can potentially get much, much sicker from this withdrawal syndrome than what we would expect from a more standard opioid withdrawal,” said Dr. Simon Ostrowski, an emergency medicine physician and medical toxicology fellow at UPMC.
Typically, opioid withdrawals could be managed safely at home, but withdrawals from medetomidine have regularly required treatment in intensive care units, Ostrowski said.
Medetomidine showed up in 71% of opioid samples in the first three months of the year in the state according to drug-testing organization PA Groundhogs data. At the start of last year, it wasn’t in any samples.
It's more common than xylazine and a hundred to 200 times more potent, said Dr. Daniel Teixeira da Silva, medical director for the Philadelphia Department of Health’s Division of Substance Use Prevention and Harm Reduction.
But treating withdrawals from the now-prominent sedative is complicated.
Typical drug screenings don’t catch medetomidine, so there is no widely available way to test for it in patients. This means providers can't always confirm that a patient is withdrawing from medetomidine.
Instead, they have to rely on a growing but tentative understanding of the withdrawal symptoms: rapid onset, high blood pressure and heart rate, severe nausea and vomiting, tremors and shaking.
Some patients have vomited so much their esophagus has torn or been at risk of heart attacks, strokes, and arrhythmias because of high blood pressure and heart rate, said Dr. Caitlin Couper, an inpatient addiction medicine physician at Allegheny General Hospital and West Penn Hospital.
Medetomidine has not been observed to cause the necrotic skin wounds that xylazine does.
Now, multiple patients are coming into UPMC hospitals for medetomidine withdrawal every week, Ostrowski said.
Ostrowski was the lead author on a study in a recent Centers for Disease Control and Prevention report that examined withdrawals from the drug. The report contained two studies on withdrawals in Pittsburgh and Philadelphia, respectively, and a study on overdoses in Chicago that have formed the basis of health care providers’ understanding of the sedative.
One of the patients in the Pittsburgh study had a heart attack, likely aggravated by the symptoms of medetomidine withdrawal.
Unlike an opioid withdrawal that would usually follow a relatively predictable timeline for symptoms, medetomidine withdrawals have a rapid onset of symptoms.
“The ramp up for medetomidine withdrawal is much faster, so you basically go from a zero to 100 very quickly, which is the challenge," said Dr. Sam Huo, lead author on the CDC study of medetomidine withdrawal in Philadelphia. “You might have a patient who is doing fine at hour 10, and then at hour 11, it might just all of a sudden kick in.”
But research is likely only catching the easiest cases to identify without testing: the sickest patients, Huo said.
Medetomidine is often mixed with fentanyl and xylazine, so helping patients involves managing multiple drugs. But the usual treatment for opioid withdrawal may not be the most effective with the new sedative.
The CDC studies found that one of the best ways to treat human withdrawal from it is to use dexmedetomidine, typically only used in intensive care unit treatment, not opioid treatment. Some health care providers have already started using it in suspected medetomidine withdrawals.
Prevention Point, a harm reduction nonprofit in Pittsburgh that sends drug samples for testing, has identified a shocking — and dangerous — trend: medetomidine is in most samples, but fentanyl is declining.
While this may appear to be good news, inconsistencies in the opioid supply make it even more dangerous, said Alice Bell, Prevention Point’s overdose prevention project director.
Fentanyl could be potentially lethal, even if it’s not a high dose, to someone who hasn’t taken it recently, she said.
The Philadelphia Department of Health is working to distribute medetomidine test strips and has updated guidance for using the anti-overdose drug naloxone.
So far this year 21 people have died of an opioid overdose where medetomidine was a contributing factor but not the cause, according to preliminary data provided by the state Department of Health on Tuesday. Last year that number was 69.
Since medetomidine isn’t an opioid, naloxone does not eliminate the effects of the sedative. There is no medication approved by the Food and Drug Administration to reverse medetomidine effects in humans, said Amy Nham, lead author on the CDC study of overdoses in Chicago.
Breathing and responsiveness are two ways to determine that naloxone has effectively reversed an overdose, but those who have overdosed on a mixture containing medetomidine may remain unresponsive after naloxone.
Giving more could increase the risk of precipitated withdrawal and future risk of overdose, so the Philadelphia Department of Health is emphasizing a focus on breathing, Teixeira da Silva said.
The Department of Health also put out two health advisories in 2024, notifying health care providers about the presence of medetomidine in the drug supply and about the severe withdrawal syndrome associated with its use.
