Amy Carpenter
February 2024—Xylazine prevalence, lab-developed testing, and new technology are converging at Yale New Haven Health in a way that gives rise to questions, worry, and new hope for faster drug testing.
Yale’s emergency department physicians alerted the clinical chemistry laboratory in mid-2023 of the need to develop testing for xylazine, a nonopiate sedative, analgesic, and muscle relaxant authorized for veterinary use. It is reported as an adulterant in illicit drug mixtures and has been detected in an increasing number of overdose deaths.
The laboratory is still in the evaluation phase of its laboratory-developed mass spectrometry test and sending out one to two of the ED’s samples weekly for xylazine testing. “Eventually when we go live with our test, then we’ll be able to offer it in-house,” says Joe El-Khoury, PhD, D(ABCC), director of the clinical chemistry laboratory, Yale New Haven Health, and associate professor of laboratory medicine, Yale University School of Medicine.
For now, he says, “We are shocked. We just started preliminary testing and we’re finding a significantly higher number of positives than we expected.” And this when all he and his colleagues were setting out to do was to determine: “Do we even see it?”
Of the 60 to 80 samples they had tested as part of the validation process by mid-December, 30 to 40 percent of those that were positive for fentanyl, cocaine, or heroin had detectable levels of xylazine, he says.
His team had begun its validation by pulling patient samples positive for fentanyl because the CDC reported detectable xylazine in about 30 percent of fentanyl overdoses, he says.
“Then cocaine came to our attention. They’re saying they’re seeing it there too, so we started pulling those. Heroin is another one”—so they pulled those samples. “We’re seeing 30 to 40 percent showing up positive in those drug categories.”
Now that he and his colleagues know it’s there, and in high numbers, the question is how clinically relevant it is. “We’re in the process of trying to figure out what is the clinical impact of this,” Dr. El-Khoury says, noting they have their institutional review board’s approval to review the patients’ medical charts to determine their clinical status. In December they were beginning to do so.
“There are definitely two camps,” he says. “The general perception has been that it really won’t change clinical management if we know there’s xylazine, but it will help in terms of surveillance and knowing how much of an issue this is.” Thus, some find it acceptable to continue to send the samples out for testing and wait three to five days for results. “Others were banging the drums, saying, ‘We need this in-house.’ So we moved to meet that need.”
He’s in the I-don’t-know camp, he says. “We’re building this test to study it and figure out—is it useful or is it not?” He is skeptical of an insistence on the need for a xylazine test, he says, because there is no treatment except to manage the patient’s symptoms, usually with naloxone if fentanyl co-ingestion is suspected, but naloxone cannot reverse xylazine intoxication. “Most are simply giving Narcan and then continue to give Narcan until the patient is revived.”
In Yale New Haven’s clinical chemistry laboratory, a 120-sample comparison is underway now with another laboratory that set up testing also. “That is the final piece of going live” with the laboratory-developed test, Dr. El-Khoury says.
Which is where the worry comes in. “Today it’s xylazine. Tomorrow it’s who knows what? It was fentanyl yesterday, and the day before it was synthetic cannabinoids. The only way to respond to this is by doing laboratory-developed tests, but with the FDA cracking down on that, that’s going to be a problem,” Dr. El-Khoury says.
Neither he nor anyone else knows how much time FDA review will take, if it is ultimately required, “but that adds that much time to the timeline to offer these tests,” he says. Even now, he adds, “By the time we’ve added xylazine, it’s like we’ve already moved on” to the next drug.
“We’re not able to help our ED physicians as well as we’d like because of the lack of availability of FDA-approved tests” for new drugs, “and mass spec sadly isn’t fast enough.”
Speed is what Dr. El-Khoury and colleagues are working on now with a technology called DART mass spectrometry.
Though he questions the need for a rapid xylazine test result, he acknowledges that ED physicians may need it at some point, and if there is no immunoassay (Randox’s ELISA is not suited to a rapid-response lab, he notes), the question is whether mass spectrometry can be made available to them more rapidly. For that, he and his colleagues are exploring DART mass spectrometry (direct analysis in real time mass spectrometry), which requires no chromatography, a time-consuming step. “We can almost run in real time patient samples on mass spec with minimal chromatography,” he says.
DART-MS has been applied successfully in other industries such as food analysis, he says, “but we are the first to evaluate its utility for rapid urine toxicological analysis.”
His group’s unpublished data (a paper is in preparation) suggests that it works well for specific drugs where chromatographic separation is not essential. “For some things it works, for others it doesn’t,” he says. It works for fentanyl and buprenorphine; it hasn’t yet been tested on xylazine.
IonSense is the developer of the DART-MS Dr. El-Khoury and colleagues are evaluating. Bruker acquired IonSense in 2022. Ibrahim Choucair, PhD, a former clinical chemistry fellow at Yale New Haven Health, presented at the 2022 Mass Spectrometry and Advances in the Clinical Lab meeting, where he reported their development of a fast DART-MS method for the qualitative analysis of 15 opioids in less than 10 seconds and a limit of detection for all compounds below 10 ng/mL in pure standards. “The new method promises to cut turnaround time from days to minutes, and with the high sensitivity and specificity of mass spectrometry technology, we believe that it may one day replace or supplement immunoassays as a drug screening tool,” reads Dr. Choucair’s abstract (https://bit.ly/3vyCSkw). Dr. Choucair is now assistant professor, Department of Pathology and Laboratory Medicine, University of Kentucky College of Medicine.
DART-MS “allows you to load a urine sample on a strip,” Dr. El-Khoury says, “and the DART technology is essentially blowing through that sample on the strip to directly inject it into the mass spectrometry. So there is no chromatography. The beauty of it is it’s fast because as soon as you load the sample, you get a result typically within seconds.” Methods with chromatography for other drugs need an additional 10 to 15 minutes for each sample, Dr. El-Khoury says, in addition to time to run calibrators and quality control material, so the entire process could take hours by comparison.
DART-MS will not work for drugs with isobars, which are compounds of the same mass that can interfere. Examples are morphine and hydromorphone. “They’re the same molecular weight,” he says. “You need chromatographic separation so they don’t cross-react and are detected by the same channel.”
DART-MS doesn’t separate channels as well as conventional mass spectrometry, though he’s seen no problems with drugs such as fentanyl, norfentanyl, or buprenorphine. “I’m looking at these areas where we don’t have methods, like xylazine, where I can build something for it and then be able to run it and provide it to the ED.”
DART-MS is still firmly in the research realm, he emphasizes. “I don’t want to oversell the technology. I’m just saying we’re thinking ahead”—about how to stay ahead of the drug use changes.
Another reason for hope: automated mass spectrometry.
Roche unveiled at the EuroMedLab 2023 meeting in Rome a prototype for its Cobas Mass Spec. “They have a limited panel that includes drugs of abuse,” Dr. El-Khoury says. “In theory, in the next five years if that comes through to the United States and gets FDA approval, we can be talking about real-time mass spectrometry happening on the automated line.” Roche calls it “an entirely automated clinical mass spectrometry solution for the routine lab” and says it has plans for more than 60 analytes.
Roche’s system is a targeted approach, Dr. El-Khoury points out. “It won’t help you find a new drug on the market,” because mass spectrometry wasn’t developed to see it. Advanced toxicology laboratories such as NMS Labs use time-of-flight mass spectrometry, which can be designed to be nontargeted, pick up any signal, and crossmatch it to a library of thousands of compounds that can be regularly updated to stay relevant.
Currently, laboratories “are still almost always behind,” he says.
“The targeted approach will not help us get faster at detecting new agents.” As laboratories, “we will still need to be rapid and respond by building or bringing in methods that allow us to do new drug testing much faster than what we currently do with the FDA-approved immunoassays.”
Amy Carpenter is CAP TODAY senior editor.