Police officers, law enforcers, employers and drug testing laboratories may soon have a new tool: a breathalyzer test capable of detecting opioid drugs. Engineers and physicians from the University of California, Davis (UC Davis) have developed such a test which would lend itself to use not only for detecting illegal drug use but also monitoring patients being treated with opioids for chronic pain.
Problems with Current Opioid Diagnostic Methods
Current screening methods detect drugs by immunoassays performed on biological samples, such as urine and blood. Results are confirmed by gold-standard methods typically involving separation techniques coupled to mass spectrometry (MS). While the testing techniques provide reliable results, both specimens have sampling limitations. For one thing, drawing the samples is invasive of privacy. Urine, typically used for longer exposures, has a risk of adulteration; blood collection using plasma or serum to detect short-term consumption requires specialized personnel to collect.
The Breathalyzer Alternative
Collection of exhaled breath could be a less privacy-sensitive, non-invasive, painless and relatively easy technique. It would work on breath compounds found in either the exhaled breath aerosol (EBA) gas or exhaled breath condensate (EBC) phase. Drugs are mainly large and low-volatile molecules that can be potentially detected in EBA, e.g., exhaled microcroplets, using filters, and in EBC using a cooling system.
The New Test
The research, which is described in a paper
published in the Journal of Breath Research
published on Oct. 3, was led by a pair of UC Davis professors, Cristina Davis, chair of the Department of Mechanical and Aerospace Engineering, and Michael Schivo from the UC Davis Medical Center. The test requires subjects to breathe normally into a specialized collection device. Droplets in breath condense and are stored in a freezer for laboratory testing using mass spectrometry to identify compounds in the samples.
The researchers tested their new breathalyzer on chronic pain patients receiving infusions of morphine or hydromorphone or oral doses of oxycodone at the UC Davis Medical Center. They were then able to compare the opioid metabolites collected from the patients’ breath with both blood samples and doses given to the patients. “We can see both the original drug and metabolites in exhaled breath,” Davis noted.
The fact that researchers were able to detect, quantify and identify several opioid metabolites in EBC (and the subsequent ethanol solvent wash of the collection device) confirmed that infused opioid drugs are present in exhaled breath—although in low amounts. Since opioid drugs go through several sites of metabolism before being excreted into the lining fluid detected in exhaled breath, the concentrations of drugs are much lower than in blood for the same opioid metabolites. Even so, the researchers found “promising correlations” between concentrations in blood and breath for some of the main opioids. The implication is that even though they are diluted vis-a-vis, breath concentrations may be a reliable indicator of the presence of opioid metabolites detected by blood testing.
Still Work to Be Done
The initial results were promising. But the researchers will need more data from larger groups of patients before the new test can be fully validated. Davis is hoping to conduct the research in real-time, bedside testing.
At the same time, her laboratory is seeking to extend the test’s potential applications for detecting small amounts of chemicals through different avenues, e.g., tests diagnosing influenza in people and citrus greening disease in fruit trees.
Takeaway: Blood testing will remain the gold standard in opioid drug detection. But breathalyzer testing has the promise of offering an easier, less invasive and reliable alternative