Commonly Prescribed Medications Often Trigger ‘False Positive’ Results

By Paul Armentano    August 2010

Prescribed medications commonly trigger ‘false positive’ results for illicit substances on urine drug screens, according to a review published in the August 15th edition of the Journal of the American Society of Health-Systems Pharmacists.

Investigators at the University of Oklahoma, College of Pharmacy conducted a comprehensive literature review assessing the likelihood of ‘false positive’ drug test results for 116 separate medications.

“Reports of false positive UDS (urine drug screens) result were found for 25 (21.5 percent) of the 116 formulary medications,” authors found.

Prescribed medications were most likely to yield false positive results for amphetamine or methamphetamine, the study reported.

Medications were far less likely to positive for marijuana. Nevertheless, researchers concluded that “acute or chronic ibuprofen use” was occasionally associated with false positive cannabinoid results. However, these results were only documented on the enzyme-mediated immunoassay (EMIT) test.

Authors concluded: “A number of routinely prescribed medications have been associated with triggering false positive UDS results. Verification of the test results with a very different screening test or additional analytical tests should be performed to avoid adverse consequences for patients.”

Full text of the study, “Commonly prescribed medications and potential false positive urine drug screens,” appears in the Journal of the American¬† Society of Health-Systems Pharmacists.

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