A Cross-Reactivity of Fenofibric Acid With MDMA DRI Assay

Abstract

Fenofibrate's interference with MDMA immunoassay was confirmed. Fenofibrate being widely prescribed, physicians had to be alerted that this treatment could lead to false-positive results.

False‐positive urine screen test for MDMA in a patient exposed to mebeverine

“…Concerning MDMA/ecstasy, which is structurally related to amphetamines, cross-reactions in immunoassays and false-positive MDMA tests have been reported for trazodone, metoprolol and the fenofibrate metabolite, fenofibric acid. 6,9,10 In our case, the depressed level of consciousness was attributed to the long-acting benzodiazepine used by the patient, and no legal action was taken towards the patient's son. However, this situation could have evolved much differently.…”

Variability amongst urine toxicology amphetamine readings with concurrent administration of fenofibrate

“…Laboratory A uses the CEDIA UDS for amphetamines which has known cross-reactivity with fenofibrate and its metabolites. 8,10,11 The product information supplied with the test kit does not indicate that fenofibrate may lead to false-positive results, 3 although a document from the manufacturer (identified in an online search) indicated that a metabolite of fenofibrate may lead to false-positive results. 12 Laboratory B used a different method, the Roche ONLINE Amphetamine Immunoassay (Roche Diagnostic Systems, Inc., Somerville, NJ), for which false-positive results with fenofibrate have not been described.…”

“…It is believed that fenofibrate, or a metabolite of it, has a molecular structure bearing similarity to amphetamine which may produce false-positive UDS readings. [8][9][10][11] In these research articles, mass spectrometry was used as a gold standard to confirm or refute presumptive positive results based upon the initial UDS.…”