Detectability of fentanyl and designer fentanyls in urine by 3 commercial fentanyl immunoassays

Abstract

In recent times, structural variants of fentanyl (designer fentanyls) have appeared on the recreational drug market for new psychoactive substances (NPS). These potent opioids have caused harmful intoxications and increased opioid-related mortality in many countries. This work evaluated 3 commercial immunoassays for fentanyl screening in urine and investigated whether they are useful also for screening of designer fentanyls. The assays examined were the Thermo DRI® Fentanyl Enzyme Immunoassay, the ARK™ Fentanyl Assay homogeneous enzyme immunoassay, and the Immunalysis® Fentanyl Urine SEFRIA™ Drug Screening Kit. A liquid chromatography-high-resolution mass spectrometry method was used as reference. The DRI fentanyl immunoassay generated somewhat higher assay imprecision values (%CV) compared with the ARK™ and SEFRIA™ assays, but all assays showed %CV values acceptable for routine use. The 3 assays showed overall good detectability (33%-95% cross-reactivity) for blank urine samples spiked with acetylfentanyl, acrylfentanyl, butyrfentanyl, 4-chloroisobutyrfentanyl, 4-fluorobutyrfentanyl, 4-fluorofentanyl, 4-fluoroisobutyrfentnyl, isobutyrfentanyl, methoxyacetylfentanyl, or tetrahydrofuranfentanyl, whereas 4-methoxybutyrfentanyl (all assays) and 2-fluorofentanyl (DRI assay) showed low cross-reactivity. A good detectability of designer fentanyls was confirmed in urine samples from authentic acute intoxications. In conclusion, the present results demonstrate that the urinary fentanyl immunoassays are generally useful also for preliminary screening of fentanyl analogs sold as NPS. When the SEFRIA™ assay was applied for testing of 980 urine samples from patients treated for drug dependence in Sweden, only 1 sample was confirmed positive for fentanyl.

Drug trends and harm related to new psychoactive substances (NPS) in Sweden from 2010 to 2016: Experiences from the STRIDA project

“…For example, analogues of fentanyl have required immediate medical support but also caused many fatalities due to the potentially life-threatening symptoms of opioid overdose [10][11][12], but unexpected acute and late toxic effects have also been reported for several other novel substances [13][14][15]. Furthermore, there are analytical problems to confirm NPS exposure, because the new substances are often undetectable by conventional toxicology tests, or may generate false-positive screening results for classical illicit drugs due to close structural similarities [16][17][18].…”

Novel synthetic opioids – toxicological aspects and analysis

“…The work of Helander et al. [99] describes the real samples as coming from cases of intoxication, not clarifying the state of the patients. The work of Sofalvi et al.…”

Interpretation and Utility of Drug of Abuse Screening Immunoassays: Insights From Laboratory Drug Testing Proficiency Surveys

“…As an example, the performance of fentanyl immunoassays on the UDS survey is consistent with published literature evaluating the analytical performance of fentanyl immunoassays. [25][26][27][28] However, it is worth noting key details about the survey structure that distinguish UDS samples from true patient specimens. The first is that the survey generally challenges high concentrations of the targeted drugs, which might be unrealistic, especially for high-potency compounds.…”

“…source of screen-positive results that are negative in traditional confirmation tests. 25,29,30 Laboratories should be familiar with the cross-reactivity profile of their immunoassays, including the published literature, which often characterizes drugs not included in typical manufacturer studies, such as drug metabolites or designer drugs of abuse. 31 The variability of cross-reactivity within immunoassays targeting a drug class was highlighted by the performance of laboratories testing using various amphetamine-related immunoassays when challenged by MDMA.…”