Clinical toxicology (Philadelphia, Pa.) · 2020
Tetracaine from urethral ointment causes false positive amphetamine results by immunoassay.
СтатьяНазвание и аннотация: Перевод пока не подготовлен
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Wijngaard Robin, Parra-Robert Marina, Marés Lourdes, Escalante Anna, Salgado Emilio, González-de-la-Presa Bernardino, To-Figueras Jordi, Brunet Mercè
Аннотация
BACKGROUND: Amphetamine urine drug screening by immunoassay is prone to cross-react with other compounds leading to false positive results. Tetracaine is a local anesthetic drug used in the clinical setting as an ointment during urinary catheterization. In our laboratory, tetracaine is often detected by gas chromatography-mass spectrometry in the urine of patients admitted in the emergency department with false positive amphetamine results. The objectives of this study were to investigate if there was cross-reactivity to tetracaine in an amphetamine immunoassay and to retrospectively evaluate the potential contribution of tetracaine to false positive amphetamine results.
METHODS: An interference study was conducted using negative urine samples spiked with increasing concentrations of tetracaine hydrochloride and analyzed with the CEDIA Amphetamine/Ecstasy immunoassay. Retrospectively, urine samples of patients which yielded positive amphetamine immunoassay results and were analyzed by gas chromatography-mass spectrometry were reviewed (n = 417). The presence of tetracaine and/or other drugs by gas chromatography-mass spectrometry were gathered.
RESULTS: Tetracaine caused false positive amphetamine results by immunoassay (cut-off 1000 µg/L) with a concentration of above 40 mg/L. Retrospective analysis of all positive amphetamine immunoassay samples showed that in 45 out of the 417 (10.8%) urine samples no amphetamine-like derivative was identified by gas chromatography - mass spectrometry. In 37 out of 45 (82.2%) of these false positive cases tetracaine was detected, of whom 59.5% (22/37) had an estimated tetracaine concentration of ≥40 mg/L.
CONCLUSIONS: This study confirmed the interference of tetracaine in the CEDIA Amphetamine/Ecstasy immunoassay and that tetracaine may have contributed to around 80% of the false positive amphetamine cases in the urine samples of patients admitted to the emergency department at our institution.
METHODS: An interference study was conducted using negative urine samples spiked with increasing concentrations of tetracaine hydrochloride and analyzed with the CEDIA Amphetamine/Ecstasy immunoassay. Retrospectively, urine samples of patients which yielded positive amphetamine immunoassay results and were analyzed by gas chromatography-mass spectrometry were reviewed (n = 417). The presence of tetracaine and/or other drugs by gas chromatography-mass spectrometry were gathered.
RESULTS: Tetracaine caused false positive amphetamine results by immunoassay (cut-off 1000 µg/L) with a concentration of above 40 mg/L. Retrospective analysis of all positive amphetamine immunoassay samples showed that in 45 out of the 417 (10.8%) urine samples no amphetamine-like derivative was identified by gas chromatography - mass spectrometry. In 37 out of 45 (82.2%) of these false positive cases tetracaine was detected, of whom 59.5% (22/37) had an estimated tetracaine concentration of ≥40 mg/L.
CONCLUSIONS: This study confirmed the interference of tetracaine in the CEDIA Amphetamine/Ecstasy immunoassay and that tetracaine may have contributed to around 80% of the false positive amphetamine cases in the urine samples of patients admitted to the emergency department at our institution.