A Case of Esmolol-Induced False-Positive Amphetamine Urine Drug Test

Abstract

False-positive urine drug screens can occur and lead to implicit bias. Confirmatory testing with gas chromatography/mass spectrometry can be performed. A morbidly obese patient with newly diagnosed atrial fibrillation spent multiple days in the cardiac intensive care unit (ICU) due to a false-positive test for methamphetamine. The patient was planned to undergo direct cardioversion with conscious-sedation anesthesia. His care was delayed because anesthesia was not comfortable administering sedatives in the setting of a positive urine drug screen for presumed methamphetamine use. Knowing that esmolol can cause a false positive on urine drug screen is imperative for delivering the best patient-centered care.

Guilty or not guilty? — False positive results of common medicines in drug tests: review and practical guide

“…Esmolol has also been reported to cause F/P results in AMP assays. This finding was described in a case report involving a 27-year-old male patient who underwent esmolol treatment and tested positive for amphetamines in a UDS, despite denying any use of tobacco or recreational drugs [23]. The laboratory findings, which investigate the cross-reactivity of numerous substances, provide additional validation for the potential occurrence of positive results for both esmolol and esmolol acid [15].…”

“…Esmolol Homogeneous enzyme immunoassay Abbott MULTIGENT® (500 μg/L) 237,300 μg/L 2 [15] [22] [23] Esmolol acid Homogeneous enzyme immunoassay Abbott MULTIGENT® (500 μg/L) 446,400 μg/L 2 [15] Famprofazone CEDIA immunoassay (N.M.) 100 mg -6 h before test 1 [24] Fenfluramine Amphetamine immunoassay screens (N.M.) [20] Fenofibrate amphetamine/MDMA CEDIA (1000 μg/L) daily dose of 267 mg 1 [25]…”