Comparison of Oral Fluid and Urine for Detection of Cocaine Abuse Using Liquid Chromatography with Tandem Mass Spectrometry

Abstract

Background Requests for urine (UR) and oral fluid (OF) drug testing at our institutions are increasing. However, few studies have assessed the accuracy of each matrix using paired specimens and LC-MS/MS. We compared OF and UR for detection of cocaine (COC) abuse in addiction medicine-psychiatry (AMP) clinics. Methods We measured COC and benzoylecgonine (BZE) in OF (limit of detection (LOD) 2.0 µg/L) and BZE in UR (LOD 5 µg/L) by LC-MS/MS in 258 paired samples, and compared the two matrices when higher UR cutoffs of 25, 50, and 150 µg/L were employed. Results UR detected more COC abuse than OF at the LOD (5 µg/L). BZE was detected in 63 UR specimens and COC and/or BZE in 40 OF specimens (29 OF+UR+, 11 OF+UR-, 34 OF-UR+). UR creatinine was lower in OF+UR- specimens. COC and BZE were detected in 88% (35/40) and 75% (30/40) of OF specimens, respectively. OF was equivalent to UR at detecting COC abuse using a 25 µg/L cutoff, and detected more COC abuse than UR using 50 and 150 µg/L cutoffs. The ratio of OF COC/BZE increased with decreasing UR BZE concentrations. Conclusions We demonstrate that OF detects more COC abuse in an AMP setting when UR BZE cutoffs ≥ 50 µg/L are utilized, and that UR creatinine concentrations are significantly lower in specimens positive for COC and/or BZE in OF and negative for BZE in UR. The presence of only COC in OF and low concentrations of UR BZE likely indicates remote use of COC.

Cocaine: An Updated Overview on Chemistry, Detection, Biokinetics, and Pharmacotoxicological Aspects including Abuse Pattern

“…Recently, published research by Fernandez et al described a validated method for the detection of cocaine and several of its metabolites in 0.5 mL of urine samples, resorting to a simple derivatization step following a solid phase extraction (SPE)-the method achieved low limits of quantification from 2.5 to 10 ng/mL by using GC-MS with electron ionization [40]. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was also successfully employed to detect cocaine and BE both in urine and oral fluid [41], as it was ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) in dried blood samples [42]. Of note, cocaine in blood/plasma samples may undergo spontaneous and enzymatic hydrolysis to its metabolite BE, if the samples are not treated with a pseudocholinesterase (PChE) inhibitor, such as sodium fluoride [24].…”