title: Detection of levamisole exposure in cocaine users by liquid chromatography-tandem mass spectrometry.
abstract: Levamisole, a veterinary antihelminthic, was recently recognized as an adulterant in cocaine and is known to cause severe adverse reactions in some cocaine users. Because of the health concerns involving levamisole-adulterated cocaine, we developed a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the detection of levamisole in urine. This method was used to determine the prevalence of levamisole in cocaine-positive patient samples. All cocaine-positive urine samples that were sent to the San Francisco General Hospital Clinical Laboratory were tested for levamisole for one month. For LC, an Agilent 1200 series was used with a C(18) column and a gradient of mobile phase A (0.05% formic acid) and B (acetonitrile/methanol). Detection was carried out with an Applied Biosystems QTRAP(®) LC-MS-MS. The levamisole LC-MS-MS method was linear over the range of 5-2500 ng/mL (r > 0.996). Interassay and intraassay CVs were < 6%. The lower limit of detection for levamisole was 0.5 ng/mL. Out of 949 total urine drug screens, 20% were positive for benzoylecgonine, and of those, 88% were positive for levamisole. The high prevalence of levamisole-adulterated cocaine and potential toxicity in cocaine users is a serious public health concern. These findings validate the utility of an LC-MS-MS method for the detection of levamisole.
authors: Department of Laboratory Medicine, University of California San Francisco, San Francisco, California 94110, USA. kara.lynch@ucsf.edu
authors: Kara L
authors: KL
authors: Lynch
authors: Stephen S
authors: SS
authors: Dominy
authors: Jonathan
authors: J
authors: Graf
authors: Alexander H
authors: AH
authors: Kral
mesh_terms: D000328:Adult; D000969:Antinematodal Agents / Q000009:adverse effects / Q000652:urine*; D002853:Chromatography, Liquid; D019970:Cocaine-Related Disorders / Q000453:epidemiology / Q000652:urine*; D004340:Drug Contamination / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007978:Levamisole / Q000009:adverse effects / Q000652:urine*; D008297:Male; D008875:Middle Aged; D015813:Substance Abuse Detection; D053719:Tandem Mass Spectrometry
chemical_list: D000969:Antinematodal Agents; D007978:Levamisole