title: Metabolism of levamisole and kinetics of levamisole and aminorex in urine by means of LC-QTOF-HRMS and LC-QqQ-MS.
abstract: The antihelminthic drug Levamisole can enhance cocaine effects by conversion into the amphetamine-like drug aminorex. We describe an LC-MS method for the determination of levamisole and its metabolite aminorex in human urine. Selectivity is given, calibration curves were linear within the calibration range 2.5-250 ng/mL; limits of the method were LoD 0.51 ng/mL, LoQ 1.02 ng/mL for levamisole and LoD 0.65 ng/mL, LoQ 0.76 ng/mL for aminorex. Precision data was in accordance with the guidelines (intraday precision for aminorex ranged between 5.75 and 11.0 % for levamisole between 8.36 and 10.9 %; interday precision for levamisole 10.9-16.9 % and for aminorex 7.64-12.7 %; accuracy data for levamisole -1.96 to -14.3 % and for aminorex-11.9 to-18.5 %). The validated method was successfully applied to study the urinary excretion of levamisole after the administration of 100 mg of levamisole orally. Levamisole and aminorex could be detected in post-administration urine samples. Levamisole could be detected up to 39 h after ingestion, while aminorex was detectable up to 54 h. Maximum aminorex concentrations were 45 ng/mL urine. Further metabolites of levamisole after oral ingestion by means of liquid chromatography hybrid quadrupole time-of-flight high-resolution mass spectrometry (LC-QTOF-HRMS) were identified. Only 0.5 % of the ingested drug was quantified as unchanged levamisole in urine. Besides aminorex, five isomers of aminorex and 4 hydroxy-metabolites of aminorex or its isomers were found. Furthermore, levamisole is also hydroxylated and eliminated free or conjugated with sulfate or glucuronide into urine.
authors: Institute of Forensic Medicine, University of Bonn, Bonn, Germany. cohess@uni-bonn.de
authors: Cornelius
authors: C
authors: Hess
authors: Natalie
authors: N
authors: Ritke
authors: Sebastian
authors: S
authors: Broecker
authors: Burkhard
authors: B
authors: Madea
authors: Frank
authors: F
authors: Musshoff
mesh_terms: D000635:Aminorex / Q000378:metabolism / Q000652:urine*; D000871:Anthelmintics / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine*; D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D007978:Levamisole / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine*; D057230:Limit of Detection; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000871:Anthelmintics; D007978:Levamisole; D000635:Aminorex