title: Determination of phenyltetrahydroimidazothiazole enantiomers (Levamisole/Dexamisole) in illicit cocaine seizures and in the urine of cocaine abusers via chiral capillary gas chromatography-flame-ionization detection: clinical and forensic perspectives.
abstract: Illicit cocaine laboratories in South America have been adding phenyltetrahydroimidazothiazole enantiomers (levamisole and/or tetramisole) to refined illicit cocaine for over 8 years. A chiral capillary gas chromatographic methodology is presented for phenyltetrahydroimidazothiazole enantiomer determination in illicit cocaine samples and in the urine of cocaine abusers. Illicit cocaine samples (N = 752) and urine specimens from cocaine abusers (N = 50) that contained phenyltetrahydroimidazothiazole were analyzed for enantiomeric composition. Legitimate commercial preparations of phenyltetrahydroimidazothiazole are either 100% levamisole or a 50:50 mixture of levamisole and dexamisole (tetramisole). Specimens that contain phenyltetrahydroimidazothiazole mixtures that are other than 50:50 preparations will be enhanced in one isomer over the other, and they are referred to as either "levamisole-enhanced" or "dexamisole-enhanced". Cocaine samples were found to contain levamisole (N = 495, 66%), tetramisole (N = 143, 19%), and levamisole-enhanced enrichment (N = 114, 15%); urine specimens contained levamisole (N = 23, 46%), levamisole-enhanced enrichment (N = 10, 20%), and dexamisole-enhanced enrichment (N = 13, 26%). The toxicological and forensic aspects of these findings are discussed.
authors.affiliation: U.S. Department of Justice, Drug Enforcement Administration, Special Testing and Research Laboratory, Dulles, VA 20166-9509, USA. john.f.casale@usdoj.gov
authors.forename: John F
authors.initials: JF
authors.lastname: Casale
authors.forename: Valerie L
authors.initials: VL
authors.lastname: Colley
authors.forename: Donald F
authors.initials: DF
authors.lastname: Legatt
mesh_terms: D002849:Chromatography, Gas / Q000379:methods*; D003042:Cocaine / Q000652:urine; D019970:Cocaine-Related Disorders / Q000652:urine*; D005410:Flame Ionization / Q000379:methods*; D053593:Forensic Toxicology; D006801:Humans; D007978:Levamisole / Q000652:urine*; D012640:Seizures / Q000139:chemically induced / Q000473:pathology*; D013020:South America; D013048:Specimen Handling; D013237:Stereoisomerism; D013773:Tetramisole / Q000652:urine*
chemical_list: D007978:Levamisole; D013773:Tetramisole; D003042:Cocaine; C028075:dexamisole