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

• Published in: Journal of analytical toxicology Vol. 36; no. 2; pp. 130 - 135
• Main Authors: Casale, John F., Colley, Valerie L., LeGatt, Donald F.
• Format: Journal Article
• Language: English
• Published: Niles, IL Oxford University Press 01.03.2012; Preston Publications
• Subjects: Biological and medical sciences; Chromatography, Gas - methods; Cocaine; Cocaine - urine; Cocaine-Related Disorders - urine; Drug addictions; Enantiomers; Flame Ionization - methods; Forensic science; Forensic Toxicology; Humans; Isomers; levamisole; Levamisole - urine; Medical sciences; Seizures; Seizures - chemically induced; Seizures - pathology; South America; Specimen Handling; Stereoisomerism; Tetramisole - urine; Toxicology; Urine; South America; Biological fluid; Chemical analysis; Anthelmintic; Separation; Psychotropic; Flame ionization detector; Ester; Enantiomer; Imidazothiazole derivatives; Antidepressant agent; Drug of abuse; Quantitative analysis; Human; Urine; Drug addiction; CNS stimulant; Levamisole; Chiral stationary phase; Tropane derivatives; Local anesthetic; Immunomodulator; Gas chromatography; Cyclodextrin; Dexamisole; Immunostimulant agent; Optical resolution; Parasiticide; Cocaine; Inclusion compound
• ISSN: 0146-4760; 1945-2403
• DOI: 10.1093/jat/bkr025

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.