Abstract: Objective A rapid and sensitive method was developed for the simultaneous identification and quantitation of ketamine and its two major metabolites , norketamine(NK) and dehydronorketamine(DHNK) in hair. The characteristics of K incorporation into the hair was elucidated. Methods Cavies were administrated intraperitoneally according to high, medium and low doses and hair segments with different colors were shaved. Human hair samples were collected from K abusers in the entertainment places. After decontamination, incubated and extracted, drugs were analyzed by GC/MS-SIM. Results There was an obvious correlation between the concentration of ketamine in experimental cavy hair and the dosege. The concentration of ketamine in hair increased with the melanin amount in hair in the order of white, brown and black. DHNK was only detected in high dose cavy hair; the ratio of ketamine to NK was between 2.33 to 12.94. Ketamine and NK were present in all the black hair samples, but DHNK was not detected. The concentration of metabolites in cavy hair was significantly higher than that of human. Conclusion Our results suggest that there is a close correlation between the affinity of drug to melanin in hair and the lipophilicity of the drug. However, there is a difference in drug metabolism and the difficulty in drug incorporating into hair between human and animal. This method can be used in the analysis of ketamine in hair in forensic toxicology.

Key words: ketamine, metabolites, doses, hair, colors