TIME-COURSE OF COCAINE IN RABBIT HAIR

The accurate interpretation of analytical results from hair testing fo r drugs of abuse continues to be a complex and difficult problem since many questions still remain unanswered. In this paper an animal model was developed to ascertain the time course for the appearance and dis appearance of cocaine and its metabolite benzoylecgonine (BE) in hair. Female Fauve Bourgogne red-haired rabbits (n = 6) were intraperitonea lly administered a single dose of cocaine at 5 mg/kg. Animal hair was shaved just before drug administration and the newly grown back hair w as subsequently shaved and collected daily over a period of two weeks. Samples were analyzed for cocaine and BE by gas chromatography-mass s pectrometry (GC-MS). The profiles were quite similar for parent drug a nd metabolite. Cocaine and BE appeared in the first sampling (day 1), with peak concentration appearing that same day: 1.01 ng/mg and 0.51 n g/mg for cocaine and BE, respectively. Levels declined rapidly on day 2, remaining detectable for ten days after drug administration. This s tudy demonstrates that the initial incorporation of cocaine compounds in rabbit hair is very rapid (24 h). A small fraction of the drug is d etected ten days after exposure, at a time when concentrations in othe r biological specimens (blood or urine) are not detectable. (C) 1997 E lsevier Science Ireland Ltd.