title: Cocaine and metabolite elimination patterns in chronic cocaine users during cessation: plasma and saliva analysis.
abstract: Several reports suggest a prolonged elimination of cocaine and metabolites after chronic use compared with single or occasional use. This study was designed to measure the half-lives of cocaine in plasma and saliva of individuals who consumed cocaine on a frequent basis. The disposition and elimination patterns of cocaine and metabolites in the body fluids of chronic high-dose cocaine users during acute cessation of use were investigated. Plasma and saliva specimens were collected over a 12-h period during cessation and analyzed by gas chromatography-mass spectrometry. Pharmacokinetic parameters were derived by noncompartmental analysis of plasma and saliva data. Results indicated a cocaine terminal T(1/2) of 3.8 h in plasma and 7.9 h in saliva. The terminal T(1/2) of benzoylecgonine was 6.6 h in plasma and 9.2 h in saliva. Compared with prior studies of acute low-dose cocaine administration, these findings suggest that cocaine's half-life is longer in active street users than in occasional users though the half-life of its main metabolite benzoylecgonine remains similar (as do cocaine saliva-to-plasma ratios). Thus, regular use of cocaine appears to alter the disposition and elimination of cocaine when compared to single or occasional use.
authors.affiliation: Clinical Pharmacology and Therapeutics Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA.
authors.forename: E T
authors.initials: ET
authors.lastname: Moolchan
authors.forename: E J
authors.initials: EJ
authors.lastname: Cone
authors.forename: A
authors.initials: A
authors.lastname: Wstadik
authors.forename: M A
authors.initials: MA
authors.lastname: Huestis
authors.forename: K L
authors.initials: KL
authors.lastname: Preston
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003042:Cocaine / Q000032:analysis / Q000493:pharmacokinetics*; D019970:Cocaine-Related Disorders / Q000378:metabolism* / Q000534:rehabilitation; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000737:chemistry*
chemical_list: D003042:Cocaine