Pharmacokinetics of cocaine and metabolites in human oral fluid and correlation with plasma concentrations after controlled administration

Karl B. Scheidweiler, Erin A. Kolbrich Spargo, Tamsin L. Kelly, Edward J. Cone, Allan J. Barnes, Marilyn A. Huestis

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


Oral fluid is an attractive alternative matrix for drug testing with a noninvasive and directly observed collection, but there are few controlled cocaine administration studies to guide interpretation. MATERIALS AND METHODS: While residing on a closed research unit for up to 10 weeks under constant medical supervision, 19 participants were administered 75 mg/70 kg subcutaneous cocaine and 14 received 150 mg/70 kg. The disposition of cocaine, benzoylecgonine (BE), and ecgonine methyl ester (EME) into oral fluid was determined by gas chromatography-mass spectrometry for 0.08 to 48 hours after administration. RESULTS: In oral fluid collected by citric acid candy-stimulated expectoration, cocaine first appeared in oral fluid 0.08 to 0.32 hours after dosing and was rapidly eliminated with half-lives of 1.1 to 3.8 hours. BE and EME were first detected 0.08 to 1.0 hours after dosing with longer half-lives of 3.4 to 13.8 (BE) and 2.4 to 15.5 hours (EME) (P < 0.05). Oral fluid and plasma concentrations were significantly correlated for cocaine, BE, and EME (P < 0.0001). There were no significant differences (P > 0.05) in first and last detection times with the 8-μg/L cutoff proposed by the Substance Abuse and Mental Health Services Administration or the 10-μg/L cutoff from the European initiative, Driving Under the Influence of Drugs, Alcohol and Medicines. Metabolite:cocaine ratios increased after cocaine administration, potentially helpful for interpreting time of last use. Comparison of oral fluid collection through citric acid candy-stimulated expectoration, citric acid-treated Salivette, and neutral cotton Salivette devices did not reveal significant differences between devices for areas under the curve for cocaine, BE, or EME (P > 0.05). DISCUSSION AND CONCLUSION: These results provide additional evidence for interpreting cocaine and metabolite concentrations in oral fluid and oral fluid's usefulness as an alternative matrix for drug testing.

Original languageEnglish (US)
Pages (from-to)628-637
Number of pages10
JournalTherapeutic drug monitoring
Issue number5
StatePublished - Oct 2010
Externally publishedYes


  • clinical study
  • cocaine
  • oral fluid
  • pharmacokinetics

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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