Excretion of Delta9-tetrahydrocannabinol in sweat

Forensic Sci Int. 2008 Jan 30;174(2-3):173-7. doi: 10.1016/j.forsciint.2007.04.002. Epub 2007 May 3.

Abstract

Sweat testing is a noninvasive technique for monitoring drug exposure over a 7-day period in treatment, criminal justice, and employment settings. We evaluated Delta(9)-tetrahydrocannabinol (THC) excretion in 11 daily cannabis users after cessation of drug use. PharmChek sweat patches worn for 7 days were analyzed for THC by gas chromatography-mass spectrometry (GC/MS). The limit of quantification (LOQ) for the method was 0.4 ng THC/patch. Sweat patches worn the first week of continuously monitored abstinence had THC above the United States Substance Abuse Mental Health Services Administration's proposed cutoff concentration for federal workplace testing of 1 ng THC/patch. Mean+/-S.E.M. THC concentrations were 3.85+/-0.86 ng THC/patch. Eight of 11 subjects had negative patches the second week and one produced THC positive patches for 4 weeks of monitored abstinence. We also tested daily and weekly sweat patches from seven subjects who were administered oral doses of up to 14.8 mg THC/day for five consecutive days. In this oral THC administration study, no daily or weekly patches had THC above the LOQ; concurrent plasma THC concentrations were all less than 6.1 microg/L. In conclusion, using proposed federal cutoff concentrations, most daily cannabis users will have a positive sweat patch in the first week after ceasing drug use and a negative patch after subsequent weeks, although patches may remain positive for 4 weeks or more. Oral ingestion of up to 14.8 mg THC daily does not produce a THC positive sweat patch test.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Double-Blind Method
  • Dronabinol / administration & dosage
  • Dronabinol / analysis*
  • Female
  • Forensic Toxicology
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Male
  • Marijuana Abuse / diagnosis*
  • Psychotropic Drugs / administration & dosage
  • Psychotropic Drugs / analysis*
  • Substance Abuse Detection
  • Sweat / chemistry*
  • Time Factors

Substances

  • Psychotropic Drugs
  • Dronabinol