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"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..."
Forensic Sci Int. 2007 May 2;
Excretion of Delta(9)-tetrahydrocannabinol in
sweat.
Huestis MA,
Scheidweiler KB,
Saito T,
Fortner N,
Abraham T,
Gustafson RA,
Smith ML.
Chemistry and Drug Metabolism, Intramural
Research Program, National
Institute on Drug Abuse, National Institutes of
Health, 5500 Nathan Shock
Drive, Baltimore, MD 21224, USA.
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((R))
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 0.4ng 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 1ng THC/patch. Mean+/-S.E.M. THC
concentrations were 3.85+/-0.86ng
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 14.8mg 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
6.1mug/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
14.8mg THC daily does not produce a THC positive
sweat patch test.
PMID: 17481836 [PubMed - as supplied by
publisher]
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