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TABLE 3.1 Psychoactive Doses of THC in Humans

Investigators

THC Delivery
System

THC Dose
Administered

Resulting
Plasma Concentrations
of THC

Subjects' Reactions

Heishman and
co-workers
(1990)62a

One 2.75%
THC
cigarette
smoked

0.32 mg/kga

50-100 ng/ml

At higher level, subjects
felt 100% "high" and
psychomotor
performance
was decreased;
at 50 ng/ml, subjects
felt about 50%, "high"

Kelly and
co-workers
(1993)85

1-g marijuana
cigarette
smoked (2% or
3.5% THC)

0.25-0.50
mg/kg"

Not measured

Enough to feel
psychological effects
of THC

Ohlsson and
co-workers
(1980)118

19-mg THC
cigarette
smoked
(about 1.9'%
THC)

About 0.22
mg/kg1

100 ng/ml

Subjects felt "high"

 

5 mg of THC
injected
intravenously

About 0.06
mg/kgb

100 ng/ml

Subjects felt "high"

 

Chocolate chip
cookie
containing
20 mg of THC

About 0.24
mg/kg

8 ng/ml

Subjects rated "high"
as only about 40"%,

Lindgren and
co-workers
(1981)95

19-mg THC
cigarette
smoked to
"desired high"

12 mg smoked
(7 mg
remained
in cigarette
butt)

85 ng/ml
after 3 min.,
35 ng/ml
after 15 min.

Subjects felt "high"
after 3 min., and
maximally high
after 10-20 min.
(average self-ratings of
5.5 on 10-point scale)

 

5 mg of THC
injected
intravenously

0.06 mg/kg'

300 ng/ml
after 3 min.,
65 ng/ml
after 15 min.

Subjects felt maximally
"high" after 10 min.
(average self ratings of
7.5 on a 10-point scale)

aSubjects' weights and cigarette weights were not given. Calculation based on 85-kg bodyweight and 1-g cigarette weight. Note that some THC would have remained in the cigarettebutt and some would have been lost in sidestream smoke, so these represent maximal possible doses. Actual doses would have been slightly less.

bBased on estimated average 85-kg weight of 11 men 18-35 years old.

cBased on approximate 80-kg weight of subjects (including men and women).



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