Journal List> Manuscripts NIHPA Author
J. Anal. Toxicology, 33 (8) October 2009; 469-477. PMCID: PMC3159863
NIHMSID: NIHMS317047
Implications of plasma Δ 9-tetrahydrocannabinol, 11-hydroxy-THC, and 11-nor-9carboxy-THC. Concentrations in chronic cannabis smokers
Erin L. Karschner, 1 Eugene W. Schwilke, 1 Ross H. Lowe, 1 W. David Darwin, 1
Ronald I. Herning, 2 People Jean Cadet, 2 Marilyn A. Huestis *
1 Research Program of Chemistry and metabolism of drugs, internal, National
Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200,
Baltimore, Maryland 21224
2 Research Program, Molecular Neuropsychiatry, internal, National Institute on Drug
Abuse, National Institutes of Health, 251 Bayview Blvd., Suite 200, Baltimore,
Maryland 21224
* Author to whom correspondence should be addressed: Marilyn A. Huestis, PhD,
Chief Research Program, chemistry and drug metabolism, internal, NIDA, NIH,
Biomedical Research Center, Suite 200, 251 Bayview Blvd, Room 05A-721,
Baltimore, MD . 21224.Email:
Δ 9-tetrahydrocannabinol (THC) is commonly found in toxicology samples taken from
drivers suspected of driving under the influence of a psychoactive substance and
accident investigations. Cannabinoid concentrations were determined in 18 cases of
long-term, intensive cannabis smokers, present during the test on a stationary ward
for seven days monitored abstinence. The concentrations of THC, 11-hydroxy-THC,
and 11-nor-9-carboxy-THC (THCCOOH) were evaluated quantitatively in a twodimensional gas chromatography-mass spectrometry and cryofocusing. THC
concentration was greater than 1 ng / ml, nine (50.0%) participants (1.2-5.5 ng / ml)
on the seventh day of abstinence. THCCOOH detected (2.8-45.6 ng / ml) in all
participants on the seventh day of the study. THC and THCCOOH, respectively, the
median decrease in the concentration in percent (n = 18) were 39.5% and 72.9%
from 1 to 7 Most (88.9%) participants had at least one sample with an increase in
THC compared to the previous day. The duration and concentration of cannabis
THCCOOH levels were positively correlated on days 1-3 (R = 0.584-0.610, p =
0.007-0.011). There was no significant correlation between THC concentrations>
0.25 ng / ml, and body mass index on days 1-7 (R = -0.234-0.092, p = 0.350-0.766).
Measurable concentrations of THC after seven days of abstinence may indicate a
potential mechanism of adrenal dysfunction, and neurocognitive function observed in
chronic marijuana use. The presence of THC in plasma for seven days of controlled
abstinence, suggesting that its detection may indicate recent use in the everyday
behavior of cannabis users.
Δ 9-tetrahydrocannabinol (THC) is the main chemical component responsible for the
euphoric effects and changes in cardiovascular function. The psychomotor
disturbances and Neurocognitive performance, are responsible pharmacodynamically
other acute THC, and especially its psychoactive metabolite 11-hydroxy-THC (11OH-THC). Neuropsychological defects may persist in chronic users of cannabis
during several days of abstinence (1 - 6). Significantly greater deficits were observed
in 77 drug users with marijuana abstinence on days 0, 1 and 7 but not 28 as
compared to former users of cannabis (2, 7). In contrast to other reported reduction in
cortical motor activity (8) and neurocognitive impairment (4) after 28 days or more
documented abstinence in chronic, heavy users of cannabis. In addition, the
duration, not frequency of cannabis use was proposed as a key factor in the
deterioration of performance (5).
THC is highly lipophilic, is largely stored in adipose tissue (9, 10) after chronic
exposure to the slow release over time back into the blood (11, 12). This can lead to
differences in the windows of detection of THC in the blood of occasional and regular
users of cannabis. Rate-limiting step in the terminal elimination half-life of THC after
chronic exposure has been demonstrated in dogs is a slow release of THC from
tissue stores (11). Forensic toxicologists rely on drug detection window, the time
between first and last measurable drug concentration in biological fluid to confirm the
evidence of driving under the influence of drugs. As the concentration of drug in the
brain are not available in the persons living, blood or plasma exposure of most
concern to the drug at its site of action.
Acute administration of smoked 1.75 or 3.55% THC cigarettes and six occasional
users of cannabis yielded mean ± SD plasma levels of THC detection times 7.2 ± 1.6
h (range 3.12 h) and 12.5 ± 3.1 h (range 6.27 h) (13) with a limit of quantification
(LOQ) of 0.5 ng / mL THC. There are limited data interpretation levels after chronic
exposure of THC hemp for two reasons: ethical and safety concerns limit the
administration of chronic doses of smoked and the high cost and difficulty of
continuous monitoring, data collection and analysis of samples during prolonged
excretion of cannabinoids. Early report indicates that the mean plasma
concentrations of only 0.86 ± 0.22 ng / mL THC, 0.46 ± 0.17 ng / ml 11-OH-THC and
45.8 ± 13.1 ng / ml THCCOOH in frequent users of marijuana 12 h after the last use
of cannabis (14). However, more recent studies suggest that THC levels 24-48 h
after the last of cannabis may be 1.2-6.4 ng / ml in 16 frequent cannabis users daily,
who stayed on the ward detoxification (15). During prolonged exposure to marijuana,
THC in plasma half-life was estimated at 4.1 days in two men (12).
Our study examines the THC, 11-OH-THC and disposition THCCOOH in plasma of
18 regular users of cannabis during the seven days continuously monitored
abstinence on a secure research unit. These plasma levels of THC detection times
after prolonged cannabis exposure strongly influence the interpretation of
cannabinoid concentrations and driving under the influence of drugs (DUID) laws. We
hypothesize that residual THC concentrations in the brain after chronic THC
exposure may be the source of the observed neurocognitive impairment in abstinent
frequent users, and now provide pharmacokinetic data to support this hypothesis.
Users of marijuana (21-45 years) with many years of self-reported frequent use
were called to the National Institute on Drug Abuse (NIDA) Institutional Review Board
approved the study. Participants were required to have a positive cannabinoids in
urine immunological tests greater than 100 ng / ml. Exclusion criteria included
clinically significant cardiovascular, pulmonary, endocrine, hematologic, and hepatic
dysfunction. Participants were excluded if it presented the story of past or present
mental disorders (eg post-traumatic stress, anxiety or depression), as defined in the
Diagnostic and Statistical Manual of Mental Disorders IV. In addition, any history of
neurological diseases, including head trauma resulting in loss of consciousness,
seizure disorders, and stroke, were excluded. Women of childbearing potential may
be pregnant or lactating and were required to use medically accepted methods of
birth control or abstain from sexual intercourse throughout the study. Participants
provided voluntary written consent. Medical (physical examination, ECG, blood and
urine biochemistry) and psychological assessment, including self-reported history of
drug use were conducted.
Participants lived in the inner NIDA Research Program (IRP) safe clinical device for
24 h medical surveillance during testing to ensure abstinence from cannabis. Once
adopted, the things all the participants were searched for drugs. Participants were
constantly monitored and no visitors were allowed. Respondents had access to a
universal gym, exercise bike, and a safe area for recreation yard. Financial
compensation for participation have also been provided. Meals were ordered from
the hospital cafeteria, and no diet or fluid restrictions were imposed.
Plasma sampling
Five milliliter of whole blood samples were collected from the venous catheter into
sodium heparin tubes at the time of adoption, and generally at 9 am each day thereafter seven days. Permanent venous catheters have been replaced at least once
every 72 h. Blood was collected, stored on ice, centrifuged and plasma separated
within 2 hours of plasma was transferred to cryotubes and stored at -20 ° C until
analysis.
Analysis of samples
Plasma samples were analyzed for cannabinoids by an approved two-dimensional
gas chromatography mass (2D-GC-MS) spectrometry method for simultaneous
quantification of THC, 11-OH-THC and THCCOOH (16). In brief, the protein in 1 ml of
plasma was precipitated by adding 2 ml of cold acetonitrile, while vortex mixing. After
centrifugation, the supernatant was decanted into 3 ml of sodium acetate buffer (pH
4.0), mixed and applied to the conditioned 200-mg ZSTHC020 ® solid phase
extraction (SPE) columns (United Chemical Technologies, Bristol, PA). The columns
were washed with 3 mL of deionized water, 2 ml of 0.1 N hydrochloric acid /
acetonitrile (70:30, v / v) and dried by full vacuum for 20 minutes. Analytes eluted
with 1 x 3 ml and 1 x 2 ml of hexane / ethyl acetate (80:20, v / v). Eluents were dried
under nitrogen and the derivatives of 25 uL of N, O-bis-(trimethylsilyl)
trifluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TMCS) at 70 ° C for 30 min.
Trimethylsilyl derivatives of the extracts were injected (3 mL) for Agilent 6890/5973
2D-GC-MS (Santa Clara, CA) with a scream-ofocusing operate in electron (EI) /
selected ion monitoring (SIM) mode. 2D-GC-MS effectively separated the analytes
from the matrix at cryofocusing significant increase in the signal. THC ions m / z 386
(quantification ion) and the elimination of three ions, 371, 303 and 387th The method
was fully validated for all ions, the occasional interference of endogenous ion
requires the use of 387 as a qualifier to identify the ION 2 in place of the 303rd If
necessary, all the patterns and quality control samples were evaluated similarly.
Calibration curves Split (low, 0.25-25, and high, 25-100 ng / ml) had r 2 ≥ 0.990. LOQ
was 0.25 ng / ml for THC and THCCOOH and 0.50 ng / ml 11-OH-THC. Within one
inaccuracy (n = 5, tests = 4) were 1.5-13.6% for all analytes and interassay
imprecision (n = 20) was less than 10.7%.
Analysis of data
Statistical analysis was performed with SPSS for Windows, version 13.0 (Chicago,
IL) and Microsoft Excel 2002 for Windows. Body mass index (BMI) is a statistical
approximation of the total amount of body fat calculated using an individual's height
and weight. BMI is calculated BMI = 703 x [weight (kg) / height 2 (in 2)]. When the
statistical assessment of the amount of cannabis used concentration of
cannabinoids, one blunt was considered equivalent to four joints, such as Bolla et al.
(4). The correlation coefficient (R) and p value (p) are the statistical calculations,
which in combination, can help to determine whether there is a significant relationship
between variables. If the p value <0.05, the compound is considered to be
statistically significant.
Eighteen frequent cannabis smokers (6 males, 12 females) completed the study.
Participant demographic data and self-reported cannabis as listed in Table I. The
World Health Organisation defines a person with a BMI <18.5 as underweight, 18.624.9 normal, 25-29.9 as overweight, and ≥ 30 for obesity (17). Participant BMI ranged
from 21.2 to 42.5. The average age of first use of cannabis was 14.5 years (range,
21.9 years) with 22.2 years of experience smoking marijuana. Most reported using
cannabis daily during the two weeks before the start of the study more than half of
smoking on the day of adoption. Only one participant reported smoking marijuana
less than 7 of the last 14 days. The amounts of smoked cannabis were variously
described as a joint (marijuana cigarette), blunts (cannabis plant material rolled into a
cigar), ounces, or penny (ie the amount of cannabis available for $ 10). All
participants drank alcohol during the month before admission, and all except two
(participants L and P) smoking. There are no reports of other illicit drugs during the
two weeks prior to admission.
Table I
przyjęciem do szpitala.
Participant Demographics and self-reported history of smoking marijuana
A total of 126 plasma samples were analyzed for THC, 11-OH-THC and THCCOOH
by 2D-GC-MS. It was necessary to use the 387 ion to get good results for the 4 (or
3.2%) samples, because the interference from endogenous ion 303rd All samples for
quality control and indicators of authentic specimens of "ion were allowed on the
basis of criteria established by the calibrators assayed in batches for quantifier
elimination and ion indicators.
The median concentration of cannabinoids from the adoption of the seven days of
abstinence are presented in Table II. Median (n = 18) THC concentration on
admission (day 1) was 1.9 ng / ml concentration range from 0.5 to 9.0 ng / ml (Table
II and Figure 1). THC is still detectable in 16 marijuana smokers on day 7 in median
concentrations of 1.1 ng / ml. Participant L had the highest THC in six of the seven
days the concentration of more than 1.5 times the interquartile range (IQR) on days
1, 2, 3 and 6, and more than 3 times the IQR on days 4 and 7 (Fig. 1 and and2). 2).
11-OH-THC was detected only in 17 (13.5%) samples. The median 11-OH-THC
concentrations in 18 people at the party was not detected (ND) with concentrations
ranging from ND and 7.0 ng / ml. Only one participant was positive for the
hydroxylated metabolite on 5, there were no further 11-OH-THC specimens
exceeding 0.5 ng / ml LOQ after that time. THCCOOH was the quantification of all
the participants for seven days of abstinence. THCCOOH concentrations ranged
from 12.1 to 205.4 ng / ml on day 1 and dropped to 2.8-45.6 ng / ml on the last day of
the study. All but three participants had THCCOOH concentrations greater than 5.0
ng / ml on day 7
Table II
Median (n = 18) and a range of concentrations in plasma Cannabinoid within seven
days of continuous abstinence monitored, the number of participants in
concentrations above the common analytical Cutoffs (1, 2 and 5 ng / ml) and the
LOQ of 0.25 ng / ml for THC and THCCOOH ( more ...)
Figure 1
Plots field Δ 9-tetrahydrocannabinol (THC) elimination from plasma during continuous
monitoring of abstinence in 18 regular users of cannabis. Thin horizontal lines define
the range of concentrations, fields 25 and 75 percentiles (interquartile range, IQR),
(more ...)
Figure 2
Δ 9-tetrahydrocannabinol (THC, ♦), 11-hydroxy-THC (11-OH-THC, ■) and 11-nor-9carboxy-THC (THCCOOH, ○) concentration of the participant (A) who had smoked
cannabis to 22 years (the longest use), participant K (B) who had smoked cannabis
(more ...)
Cannabinoid concentrations generally decreased over time (Table III) with a median
decrease from day 1 to day 2 of 24.6% to 23.6% for THC and THCCOOH. The mean
percent decrease in concentrations of from 1 day to 7 was 39.5% for THC (n = 11)
and 72.9% for THCCOOH (n = 18). Average percentage of THC decreases from 1
day to 7 ranged between 2.7 and 75.4%. Reducing the concentration of the analyte
was variable from day to day in the participants of THC [coefficient of variation (CV)
33.9-125.6%] and THCCOOH (CV 27.9-100.2%). THC concentrations sometimes
increased by the subsequent days, 88.9% of participants had increased at least one
day, and at least four participants had a THC increases daily. THC increases the
median percent were from 3.7 to 27.5%. Few THCCOOH increases were observed
an average increase of 4.5 to 60.9%. Median changes in the concentrations of THC
and THCCOOH were higher in those who smoked on the day of admission (n = 10)
than in those who have recently smoked the previous day (n = 8), although there
were no significant differences in mean changes. Median changes in the
concentration of THC in smokers on the adoption was -0.6 ng / ml, an increase of 1.3
ng / ml (n = 2) and a decrease of 0.2-3.7 ng / ml (n = 8), and for THCCOOH - 7.4 ng /
mL increase of 2.5-25.1 ng / ml (n = 2) and decreases of 1.4-47.2 ng / ml (n = 8).
Median changes in the concentration of THC in smokers days prior to admission was
0.1 ng / ml increased from 0.1 to 0.4 ng / ml (n = 5) and a decrease of 0.0-0.2 ng / ml
(n = 3 ), for THCCOOH -6.0 ng / mL increase of 4.7 ng / ml (n = 1) and decreases of
0.0-16.7 ng / ml (n = 7).
Table III
The median, minimum and maximum percentage increase and decrease in THC (n =
11) and THCCOOH (n = 18) daily concentrations within seven days of continuous
abstinence monitored
Variable concentrations of cannabinoids were observed between participants.
Participant, normal weight 36-year-old man, had the longest time (22 years) of
smoking cannabis. In the first day, the concentration of THC in plasma Participant 4.9
ng / ml and decreased to 1.2 ng / ml on day 7 (Figure 2A). 11-OH-THC only
measurable on admission to this topic. THCCOOH had the highest concentrations on
admission (205.4 ng / ml) for 3 days (111.1 ng / ml), followed by a slow decrease to
32.0 ng / ml on day 7. Participant K, overweight 26-year-old woman, had the shortest
life within 2 years. For the first time smoking marijuana for 21 years and reported
average consumption of 7 cannabis cigarettes a day. Participant K in plasma THC
and 11-OH-THC concentrations of 5.3 and 4.0 ng / ml, respectively, for acceptance
and decreased to 1.6 ng / ml. None were detected on day 2 (Fig. 2B). She remained
positive for THC each of the seven days. Plasma concentrations THCCOOH
Participant K ranged from 59.6 ng / ml on day 1 to 9.0 ng / ml on day 7. Participant L,
with normal-weight 21-year-old woman, was a participant with the highest
concentrations of THC in six of the seven days (Fig. 1 and and2C). 2C). THC
concentrations decreased from 9.0 ng / ml on day 1 to 3.8 ng / ml on day 5 and were
higher (5.5 ng / ml) on day 7. 11-OH-THC was detected for the first four days, the
longest duration of detection of cannabinoids. Participant L's THCCOOH
concentrations were between the third and fifth highest in seven days. THC
decreases from 1 to 7 were 75.4, 83.1 and 38.9% for participants A, K and L,
respectively, 84.4, 84.9 and 65.8%, respectively, for THCCOOH. Mean ± SD plasma
cannabinoid found in Figure 2D.
There were no statistically significant differences in concentrations of THC or
THCCOOH each day study found between normal (n = 7), overweight (n = 6) or
obese (n = 5) patients based on BMI. In addition, there was no correlation between
THC concentrations greater than the LOQ in 1-7 days and BMI (R = -0.234-0.092, p
= 0.350-0.766). Furthermore, no significant correlation of percent decrease in THC (R
=- 0.315, p = 0.203), or THCCOOH (R = -0.308, P = 0.213) in plasma from 1 to 7,
and BMI.
The relationship between years of cannabis and cannabinoids levels by seven days
of abstinence was examined. There were no statistically significant differences in
concentrations of THC on 7 based on the use of cannabis ≥ 10 years (group 1) or
<10 years (group 2) (p = 0.961). There was no correlation between years of use and
concentration of THC on days 1-7 (R = -0.211-0.063, p = 0.401-0.968). There also
was no relationship between the concentration of THC or THCCOOH on days 1 and
7 and the frequency of cannabis use (R = -0.375-0.042, p = 0.125-0.986) or the
amount smoked per day (R = 0.044-0.260, p = 0.350- 0876). In addition, there was
no relationship between the duration of use and the percentage decrease in THC (R
= -0.208, P = 0.407) or THCCOOH (R = 0.051, p = 0.840) from 1 to 7 days. However,
plasma concentrations on days of abstinence THCCOOH 1.3 were significantly
correlated with duration of use of cannabis (R = 0.584-0.610, p = 0.007-0.011).
THCCOOH / THC ratios were assessed within seven days of abstinence. Median
THCCOOH / THC ratios were 16.0 on day 1 (n = 11, range 11.2-42.1), generally
decreases between days 1 and 3 and stabilization for 4-7 days. By day 7, the median
THCCOOH / THC was 7.7 (n = 11, range 4.4-26.7). Median THCCOOH / THC ratios
for the 11 participants with measurable THC and THCOOH for each of the seven
days are shown in Figure 3.
Figure 3
11-nor-9-carboxy-Δ 9-tetrahydrocannabinol (THCCOOH, ○) for Δ 9tetrahydrocannabinol (THC, ♦), the median ratios in 11 participants with THC and
THCCOOH concentrations greater than 0.25 the limit of quantification ng / ml for
each ( more ...)
This study presents the first time in the plasma cannabinoid time within seven days of
monitored abstinence in chronic cannabis smokers. THC concentrations above 1 ng /
ml for seven days in the nine frequent users of cannabis, and THCCOOH was
measurable in all participants each day. Marijuana is the most widely used drugs
worldwide and the higher potency of cannabis in recent years (18) led to increased
dependence on cannabis (19) and a much greater need for drug treatment (20).
Severe chronic cannabis use may lead to impaired cognitive abilities. There are two
main hypotheses for the loss observed after long-term heavy cannabis use. In one of
them is a partial improvement in productivity as a result of prolonged exposure.
Solowij et al. (21) found that cannabis smoking an average of 9.0 ± 3.8 years only
partially recovered brain function after prolonged abstinence. The second hypothesis
suggests that cognitive deficits in heavy users can often return to normal functioning
after a long abstinence (22). Current heavy smokers of cannabis with more than
5,000 life uses impaired performance on memory tasks at baseline and after 1 and 7
days of abstinence, but no significant differences at 28 days compared to control
subjects with less than 50 events of life to use cannabis (7 , 22). In this study, we
found significant relationship between baseline serum creatinine normalized urine
THCCOOH and verbal learning and memory performance on abstinence hemp 1
Other researchers have documented reduced neurocognitive performance in chronic
marijuana users at 28 days of abstinence (4). Yes, research is needed to determine
whether the loss in performance found after prolonged cannabis exposure can be
reversed with extended abstinence and if the reversal of impairment and correlate
with the concentration of THC.
We hypothesize that reducing the concentration of THC in the brain during
abstinence correlates with improvement in neuropsychological performance. In our
study, THC was detected in plasma on abstinence 7 in 88.9% of respondents. There
are two evidence to date suggests that THC may be present in the brain longer than
in blood. Brunet et al. (23) showed that the concentration of THC in the blood
declined faster than the brain, THC, when modeled in a large white pig. In addition,
THC has been detected in the human brain than in blood in 12 postmortem cases
positive for the inactive metabolite THCCOOH (24).
Unfortunately, in the present study, the blood may be collected for seven days was
insufficient for complete elimination of THC in nine of 18 heavy drug users
participating in the study of patients in the study. At that time it was difficult to justify
the seven days of blood collection for ethical review committee because of the belief
that the THC will be quickly eliminated, as is the case in a few hours of acute
exposure to occasional users of marijuana. Previous studies conducted in our
laboratory have shown that THC concentrations decreased rapidly and fell below the
quantitative limits of about 12.5 ± 3.1 h after the 3.55% THC cigarette (13). Moreover,
the average THC concentration only 0.86 ± 0.22 ng / ml in chronic users 12 hours
after last cannabis survey Peat et al. (14). 13-day period of detection of THC was
described by three chronic cannabis smokers were administered 60 mg of THC over
2-day period (12). However, analytical methods are not reported qualifier ions, LOQ,
or other method validation parameters for several samples analyzed by GC-MS.
Recently, the participants lived in a closed research unit for as long as 30 days of
abstinence from the collection of all urine samples. Specifically hydrolyzed urine
samples of E. coli β-glucuronidase for the analysis of free THC and 11-OH-THC (25).
We have measurable THC (≥ 2.5 ng / ml) in urine for up to 24 days after the start of
abstinence on a closed research unit for monitoring of 24 h (26). The results of urine
in conjunction with our plasma data suggest that residues of THC THC in the brain
may be responsible for neurocognitive impairment seen after heavy and frequent use
of cannabis.
THC has high partition coefficient octanol / water (log P = 6.97) (27) and rapidly
distributed to lipophilic tissues. Severe, frequent user of cannabis with a larger
amount of fat is expected to have a greater body weight of THC compared to those
with less body fat. However, in this study, the concentration of cannabinoids in 18
chronic drug users were not correlated with BMI values in any one day of testing.
Furthermore, no significant differences in THC or THCCOOH concentrations between
normal participants with overweight and obese. Furthermore, no significant
correlation between THC percent reduction from 1 to 7, and BMI. BMI as a statistical
function of height and weight may not be the strongest measure of body fat, future
studies should consider measuring body fat percentage.
Solowij et al. suggested that the duration of cannabis use was associated with
cognitive impairment (5). In this study, no significant correlation was found between
THC concentrations and BMI or a history of cannabis use. However THCCOOH
concentrations were positively associated with duration of use for 1-3 days. This may
indicate that the longer a separate cannabis, the higher the concentration THCCOOH
the first three days of abstinence. The best estimate for THCCOOH half-life is
approximately 3-4 days (12, 28). THCCOOH average decrease in concentration
between days 1 and 5 was 58.7%, which means that the elimination phase has not
been achieved.
Metabolite / parent drug ratios were calculated to further evaluate the excretion of
cannabinoids in this unique group. THCCOOH / THC median ratios generally
decreased from days 1-4 with a plateau from 4-7 days. The median concentrations of
THC and THCCOOH fell 39.5% and 72.9% from 1 day to 7 These data suggest that
the residual and emerging THCCOOH of THC metabolism may be eliminated from 1
to 4 This is followed by THCCOOH formation, which is the speed of the THC release
from tissues and subsequent metabolism, as indicated by stable THCCOOH / THC
ratios from 4 to 7 days. One would expect that in this case, 11-OH-THC
concentrations would be equal to THCCOOH, but a shorter half-life of this metabolite
(29), higher analytical LOQ of 0.5 ng / ml, and significantly lower concentrations of
residues 11 - OH-THC after frequent smoking can cause a decrease in concentration
of 11-OH-THC. Only 44.4% of participants had measurable 11-OH-THC
concentrations in the adoption, that number dropped to 16.7% on day 2 When
smoked administration, low 11-OH-THC concentrations of THC are formed by liver
microsomal oxidation (approximately 5-10% THC) (13, 29). In contrast to oral first
pass metabolism of THC produces equivalent or sometimes higher 11-OH-THC
concentrations (13, 29).
Plasma cannabinoid excretion was variable between individuals as demonstrated in
the profiles of three people "in the urine in Figure 2. The participant with the longest
history of cannabis exposure (A), one could determine the concentration of THC in
the course of the study, and on day 3, the concentration of THC and decreased
THCCOOH parallel fashion. contestant who recently became a user of marijuana (K)
had a large drop in THC and THCCOOH on the first day and continuing low levels of
THC in the next six days. In addition, the participant smoked cannabis K past the
date of adoption, which may explain the large drop the THC and THCCOOH
concentrations observed between days 1 and 2 11-OH-THC concentrations were
greater than the LOQ for four days in L's plasma Participant, the Participant with the
highest concentrations of THC in six out of seven days.
Most participants (88.9%) had at least one day in which the concentration of THC
increase from the previous day. Possible reasons for increase in the release may
include differences in exercise, diet, or water. Although THC and THCCOOH median
percent decreases were similar in most days, the most dramatic differences occurred
between day 2 and 3 Nearly five times higher can be explained by reduced excretion
THCCOOH high concentrations of residues THCCOOH between day 2 and 3, similar
decreases in THC and THCCOOH from 4-7 days. This may be due to the THC
release and metabolism of tissues quickly. Importantly, there were increases and
decreases are based on median data, thus reducing the variability between
participants.
Limitations of the study included to rely on their own assessment, data analysis as
regressors, the limited amount of sample and long-term storage of clinical samples.
Participant L, who had the highest concentration of THC in plasma, are reported
using only three of the last 14 days, which suggests inaccuracies in reporting. A very
sensitive method for 2D-GC-MS was developed for the analysis of residues of
cannabinoids in urine (16). LOQs 0.25 ng / ml for THC and THCCOOH and 0.5 ng /
ml 11-OH-THC have been achieved. Sometimes there was difficulty in obtaining
adequate blood volume or more studies were needed, which reduces the available
volume of blood than usual 1-ml sample size. In these cases, the sample volume was
reduced, resulting in a higher LOQ for this sample. A third limitation involved storing
samples in polypropylene cryotubes to five years at -20 ° C. The concentration of
cannabinoids decreases were observed when the specimens were frozen for a long
time before the test (30), although it may just cause under-, not over-, assessment of
the concentration of cannabinoids .
Forensic interpretation
There are several important consequences of this research for forensic toxicology.
THC concentrations were greater than 1 (n = 9) and 2 (n = 4) ng / ml for seven days
in cannabis smokers often when constantly monitored abstinence. These
concentrations are commonly used to mark the last days of smoking marijuana and,
in some countries may mean sacrificing performance. In some U.S. states, per se
DUID laws may specify the impairment on the basis of the presence of measurable or
low THCCOOH or plasma. THCCOOH inactive metabolite of THC is that it has no
impact on performance. Some countries have legal "measurable controlled
substance or metabolite of a controlled substance in the human body" (31) is illegal
while driving. In this study, THCCOOH was detected in plasma of all participants in
the study of the day 7 concentrations greater than 5.0 ng / ml in 83.3% of heavy,
chronic cannabis smokers.
Although neuropsychological impairment (32 - 36) and increased risk of motor vehicle
accidents (37) occurs when under the influence of acute THC, it was difficult to relate
these results to specific blood or plasma. Risk of accidents attributed to cannabis
were assessed in 3398 Australian driving fatalities. Drivers with detectable levels of
THC in blood was 2.7 times (95% CI 1.0-7.0) more likely to be culpable in the
accident in relation to drug drivers (37). The probability of guilt increased 6.6-fold
(95% CI 1.5-28.0) when the driver had a blood THC concentrations at or above 5.0
ng / ml (approximately 10 ng / ml plasma).
Recently experimental studies suggest that cognitive impairment in the THC serum
concentrations of 2-5 ng / ml, the critical task of tracking performance skills important
(38). Within these limits, four of our participants will be judged worse after seven days
of abstinence hemp. Other researchers conducted a comprehensive meta-analysis of
experimental data and proposed a 10.7 ng / ml of serum THC as a per se within the
kidney (39). Based on this evaluation, L participant may be considered disorders in
our study day 4, three days after the last use of marijuana. On the other hand, the
concentration of THC in blood at the time the case is likely much higher than in the
time of blood are collected by hospital staff and police, which is generally 2-4 hours
after the incident. Thus, although the per se limits can be useful if the impairment can
not be documented through field sobriety tests (40, 41), study drug recognition
expert, or other measures of performance, the limits as high as 2.5 ng / ml prevents
the conviction of many drivers who are under the influence of drugs documented poor
performance of much lower concentrations of THC at the time of blood collection.
Jones et al. (42) clearly shows that 77-90% of Swedish operators of motor vehicles
from 1995 to 2004 who had recently smoked marijuana avoid prosecution, if 5 ng / ml
of whole blood restrictions were applied.
Future research
Future studies of cannabinoid excretion in chronic users of cannabis should be
carried out more than seven days and include psychomotor and cognitive
performance measures to document the presence or absence of impairment. If the
concentration of THC was accompanied by measurable neuropsychological
impairment, is the rationale for implementing the law se. Longer term monitoring will
allow for more comprehensive data on recently cannabinoid detection in plasma often
daily users of cannabis and associated communication disorders. Repeated blood
sampling is also recommended so that the final determination in the life of this unique
population using cannabis. In addition, the sample should be analyzed after a short
period of storage, which facilitates the development of models to predict the time of
last use of cannabis. Although the estimation models were developed last cannabis
for occasional users of cannabis and verified data from multiple studies smoked and
oral administration (43 - 45), the models have not been confirmed in a heavy, longterm smokers of marijuana a day.
Conclusion
This is the first study to determine plasma concentrations of cannabinoids in chronic
cannabis smokers within seven days of monitored abstinence. THC concentrations
above 2 ng / ml were found in many animals on the seventh day marijuana
abstinence, suggesting the presence of THC in the plasma does not necessarily
mean past smoking cannabis in chronic cannabis users. These data may influence
the clinical pharmacotherapy of cannabinoids, cannabis dependence treatment and
per se DUID legislation in the U.S. and abroad. It also suggests a mechanism for
adrenal dysfunction observed in neurocognitive chronic cannabis smokers after
several days of abstinence.
Acknowledgements
The authors would like to thank Allan J. Barnes, support data analysis and Kathleen
Demuth, Janeen and John Etter Nichels using clinical studies. These studies were
supported by the Internal Research Program National Institute on Drug Abuse,
National Institutes of Health.
First Pope HG, Yurgelun-Todd D. Other cognitive effects of heavy marijuana use
among students. J. Am. Med. Assoc. 1996, 275 :521-527.
Second Pope H, Gruber, Hudson J, Huestis M, Yurgelun-Todd D.
Neuropsychological performance in long-term users of marijuana. Arch. Gen.
Psychiatry. 2001; 58. :909-915 [PubMed]
Third Block RI, Ghoneim MM. Effects of chronic marijuana use on human cognition.
Psychopharmacology (Berl) 1993; 110. :219-228 [PubMed]
4th Bolla KI, Brown K, Eldreth D, Tate K, Cadet JL. . Dose-related neurocognitive
effects of marijuana. Neurology 2002; 59. :1337-1343 [PubMed]
5th Solowij N, Stephens RS, Roffman RA, Babor T, Kadden R, Miller M, Christiansen
K, McRee B, Vendetti J cognitive functioning long-term heavy cannabis users
seeking treatment. J. Am. Med. Assoc. 2002, 287 :1123-1131.
6th Fletcher JM, Page JB, Francis DJ, Copeland K, Naoussa MJ, Davis CM, Morris
R, Krauskopf D, Satz P. Cognitive correlates of long-term use of marijuana in Costa
Rican men. Arch. Gen. Psychiatry. 1996, 53. :1051-1057 [PubMed]
7th Pope HG, Gruber AJ, Hudson JI, Huestis MA, Yurgelun-Todd D. Cognitive
measures of long-term users of marijuana. J. Clin. Pharmacol. 2002; 42:. 41S-47S
[PubMed]
8th Pillay SS, Rogowska J, Kanayama G, Gruber S, N Simpson, Pope HG, Yurgelun-
Todd DA. Cannabis and motor function: fMRI changes following 28 days of
discontinuing treatment. Exp. Clin. Psychopharmacol. 2008; 16. :22-32 [PubMed]
. 9. Kreuz DS, Axelrod J. Delta-9-tetrahydrocannabinol: Location in adipose tissue.
Science 1973, 179. :391-393 [PubMed]
10th Agurell S, Nilsson IM, Ohlsson, Sandberg F. The metabolism of tritium-labeled
1-tetrahydrocannabinol in rabbits. Biochem. Pharmacol. 1970; 19. :1333-1339
[PubMed]
11th Garrett ER, Hunt CA. Pharmacokinetics of delta-9-tetrahydrocannabinol in dogs.
J. Pharm. . Sci 1977, 66. :395-406 [PubMed]
12th Johansson E, Agurell S, Hollister LE, Halldin MM. Prolonged half-life of delta-1tetrahydrocannabinol in plasma of chronic marijuana. J. Pharm. Pharmacol. 1988; 40.
:374-375 [PubMed]
13th Huestis MA, Henningfield JE, Cone EJ. Cannabinoids in the blood. I. Absorption
of THC and the creation of 11-OH-THC and THCCOOH during and after smoking
marijuana. J. Anal. Toxicology. 1992; 16. :276-282 [PubMed]
14th Peat MA. Distribution of delta-9-tetrahydrocannabinol and its metabolites. In:
Baselt RC, editor. Advances in Analytical Toxicology II. Chicago, IL: Year Book
Medical Publishers, 1989. pp. 186-217.
15th Skopp G, L. Potsch concentration of cannabinoids in the spot serum samples
24-48 hours after cessation of smoking marijuana. J. Anal. Toxicology. 2008, 32.
:160-164 [PubMed]
16th Lowe RH, Karschner EL, Schwilke EW, Barnes AJ, Huestis MA. Simultaneous
quantification of Δ 9-tetrahydrocannabinol (THC), 11-hydroxy-Δ 9tetrahydrocannabinol (11-OH-THC), and 11-nor-Δ 9-tetrahydrocannabinol-9carboxylic acid (THCCOOH) in plasma by means of two gas chromatography,
cryofocusing and electron mass spectrometry. J. Chromatogr. A. 2007; 1163. :318327 [PMC free article] [PubMed]
. 17. World Health Organization. Physical Status: The Use and Interpretation of
Anthropometry Geneva, Switzerland: World Health Organization, 1995. p. 47
18th ElSohly MA, Ross SA, Mehmedic Z, Arafat R, Banahan BFI. Trends power of Δ
9-THC and other cannabinoids in confiscated marijuana from 1980-1997. J. Forensic
Sci. 2000; 45. :24-30 [PubMed]
19th Stinson FS, Ruan WJ, Pickering R, Grant BF. Disorders related to the use of
hemp in the United States: prevalence correlates and comorbidity. Psychol. Med.
2006; 36. :1447-1460 [PubMed]
20th Carpenter KM, McDowell D, Brooks DJ, Cheng WY, Levin FR. Preliminary
examination. Double-blind comparison of nefazodone, bupropion SR and placebo in
the treatment of cannabis dependence Am. J. Addict. 2009; 18. :53-64 [PMC free
article] [PubMed]
. 21 Solowij N. Do cognitive recover after cessation of cannabis use? Life Sci. 1995,
56 :2119-2126. [PubMed]
22nd Pope HG, Gruber AJ, Hudson JI, Huestis MA, Yurgelun-Todd D.
Neuropsychological performance in long-term users of marijuana. Arch. Gen.
Psychiatry. 2001; 58. :909-915 [PubMed]
. 23 Brunet B, C Doucet, Venisse N, Hauet T, Hebrard W, Y Papet, Mauco G, Mura,
P. Validation of Large White Pig as an animal model to study the metabolism of
cannabinoids: an application to the study of THC distribution of human tissues.
Forensic Sci. Int 2006, 161 :169-174. [PubMed]
24th Mura P, Kintz P, Dumestre V, Raul S, T. Hauet THC can be detected in the
brain in the absence of blood. J. Anal. Toxicology. 2005; 29. :842-843 [PubMed]
25th Abraham TT, Lowe RH, Pirnay SO, Darwin WD, Huestis MA. Simultaneous GCEI-MS determination of Δ 9-tetrahydrocannabinol, 11-hydroxy-Δ 9tetrahydrocannabinol and 11-nor-9-carboxy-Δ 9-tetrahydrocannabinol in human urine
after enzymatic hydrolysis of tandem-base. J. Anal. Toxicology. 2007; 31. :477-485
[PMC free article] [PubMed]
26th Lowe RH, TT Abraham, Darwin WD, Herning R, Cadet JL, Huestis MA.
Enhanced urinary Δ 9-tetrahydrocannabinol in chronic drug excretion excludes the
application as new biomarkers of exposure. Drug Alcohol Depend. July 2009 22, E
pub ahead of print.
27th Thomas BF, Compton DR, Martin BR. Characteristics of lipophilicity of natural
and synthetic analogs of delta 9-tetrahydrocannabinol and its relationship to
pharmacological potency. J. Pharmacol. Exp. . There 1990; 255. :624-630 [PubMed]
28th Johansson E, Halldin MM. Acid excretion half-life of delta1tetrahydrocannabinol-7-oic in heavy marijuana users after smoking. J. Anal.
Toxicology. 1989; 13. :218-223 [PubMed]
29th Wall ME, Sadler BM, Brine D, Taylor H, Perez-Reyes M. Metabolism,
disposition, and kinetics of delta-9-tetrahydrocannabinol in men and women. Clin.
Pharmacol. . There 1983; 34. :352-363 [PubMed]
30th Schwilke EW, Karschner EL, Lowe RH Gordon AM, Cadet JL, Herning R,
Huestis MA. Intra-and interindividual blood / plasma ratio determined by the
cannabinoid 2-dimenJournal analytical Toxicology, Vol. 33, October 2009 interim, the
electron-gas chromatography, mass spectrometry cryofocusing. Clin. Chem. 2009;
55 (6). :1188-1195 [PMC free article] [PubMed]
31st U.S. prosecutors NTLC Institute. American Prosecutors Research Institute,
2006. Appendix 2 Driving under the influence of drugs, a summary of the law of the
State, pp. 1-28.
. 32 Chait LD, Pierri J. Effects of smoked marijuana on human action: a critical
review. Marijuana / cannabinoids. In: Murphy L, Bartke, editors. Neurobiology and
Neurophysiology. Boca Raton, FL: CRC Press, 1992. pp. 387-423.
33rd Kurzthaler I, Hummer M, Miller C, Sperner-Unterweger B, Gunther V, Wechdorn
H, Battista HJ, Fleischhacker WW. Ability effects of cannabis on cognitive functions
and driving. J. Clin. A psychiatrist. 1999; 60. :395-399 [PubMed]
34th Riedel G, Davies SN. Cannabinoid functions in learning, memory and plasticity.
In RG Pertwee, editor. Handbook of Experimental Pharma-logy. New York, NY:
Springer, 2005. pp. 446-470.
35th Hall W, Solowiji N, Lemon J. health and psychological effects of cannabis use.
National Task Force on marijuana. 1994
. 36 Curran HV, Brignell C, Fletcher S, Middleton P, Henry J. Cognitive and
subjective dose-response effects of acute oral delta-9-tetrahydrocannabinol (THC) in
cannabis users rarely. Psychopharmacology (Berl) 2002; 164: 61 - 70 [PubMed]
37th Drummer OH, Gerostamoulos J, Batziris H, Chu M, Caplehorn J, Robertson
MD, Swann P. The share of drug drivers of motor vehicles killed in Australian road
accidents. Accid. Anal. Prev. 2004; 36. :239-248 [PubMed]
. 38 RAMAEKERS JG, Moeller MR, van Ruitenbeek P, Theunissen EL, Schneider E,
Kauert G. Cognition and motor control as a function of Δ 9-THC concentration in
serum and oral fluid: limits of impairment. Drug Alcohol Depend. 2006, 85 :114-122.
[PubMed]
. 39. Grotenhermen F, Leson G, Berghaus G, Drummer OH, Kruger HP, Longo M,
Moskowitz H, Perrine B, RAMAEKERS JG, Smiley, Tunbridge R. Developing limits
for driving under cannabis. Addiction 2007; 102: 1910-1917 year. [PubMed]
. 40. Papafotiou K, Carter JD, Stough C. The evaluation of sensitivity of standard
sobriety tests Field (SFSTs) to detect impairment due to marijuana intoxication
Psychopharmacology (Berl) 2005; 180. :107-114 [PubMed]
41st Papafotiou K, Carter JD, Stough C. The relationship between performance on
the field sobriety test standard, performance and the level of delta-9tetrahydrocannabinol (THC) in blood. Forensic Sci. Int 2005; 155. :172-178 [PubMed]
42nd Jones AW, Holmgren, FC Kugelberg. . Driving under the influence of cannabis:
a 10-year study of age and gender differences in the concentrations of
tetrahydrocannabinol in blood. Addiction 2008; 103. :452-461 [PubMed]
43rd Huestis MA, Henningfield JE, Cone EJ. Cannabinoids in the blood. II. Models to
predict the exposure time of the concentration of marijuana delta-9tetrahydrocannabinol (THC) and 11-nor-9-carboxy-delta-9-tetrahydrocannabinol
(THCCOOH) J. Anal. Toxicology. 1992; 16. :283-290 [PubMed]
44th Huestis MA, ElSohly M, Nebro In, Barnes, Gustafson RA, Smith ML. Estimating
time of last oral marijuana with THC levels of plasma and THCCOOH. No. Prompt
drugs. 2006, 28 :540-544. [PubMed]
45th Huestis MA, Barnes, Smith ML. Estimating time of last use of cannabis from
plasma Δ 9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ 9-tetrahydrocannabinol
concentrations. Clin. Chem. 2005; 51. :2289-2295 [PubMed]