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Now for the meat.....
Cannabinoid Pharmacokinetics and Disposition in Alternative Matrices
16.2.3 Metabolism
THC metabolizes primarily to
- 11-OH-THC,
- THCCOOH and
- glucuronide conjugates.
THC hydroxylation at C9 by hepatic cytochrome
- P450 2C9,
- 2C19, and
- 3A4 enzymes
produces the equipotent metabolite, 11-OH-THC,
- originally thought to be the true psychoactive analyte.
More than 100 di- and tri- hydroxy, ketone, aldehyde, and carboxylic acid THC metabolites have been identified.
Significant 8β-OH-THC and lower 8α-OH-THC concentrations also have been detected.
Some important facts (Huestis 2005) regarding THC metabolism are:
◆ Plasma concentrations of 11-OH-THC following smoking are about 10% those of THC.
◆ Plasma concentrations of 11-OH-THC after oral ingestion are approximately equal to those of THC.
◆ THCCOOH-glucuronide is the principal Phase II metabolite.(p.302)
◆ Plasma THCCOOH concentrations are greater than those of THC 30–45 min after smoking and 1 h after oral ingestion (dronabinol) for occasional cannabis users.
◆ There is no significant difference in metabolism between men and women.
◆ There is large intra- and intersubject variability in the concentration profile of plasma THC and metabolites.
◆ THC is primarily metabolized in the liver but additional drug is metabolized in other tissues including brain, intestine and lung.
◆ After occasional cannabis users smoked 16 and 30 mg THC cigarettes, mean (range) plasma THCCOOH Cmax were
- 24.5 micrograms/L (15–54) and
- 54.0 micrograms/L (22– 101), respectively (Huestis et al. 1992).
The previously cited study by Schwope et al. (2011a, 2011b) described blood and plasma concentration time profiles for THC, 11-OH-THC, THCCOOH, CBD, CBN, THC-glucuronide and THCCOOH-glucuronide following smoking of a 6.8% THC cigarette (Fig. 16.2).
This study demonstrated that within hours THCCOOH-glucuronide, a more water soluble metabolite that is more readily excreted, is the major metabolite in blood and plasma.
THCCOOH-glucuronide can
be detected in blood for many hours,
- but can dissociate into free THCCOOH,
- especially when stored in blood outside the body at room temperature (Skopp and Potsch 2004).
16.2.4 Elimination
Within 5 days, 80–90% of a THC dose is excreted,
- primarily as
hydroxylated and carboxylated metabolites (Huestis 2005).
* More than 65% is excreted in feces, with
* approximately 25% in urine.
Of the many acidic urinary metabolites, THCCOOH glucuronide is primary,
while 11-OH-THC predominates in feces.
Some important facts (Huestis 2005) about THC elimination from the human body include the following:
◆ Elimination half-life for THC is nonlinear with a terminal half-life of about 4.1 days.
◆ Plasma THCCOOH and THCCOOH-glucuronide terminal elimination half-lives in frequent cannabis smokers were, respectively, 5.2 and 6.8 days and 6.2 and 3.7 days in occasional smokers.
◆ Urinary THCCOOH concentrations drop rapidly until approximately 20–50 micrograms/L, then are eliminated with a terminal half-life of about 3–4 days.
◆ The percent of a smoked THC dose excreted in urine over 7 days is about 0.54%.
◆ Detection times in urine after smoking a 3.55% THC cigarette with a 15 micrograms/L urine THCCOOH cutoff concentration is 2–5 days for occasional cannabis smokers
***but can extend to weeks in chronic daily cannabis smokers.
There is much less THC elimination data for chronic compared to occasional cannabis smokers.
In view of this limitation, Lowe et al. (2009) monitored
33 chronic, daily cannabis smokers
- who abstained from drug use and resided on a secure unit
- under 24 h/day continuous medical surveillance for
- up to 30 days.
Urine specimens were quantified for total THC, 11- OH-THC, and THCCOOH (LOQ = 0.25 micrograms/L)
- after tandem Escherichia coli β-glucuronidase and alkaline hydrolysis.
This method efficiently hydrolyzes ester THCCOOH glucuronide linkages;
enzymatic methods do not completely hydrolyze THCCOOH glucuronides in urine,
- yielding only about 50% free drug,
while a combination of Escherichia coli β-glururonidase followed by 10N NaOH hydrolysis produced the most effective release of THC, 11-OH-THC and THCCOOH
from their glucuronides (Abraham et al. 2007).
Conversion of THC glucuronide to THC in (p.303) urine was 90.4%
- but the tandem hydrolysis method in plasma produced poor chromatography and could not be utilized (Schwilke et al. 2009).
Extended THC and 11-OH-THC excretion was observed by Lowe et al. (2009);
14 participants had measurable urine THC
- for at least 24 h after abstinence initiation.
- Seven of these were THC-positive for more than 3 days,
- 5 of these positive for 3–7 days,
- one for 12 days, and
- one for 24 days.
11- OH-THC and THCCOOH were detected in urine from one chronic frequent cannabis smoker for at least 24 days.
These data document long detection windows for THC and 11-OH- THC in urine, as well as THCCOOH in urine from chronic cannabis smokers.
Our new LCMSMS methods circumvent hydrolysis by directly quantifying THC, 11-OH-THC, THCCOOH, CBD, CBN, THC-glucuronide and THCCOOH- glucuronide
- in 1.0 mL whole blood or plasma (Schwope et al. 2011a) and
- 0.5 mL of urine (Scheidweiler et al. 2012).
These methods should facilitate investigations of the disposition and identity of urinary cannabinoids.
16.3 Cannabinoids in oral fluid
OF is a suitable specimen for monitoring cannabinoid exposure and has applications in
- driving under the influence of drugs (DUID) investigations,
- drug treatment,
- workplace,
- pain management and
- forensic drug testing, and
- in clinical trials (Bosker and Huestis 2009).
OF is
- easily and noninvasively collected,
- is gender neutral for a directly observed collection reducing adulteration potential,
- and basic drugs are present in OF in higher concentrations than in blood
These characteristics provide advantages over blood and urine testing.
Limitations include
- small sample volume,
- dry mouth after stimulant
- intake,
- potential contamination from smoking, and
- the need for high sensitivity analytical instrumentation.
The Substance Abuse Mental Health Services Administration (SAMHSA) in the US is currently evaluating OF for federally mandated workplace drug testing (Substance Abuse and Mental Health Services Administration 2011).
The European Union Roadside Testing Assessment (ROSITA) and DRUID studies demonstrated that OF was an acceptable matrix and identified collection devices that performed well (Houwing et al. 2013; Langel et al. 2008; Steinmeyer et al. 2001);
currently, many
European countries and Australia routinely utilize OF for DUID testing (Chu et al. 2012; Verstraete 2005).
Cannabinoid presence in OF primarily derives from THC depots in the mouth
- created by THC absorbed from THC-laden cannabis smoke (Huestis 2005).
The first OF specimen collected immediately after smoking contains large amounts of THC
- (approximately 5800 micrograms/L)
- that fell to concentrations near 80 micrograms/L by 0.3 h.
Initially, investigators believed that cannabis smoke was the only source of OF THC because
- cannabinoid metabolites could not be identified in studies using radiolabeled-THC or GCMS with an LOQ of 0.5 micrograms/L.
As scientists developed methods for THCCOOH at ng/L detection limits,
- THCCOOH concentrations were 10–142 ng/L in 21 of 26 OF specimens previously reported THC-positive (Day et al. 2006).
In the same year, Moore et al. (2006a, 2006b) validated the QuantisalTM collection device reporting 80% THCCOOH recovery, and
examined 143 OF specimens previously THC- positive.
- Ninety-five (66.4%) were positive for THC and THCCOOH,
- 14 (9.7%) for THCCOOH only,
- and 27 (18.8%) for THC only (THC LOQ = 1 micrograms/L; THCCOOH LOQ = 2 ng/L).
The physicochemical properties of THC and THCCOOH result in adherence of these cannabinoids to collection devices (Huestis et al. 2011).
THC recovery from nine collection devices ranged from 12.5–85.4% (Langel et al. 2008).
Addition of elution buffers to collection devices
- improved recoveries to greater than 90% in some collectors and
- stabilized labile OF analytes,
- potentially explaining inconsistencies in earlier reports (Bosker and Huestis 2009).
(p.304) OF collection and analytical procedures improved over time. A series of controlled cannabinoid administration studies characterized OF cannabinoids pharmcokinetics
- (Bosker and Huestis 2009;
- Coulter et al. 2012;
- Desrosiers et al. 2012;
- Lee et al. 2012a;
- Milman et al. 2010).
We measured THC, CBD, CBN, and THCCOOH disposition in
ten chronic cannabis smokers’ OF
- collected with a QuantisalTM device after each smoked a 6.8% THC cigarette (Lee et al. 2012a).
Cannabinoids were quantified by 2D-GCMS (LOQ = 0.5, 0.5, 1, 0.0075 micrograms/L, respectively).
OF samples (n = 86) were examined
- 0.5 h before and
- 0.25,
- 0.5,
- 1,
- 2,
- 3,
- 4,
- 6, and
- 22 h after smoking initiation.
Before smoking, four and nine participants’ OF samples were positive for THC and THCCOOH, respectively,
- but none were CBD or CBN positive.
More to come....
Cannabinoid Pharmacokinetics and Disposition in Alternative Matrices
16.2.3 Metabolism
THC metabolizes primarily to
- 11-OH-THC,
- THCCOOH and
- glucuronide conjugates.
THC hydroxylation at C9 by hepatic cytochrome
- P450 2C9,
- 2C19, and
- 3A4 enzymes
produces the equipotent metabolite, 11-OH-THC,
- originally thought to be the true psychoactive analyte.
More than 100 di- and tri- hydroxy, ketone, aldehyde, and carboxylic acid THC metabolites have been identified.
Significant 8β-OH-THC and lower 8α-OH-THC concentrations also have been detected.
Some important facts (Huestis 2005) regarding THC metabolism are:
◆ Plasma concentrations of 11-OH-THC following smoking are about 10% those of THC.
◆ Plasma concentrations of 11-OH-THC after oral ingestion are approximately equal to those of THC.
◆ THCCOOH-glucuronide is the principal Phase II metabolite.(p.302)
◆ Plasma THCCOOH concentrations are greater than those of THC 30–45 min after smoking and 1 h after oral ingestion (dronabinol) for occasional cannabis users.
◆ There is no significant difference in metabolism between men and women.
◆ There is large intra- and intersubject variability in the concentration profile of plasma THC and metabolites.
◆ THC is primarily metabolized in the liver but additional drug is metabolized in other tissues including brain, intestine and lung.
◆ After occasional cannabis users smoked 16 and 30 mg THC cigarettes, mean (range) plasma THCCOOH Cmax were
- 24.5 micrograms/L (15–54) and
- 54.0 micrograms/L (22– 101), respectively (Huestis et al. 1992).
The previously cited study by Schwope et al. (2011a, 2011b) described blood and plasma concentration time profiles for THC, 11-OH-THC, THCCOOH, CBD, CBN, THC-glucuronide and THCCOOH-glucuronide following smoking of a 6.8% THC cigarette (Fig. 16.2).
This study demonstrated that within hours THCCOOH-glucuronide, a more water soluble metabolite that is more readily excreted, is the major metabolite in blood and plasma.
THCCOOH-glucuronide can
be detected in blood for many hours,
- but can dissociate into free THCCOOH,
- especially when stored in blood outside the body at room temperature (Skopp and Potsch 2004).
16.2.4 Elimination
Within 5 days, 80–90% of a THC dose is excreted,
- primarily as
hydroxylated and carboxylated metabolites (Huestis 2005).
* More than 65% is excreted in feces, with
* approximately 25% in urine.
Of the many acidic urinary metabolites, THCCOOH glucuronide is primary,
while 11-OH-THC predominates in feces.
Some important facts (Huestis 2005) about THC elimination from the human body include the following:
◆ Elimination half-life for THC is nonlinear with a terminal half-life of about 4.1 days.
◆ Plasma THCCOOH and THCCOOH-glucuronide terminal elimination half-lives in frequent cannabis smokers were, respectively, 5.2 and 6.8 days and 6.2 and 3.7 days in occasional smokers.
◆ Urinary THCCOOH concentrations drop rapidly until approximately 20–50 micrograms/L, then are eliminated with a terminal half-life of about 3–4 days.
◆ The percent of a smoked THC dose excreted in urine over 7 days is about 0.54%.
◆ Detection times in urine after smoking a 3.55% THC cigarette with a 15 micrograms/L urine THCCOOH cutoff concentration is 2–5 days for occasional cannabis smokers
***but can extend to weeks in chronic daily cannabis smokers.
There is much less THC elimination data for chronic compared to occasional cannabis smokers.
In view of this limitation, Lowe et al. (2009) monitored
33 chronic, daily cannabis smokers
- who abstained from drug use and resided on a secure unit
- under 24 h/day continuous medical surveillance for
- up to 30 days.
Urine specimens were quantified for total THC, 11- OH-THC, and THCCOOH (LOQ = 0.25 micrograms/L)
- after tandem Escherichia coli β-glucuronidase and alkaline hydrolysis.
This method efficiently hydrolyzes ester THCCOOH glucuronide linkages;
enzymatic methods do not completely hydrolyze THCCOOH glucuronides in urine,
- yielding only about 50% free drug,
while a combination of Escherichia coli β-glururonidase followed by 10N NaOH hydrolysis produced the most effective release of THC, 11-OH-THC and THCCOOH
from their glucuronides (Abraham et al. 2007).
Conversion of THC glucuronide to THC in (p.303) urine was 90.4%
- but the tandem hydrolysis method in plasma produced poor chromatography and could not be utilized (Schwilke et al. 2009).
Extended THC and 11-OH-THC excretion was observed by Lowe et al. (2009);
14 participants had measurable urine THC
- for at least 24 h after abstinence initiation.
- Seven of these were THC-positive for more than 3 days,
- 5 of these positive for 3–7 days,
- one for 12 days, and
- one for 24 days.
11- OH-THC and THCCOOH were detected in urine from one chronic frequent cannabis smoker for at least 24 days.
These data document long detection windows for THC and 11-OH- THC in urine, as well as THCCOOH in urine from chronic cannabis smokers.
Our new LCMSMS methods circumvent hydrolysis by directly quantifying THC, 11-OH-THC, THCCOOH, CBD, CBN, THC-glucuronide and THCCOOH- glucuronide
- in 1.0 mL whole blood or plasma (Schwope et al. 2011a) and
- 0.5 mL of urine (Scheidweiler et al. 2012).
These methods should facilitate investigations of the disposition and identity of urinary cannabinoids.
16.3 Cannabinoids in oral fluid
OF is a suitable specimen for monitoring cannabinoid exposure and has applications in
- driving under the influence of drugs (DUID) investigations,
- drug treatment,
- workplace,
- pain management and
- forensic drug testing, and
- in clinical trials (Bosker and Huestis 2009).
OF is
- easily and noninvasively collected,
- is gender neutral for a directly observed collection reducing adulteration potential,
- and basic drugs are present in OF in higher concentrations than in blood
- due to ion trapping in the more acidic OF environment.
These characteristics provide advantages over blood and urine testing.
Limitations include
- small sample volume,
- dry mouth after stimulant
- intake,
- potential contamination from smoking, and
- the need for high sensitivity analytical instrumentation.
The Substance Abuse Mental Health Services Administration (SAMHSA) in the US is currently evaluating OF for federally mandated workplace drug testing (Substance Abuse and Mental Health Services Administration 2011).
The European Union Roadside Testing Assessment (ROSITA) and DRUID studies demonstrated that OF was an acceptable matrix and identified collection devices that performed well (Houwing et al. 2013; Langel et al. 2008; Steinmeyer et al. 2001);
currently, many
European countries and Australia routinely utilize OF for DUID testing (Chu et al. 2012; Verstraete 2005).
Cannabinoid presence in OF primarily derives from THC depots in the mouth
- created by THC absorbed from THC-laden cannabis smoke (Huestis 2005).
The first OF specimen collected immediately after smoking contains large amounts of THC
- (approximately 5800 micrograms/L)
- that fell to concentrations near 80 micrograms/L by 0.3 h.
Initially, investigators believed that cannabis smoke was the only source of OF THC because
- cannabinoid metabolites could not be identified in studies using radiolabeled-THC or GCMS with an LOQ of 0.5 micrograms/L.
As scientists developed methods for THCCOOH at ng/L detection limits,
- THCCOOH concentrations were 10–142 ng/L in 21 of 26 OF specimens previously reported THC-positive (Day et al. 2006).
In the same year, Moore et al. (2006a, 2006b) validated the QuantisalTM collection device reporting 80% THCCOOH recovery, and
examined 143 OF specimens previously THC- positive.
- Ninety-five (66.4%) were positive for THC and THCCOOH,
- 14 (9.7%) for THCCOOH only,
- and 27 (18.8%) for THC only (THC LOQ = 1 micrograms/L; THCCOOH LOQ = 2 ng/L).
The physicochemical properties of THC and THCCOOH result in adherence of these cannabinoids to collection devices (Huestis et al. 2011).
THC recovery from nine collection devices ranged from 12.5–85.4% (Langel et al. 2008).
Addition of elution buffers to collection devices
- improved recoveries to greater than 90% in some collectors and
- stabilized labile OF analytes,
- potentially explaining inconsistencies in earlier reports (Bosker and Huestis 2009).
(p.304) OF collection and analytical procedures improved over time. A series of controlled cannabinoid administration studies characterized OF cannabinoids pharmcokinetics
- (Bosker and Huestis 2009;
- Coulter et al. 2012;
- Desrosiers et al. 2012;
- Lee et al. 2012a;
- Milman et al. 2010).
We measured THC, CBD, CBN, and THCCOOH disposition in
ten chronic cannabis smokers’ OF
- collected with a QuantisalTM device after each smoked a 6.8% THC cigarette (Lee et al. 2012a).
Cannabinoids were quantified by 2D-GCMS (LOQ = 0.5, 0.5, 1, 0.0075 micrograms/L, respectively).
OF samples (n = 86) were examined
- 0.5 h before and
- 0.25,
- 0.5,
- 1,
- 2,
- 3,
- 4,
- 6, and
- 22 h after smoking initiation.
Before smoking, four and nine participants’ OF samples were positive for THC and THCCOOH, respectively,
- but none were CBD or CBN positive.
More to come....
mega-3 fatty acids. This has an inflammatory effect on the body. By consuming foods that have a high omega-3 content, like seafood and fish oil, you can bring this ratio back into balance.
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