Absorption, Distribution, and Elimination of Cannabis

• Author: James G. Wigmore
• Pages: 1-36

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 1

Absorption, Distribution, and Elimination

of Cannabis

The absorption, distribution, and elimination of a drug such as tetra-

hydrocannabinol (THC) is commonly referred to as the pha rmacokin-

etics of the drug, and it is what the body does to the dr ug: how THC is

absorbed into the body, mainly by smoking or vaping of cannabis, but

also by oral ingestion; how it is distributed via the blood to the various

fat tissues of the body; and f‌inal ly, elimination (metabolized mainly by

the liver) and it is eliminated in a large proportion by the feces. In com-

parison, alcohol is water soluble and little is excreted via the feces.

Due to its fat solubility, initially THC is eliminated very rapidly as

it is redistributed throughout the body to the various fat tissues, and

then, after several hours, THC is eliminated at a slow rate, which may

take several days. As a lcohol is water soluble, it does not have a biphasic

elimination and is removed from the body at a f‌ixed, consta nt rate in a

matter of hours.

1.01 ABSORPTION

Absorption is how the drug gets into the body. THC is most rapidly ab-

sorbed by smoking or vaping the cannabis plant material, concentrates,

or dabs. The peak blood THC concentrations are reached within min-

utes after smoking, whereas after ora l ingestion, peak blood THC con-

centrations usually occu r in sixty to ninety minutes after ingestion, but

it may take longer ().

Oral ingestion of cannabis results in a three to four times greater

concentration of the active metabolite -OH-THC in the blood than

  Wigmore on Cannabis

Reference Number: 

occurs after smoking (), which may explain t he more severe reac-

tions that occur with ora l ingestion.

Signif‌icant blood THC concentrations cannot be obtained by pas-

sive inhalation of cann abis smoke unless there is no ventilation in the

room and a large amount of cannabis is smoked (). Under such

extreme conditions, it may be argued that absorption is no longer pas-

sive, but may be deliberate. The higher the blood THC concentration the

shorter the time lapse has occur red since smoking (). Vaporization

of cannabis has less respir atory symptoms (such as coughing) and is t he

most popular method of canna bis administration in medical mar ijuana

user s (,  ).

CBD does not af‌fect the pharmacokinetics of T HC ().

Reference Number: 10101

, .., .. , .. , .. , . , . ,

 . . “Non-Smoker Exposure to Secondhand Smoke. I

Urine Screening and Conf‌irmation Results.” Journal of Analytical Toxi-

cology, : –,  ( tables,  f‌igures,  references)

Abstract: Six experienced marijuana smokers smoked cannabis ciga-

rettes (. percent and . percent THC) in a sealed room beside six

non-smokers, with and without ventilation. The subjects wore goggles

to prevent eye irritation, as a considerable amount of smoke was gen-

erated. The subjects were exposed to the smoke for one hour. At a 

ng/mL THCCOOH cutof‌f, all screening tests were negative for non-

smokers except for one, which was a presumptive result. The mean TH-

CCOOH urine concentration was much lower with ventilation.

Cannabis potency and room ventilation were demons trated to be two

major factors in determining the exte nt of cannabis smoke exposure

to non-smokers residing in close proximity to smokers. Shor t term ex-

posure to high intensity smoke from combusted cannabis resulted in

non-smoker inhalation of sucient amounts of THC to produce posi-

tive presumptive urine tests by immunoassay with a  ng/mL cutof‌f

concentration, but only a single positive occurred at higher cutof‌f con-

centrations ( ng/mL). GC-MS analysis of presumptive positives con-

f‌irmed the presence of THCCOOH at >  ng/mL in some specimens.

Chapter 1: Absorption, Distribution, and Elimination of Cannabis  

Reference Number: 

Reference Number: 10102

, .., .. , .. , .. , . , . -

,  . . “Nonsmoker Exposure to Secondhand Cannabis

Smoke. III Oral Fluid and Blood Drug Concentrations and Corres-

ponding Subjective Ef‌fects.” Journal of Analytical Toxicology, : –

,  ( tables,  f‌igures,  references)

Abstract: Six experienced cannabis u sers smoked marijuana ciga rettes

(. percent and . percent THC) for one hour with or without venti-

lation in the same sealed room as six non-smokers. Oral f‌luid, whole

blood, and subjective ef‌fects were determined at various points in time

after exposure to secondhand smoke. OF was analyzed by ELISA ( ng/

mL cuto) and LC/MS/M S (LOQ  ng/mL THC). Blood was analyzed by

LC/MS/MS. There was a subjective report of pleasant drug ef‌fect at the

session of high THC with no ventilation in the six non-smokers.

This study demonstrated that extreme exposure to environmental can-

nabis smoke by non-smokers situated in close proximity to smokers led

to deposition of THC in oral f‌luid. Oral f‌luid specimen s for non-smok-

ers in the two sessions conducted without ventilatio n tested positive

by IA ( ng/mL cuto) and were conf‌irmed for THC by LC-MS-MS (

ng/mL) for up to three hours following cessation of exposure. In the

third session of this study, conducted with ventilation that simulated air

conditioning, some initial positive tests occurred but th e number was

substantially diminished. Impor tantly, no THCCOOH was detectable

in oral f‌luid by LC-MS-MS at the LOQ (. ng/mL) in any exposure

sessions for non-smokers.

Reference Number: 10103

, ., . , . , . , .. ,  .. -

. “Cannabinoids in Blood and Urine after Passive Inhalation of

Cannabis Smoke.” Journal of Forensic Sciences, : –,  (

tables,  f‌igure,  references)

Abstract: Three female and seven male control subjects (ages  to 

years) were divided into two groups. One group was exposed to passive

inhalation of hashish by three subjects who smoked two hashish ciga-

rettes over thirty minutes. The other group was exposed to the passive

inhalation by two subjects who smoked six marijuana cigarettes each