Biomedical Engineering Reference
In-Depth Information
5.3
Cannabinoids
The cannabinoids are a class of psychoactive substances contained both in
Cannabis
and
Echinacea
plants. The first reliable evidence of the effects of drugs derived
from cannabis is a compendium of Chinese medicine (a herbarium), dated 2700 BC ;
today it has become very common in many parts of the world.
Phytocannabinoids are natural compounds present in
Cannabis sativa
, respon-
sible for the pharmacological and toxicological properties of this plant. About 70
compounds belong to this class, the most important are D
9
-tetrahydrocannabinol
(THC), cannabinol (CBN), and cannabidiol (CBD).
THC is considered the most pharmacologically active cannabinoid of Cannabis
[
30
] and is used as a reference substance for estimating the psychotropic power of
the various preparations of this plant. THC is rapidly absorbed in large amounts and
passes into the blood stream, and due to its lipophilicity it can spread throughout the
body and penetrate the brain.
Derivatives of cannabis are hashish, which consists of a resin produced by the
inflorescences (6-10 % THC), marijuana, which is in the air-dried leaves, flowers,
and the stem (2-5 % THC), and hashish oil that looks like a viscous liquid, like tar,
obtained by extraction with organic solvents (15-60 % THC). These derivatives are
usually smoked.
5.3.1
Pharmacodynamics
There are specific binding sites for cannabinoids, whose endogenous antagonists
belong to the class of endocannabinoids. The human organism produces endocan-
nabinoids from long-chain polyunsaturated fatty acids, they bind to cannabinoid
(CB) receptors and activate them. The CB receptors and endocannabinoids consti-
tute the endocannabinoid system [
31
]. THC binds to both types of receptors:
CB1 and CB2. The absence of cannabinoid receptors in the brain stem, the seat of
the centers of respiration and other vital functions, explains the low toxicity of
cannabinoids.
5.3.2
Effects
Activation of CB receptors by phytocannabinoids such as THC can cause a multi-
tude of effects such as euphoria, anxiety, altered time perception, loss of concentra-
tion, and panic attacks. The most commonly researched ones are feeling of
well-being, euphoria, and relaxation. THC produces an increase in heart rate, blood
pressure, and body temperature (dose-dependent effects). It is also possible to expe-
rience dry mouth, increased hunger, and pain reduction. Very high doses of cannabis
can cause anxiety, panic, or result in psychotic episodes.
