PHAR Mod 3 Section 3

What does the term cannabis refer to?

refers to drug-containing forms of the hemp plant, cannabis sativa, which is an herbaceous annual.

What is the name of the chemical compounds found in cannabis sativa

cannabinoids (CB)

THC → most potent psychoactive agent in cannabis and accounts from most, but not all, of the psychoactive effects

Two classification of Cannabis

Pharmacologically

• CNS depressant, euphoriant, and hallucinogen 

legally 

• in 2018 cannabis became legel in canada 

how is cannabis typically administered 

• smoked or inhaled 

• vaping or through oral consumption 

the mechanism of action of cannabis

• THC binds specifically to receptors located in the brain and spinal cord called type 1 cannabinoid receptors (CB₁)

• the CB₁ when activated inhibits the release of excitatory neurotransmitters

• this explains the reduction in cognitive function and CNS depressant effects seen with THC

What are the two types of cannabinoid receptors and where are they found

CB1 receptors

• in the brain

• cerebral corext

• hippocampus

CB2 receptors

• outside the CNS

• lymphocytes

what effect do CB1 receptors in the cerebral cortex have?  

• mediates the distortion of time, colour, sound, and taste 

• mediates the decrease in cognitive function and concentration 

what effect do CB1 receptors in the hippocampus have

may account for changes in memory and learning

what explains the relative non-lethality of cannabinoids

the fact that there are no CB1 receptors present in the brain stem

thus cannabinoids do not depress respiration, explaining the relative non-lethality of the drug

CB2 binding to lymphocytes is thought to be responsible for what properties of THC

for the immunosupressive properties of THC

role of THC in cannabis 

THC is the primary component in cannabis causing psychoactive effects 

2 tpes of Absorption of THC + its rate of absoprtion

THC is commonly inhaled or ingested

• inhaled

  • rapid and the onset of action is almost immediate

  • effect lasts 3-4 hours

• Ingested

  • absoprtion occurs slowly and is incomplete

  • onset of action is delayed 30-60min

  • effect is less than that from smoking cannabis

distribution of THC

• THC rapidly distributes throughout the body, especially to tissues with high blood perfusion such as the lung, heart, brain, and liver 

• THC also rapidly crosses the placenta. These processes are much slower following oral ingestion given the slow absorption of this route of administration 

• THC is highly soluble and over time will be stored in adipose tissues

THC metabolism

metabolized slowly

• those consuming cannabis may test positive for the metabolites weeks after use has stopped

THC excretion

THC has a half-life of approximately 30 hours

elimination of THC from adiposte tissue may take longer

early effects of cannabis on the CNS

• relaxation and drowsiness

• a feeling of well-being and euphoria

• impaired motor coordination

• increased appetite

short-term effects of cannabis use on the cardiovascular system include

• increased heart rate

• inreased blood flow to the extremities

• postural hypotension

  • acute low blood pressure when standing or sitting up wheich can cause dizziness or fainting

short term effects of cannabis use on the GI tract include

• increased appetite

• dryness of the mouth and throat

other short-term effects of cannabis use include

• reduction of sex drive in males as THC may reduce testosterone levels

• disruption of the ovarian cycle by THC in females

• a hangover, similar to that of alcohol, when the drug wears off

psychological effects of long term cannabis use

• loss of short-term memory 

• lack of concentration 

• loss of ability in abstract thinking 

• loss of ambition and emotional flatness 

Cardiovascular effects of cannabis use

• usually reversible

  • changes in blood pressure do not appear to be serious

  • increase in heart rate

respiratory effects of long term cannabis use

• bronchitis

• asthma

• sore throat

• chronic irritation and damage to membranes of the respiratory tract

• increased chances of lung cancer and chronic obstructive pulmonary disease

fertility effects of long-term cannabis use

males: decreased sperm count

females: follicle stimulation hormone and luteinizing hormone to be reduced

pregnancy: THC freely crosses the placenta and can cause developmental delays leading to cognitive deficits, impulsiveness and inattention, and hyperactivity

Medical use of cannabis 

• Cannabis is not a health canada approved therapeutic product 

• however, healthcare practitioners may authorize the use of cannabis for the relief of a number of symptoms which have not responded to conventional medical treatments 

  • prevention of nausea and vomiting associated with anticancer drus

cannabis potential for misuses and SUD

low to moderate, as euphoria and reinforcement are less compared to some other drugs (eg. cocaine). the inherent harmfulness of cannabis is also low

Cannabis tolerance

• tolerance occurs to

  • the psychoactive properties of THC

  • the effects on the cardiovascular system

  • the impairment of performance and cognitive function

Cannabis withdrawal

upon termination of long-term high dose, a mild withdrawal syndrome occurs 

• sleep disturbances

• irritability 

• loss of apetite

• nervousness

• mild agitation 

• upset stomach 

• sweating 

cannabis addiction

addiction develops as a persistent craving for the drug.

the risk of addiction is more evident in those who use cannabis to control psychological stress