Lecture 15 - Cannabis Flashcards
What is cannabis?
genus of flowering plant. contains many bioactive compounds, but most studied are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the primary psychoactive compound in cannabis
What are cannabinoids
class of chemical compounds that act at the cannabinoid receptors
What is bioavailability?
fraction of an administered drug that reaches effectors
What is the absorption of smoking cannabis?
-rapid and efficient delivery from lungs to brain
- bioavailability of smoked THC is 25%, reaching peak plasma concentration in 6-10 minutes
What is the absorption of ingesting cannabis?
bioavailability around 6%, time to peak plasma concentration is 2-6 hours
What is the distribution of THC
- highly lipophilic so rapidly taken up by tissues with high blood flow including heart, lungs, brain and liver
- tissues with less blood flow accumulate THC more slowly and release it over a longer period of time
- THC stored in fat in chronic, frequent cannabis smokers can be released into the blood for days
What is the metabolism and elimination of THC
- THC metabolism occurs mostly in the liver by cytochrome P450 2C9 enzyme producing the metabolites 11-OH- THC and THC-COOH
- within 5 days, 80-90% is excreted, primarily as metabolites, 65% in feces and 25% in urine
- can detect THC in urine 2-5 days for low dose THC, but can extend to weeks in chronic daily cannabis smokers
What are cannabinoid receptors
inhibitory G-protein coupled receptors (Gi coupled)
What are the two flavours of cannabinoid receptors
CB1 and CB2
How do CB receptors affect cAMP
decrease cAMP which inhibits influx of calcium in the firing neuron and inhibits neurotransmitter release
What is THC at CB1
partial agonist
What are CB1 receptors?
- are among the most abundant GPCRs
- found in brain, peripheral organs and peripheral nerves
What are CB2 receptors
mostly distributed on immune cells
What are acute effects of THC?
panic attacks, severe anxiety, psychosis, paranoia, convulsions, hyperemesis. These are rare and usually associated with high doses of THC
What are prenatal effects of THC?
cannabis use may lead to neuroanatomical and behavioural changes in offspring. fetal growth affected (particularly neurodevelopment), but dose-response relationship not identified
What causes lung cancer
smoked cannabis
What is effect of THC on driving
- increase the risk for being in a motor vehicle accident. THC impairs perception, psychomotor performance, cognitive functions and affective functions. Decreased reaction time
What is psychological dependence
compulsive drug-seeking behaviour in which the individual uses the drug receptively for personal satisfaction, often in the face of known risks to health
What is physiological dependence
revealed when withdrawal of the drug produces symptoms and signs that are frequently opposite of those sought by the user
What is cannabis withdrawal
-relatively mild and short-lived
- symptoms of restlessness, irritability, mild agitation, insomnia, nausea, and cramping.
- may be worse in chronic, long-term users, and may contribute to continued drug use
What is addiction
defined as the inability to control the use of legal or illegal substances despite negative consequences
- diagnosed by 11 diagnostic criteria
What are synthetic cannabinoids
a manufactured compound whose properties imitate those of the active constituents of cannabis
Why are synthetic cannabinoids better
- increased specificity
- decreased off target effects
- easier dosing
- better controlled studies
What is nabilone?
synthetic analog of THC
