Lecture 35

Question 1

What are the different forms of cannabis?

Answer 1

Marijuana/ganja which is the dried flowers and top leaves of female plant
Kief which is the sticky resinous bits of plants
Hashish which is pressed keif into a hard concentrated lump
Hash Oil which is an ethanol extract from cannabis
Resin which is the tar like left overs

Question 2

What are the general clinical pharmacological factors of cannabis?

Answer 2

The hemp plant (cannabis sativa) produces a resin containing about 60 cannabinoids
Delta9 tetrahydrocannabinol (9THC) is the principal active agent
The THC content of marijuana varies greatly

Question 3

What is the mode of action of cannabis?

Answer 3

There are two forms of the cannabinoid receptor CB1, CB2
CB1 is located in the brain and peripheral tissue and mediates most of the effect
CB2 is found on receptors of immune cells, membrane bound G-linked receptors for which the endogenous ligand is anandamide
Cannabinoids facilitate activity of the brain reward centre
The effects depend on the dose, the individual and the settings
Low dose results in a mixture of stimulatory and depressant effect
High dose results in mainly depressant effect

Question 4

What are the objective acute effects of cannabis?

Answer 4

Elevated heart rate
Conjuctival reddening
Decreased muscle strength
Increased food intake
Impairment in memory, cognition and skill performance (although feel confident and highly creative)

Question 5

What are the acute subjective effects of marijuana?

Answer 5

Initial euphoria
Gradual onset of sedation
Altered time perception
Difficulty concentrating
Hallucinations
Depersonalization
Anxiety, paranoia
Nausea and vomiting

Question 6

What are the pharmacokinetics of cannabis if it is smoked?

Answer 6

There is rapid delivery to the blood and therefore the brain with peak plasma values at the end of smoking falling to low values within 2 hours
THC is lipophilic and rapidly taken up by body lipids resulting in low elimination of drug which outlasts active effects
Blood concentrations of THC do not correlate well with effect
Presence of THC in urine does not always mean recent usage
Metabolism of THC is mainly in the liver by CYP450

Question 7

What are the metabolites of cannabis?

Answer 7

Produced by CYP450
11-hydroxy-THC is active but remains at very low levels resulting in it probably having little effect
Major metabolite is 11 carboxy-THC which is inactive but remains at high concentrations and is usually what is measured

Question 8

What are the effects of tolerance in cannabis users?

Answer 8

Tolerance will develop to most of the effects resulting in the acute cognitive and psychomotor impairment being negligible

Question 9

What are the withdrawal symptoms of cannabis?

Answer 9

Anxiety
Irritability
Insomnia and disturbed dreams
Poor appetite
Nausea
Muscle aches
Restlessness
These symptoms typically commence on day 1 and peak on day 2-3`

Question 10

What are the potential therapeutic uses of cannabinoids?

Answer 10

Conditions with spasticity (spinal cord injury and multiple sclerosis)
Movement disorders (Huntingtons chorea, tourettes syndrome, dystonias, parkinsons disease)
Nausea
Appetite stimulation
Conditions with pain (neuropathic pain)
Epilepsy
Glaucoma