Cannabis Flashcards
What plant is Cannabis derived from?
Hemp - Cannabis Sativa. Also used for rope, cloth and paper and the seeds are used for birdfeed.
What is the psychoactive agent in cannabis?
Delta9 Tetrahydocannabinol (THC)
Where is THC concentrated?
In the sticky resin secreted by the flowing tops of female plants.
In what three main forms is cannabis obtainable?
- Marijuana (dried and crumbled leaves, smoked)
- Hashish (solid, prepared from resin, different concentrations)
- Hash oil (reduced alcoholic extract, single drop placed in joint)
Why does the THC content in cannabis vary?
Due to sinsemilla - if pollination is prevented it increases potency.
In what ways was cannabis first used?
2700 BC - Medical use in China
2000 BC - Religious use in India
1000 AD - Hashish use in Arab world
When were the Marijuana Tax Act and the first laws legalising medical use?
1937 and 1996, respectively.
How was cannabis use introduced into the west?
From Egypt by Napoleon’s soldiers.
Name two notable ‘hashish eaters’ found by Mareau.
Victor Hugo and Alexandre Dumas.
Approximately how much cannabis does a typical joint contain?
0.5-1g
if THC content 4% = 40mg THC/joint
How is THC absorbed and what percentage of it is absorbed, when smoking a joint?
Burning marajuana = vaporisation = absorption = blood plasma
20% of THC absorbed, can be increased by breath holding (Black et al, 1998 7 vs. 15s hold)
After peak levels of THC in the blood are reached, how do they fall?
Through metabolism in liver and fat storage.
What is the half-life of THC, and how long can it be detected in urine for?
20-30 hours and 2-3 weeks respectively.
What did Devane et al (1988) do?
Identified the cannabinoid receptor (CB1), agonised by THC.
Where are cannabis receptors active?
In areas consistent with behavioural effects, e.g. the hippocampus for spatial memory (also substantia nigra and globus padillus)
What is the antagonist for CB1 receptors?
SR 141716
According to Iversen (2000), what are the acute behavioural effects of cannabis?
- The ‘buzz’ (brief) - light-headedness, dizziness, tingling in extremities due to increased blood flow and HR.
- The ‘high’ - euphoria, exilharation, disinhibition (the giggles)
- Being stoned (large amount) - calm, relaxed, dream-like state.
What psychological changes are involved in being ‘stoned’?
- A calm, relaxed, dream-like state.
- Sensations of floating, enhanced visual and auditory perception
- Slowing of the perception of time
- Changes in sociability (increases or decreases)
What are the physiological effects of cannabis?
- Increased blood flow to skin = warmth
- Increased HR = pounding pulse sensation
- The ‘munchies’.
Who has demonstrated the munchies, and what mechanisms is it caused by?
- In humans: Foltin et al (1988), in rats: Williams et al (1998)
- Caused by increase in palatability (Williams and Kirkham, 2002, rats) and hyperphagia (abolished by CB1 antagonist, Williams & Kirkham, 2002)
What did Heustis et al (2001) find when studying how the effects of marijuana are attenuated by a CB1 antagonist?
Had antagonist and placebo group, both given a joint.
In antagonist group, feeling high and stoned was reduced (self-report q.aire), as was HR, but effects weren’t abolished.
What do Heustis et al (2001)’s findings suggest?
Either a stronger dose of CB1 antagonist was necessary, or another mechanism mediates effects.
What did Agurell et al (1986) find?
That route of administration has a substantial effect on blood plasma levels of THC after smoking a joint or oral consumption. (Oral slower to peak but lasted longer).
Why do smokers not report a peak until after the joint has been finished?
- Brain and plasma concentrations are not yet at equilibrium
- THC isn’t fully metabolised.
