Drugs of Abuse: Drugs and Cannabis Flashcards
(48 cards)
what system in the brain enables euphoria?
dopaminergic neurones from the VTA stimulate the release of dopamine into the NAcc in the reward system
what are the methods of drug administration?
o Intranasal (via mucous membranes in nasal sinuses) – slow absorption.
o Oral – very slow absorption.
o Inhalational – rapid absorption.
o Intravenous – rapid absorption.
what is the fastest route of administration to the brain?
inhalation- pulmonary circuit is very short
IV has to do the systemic circuit before reaching the brain
what are the main classification of drugs?
- narcotics (painkillers)
- depressants
- stimulants
- miscellaneous
examples of narcotics
opiate-like drugs e..g heroin
examples of depressants
alcohol
benzodiazepines (valium)
examples of stimulants
cocaine amphetamines caffeine methamphetamines nicotine
example of miscellaneous drugs
cannabis
ecstasy
these drugs have effects from multiple classes
what is the order of onset of euphoria in ascending order based on administration
oral< intranasal < IV, inhalation
what are the components of cannabis?
- cannabis sativa is the plant
- hashish/resin is the trichomes (glandular hairs that contain the highest concentration of THC)
- hash oil is the solvent extract
how many compounds in cannabis?
over 400, >60 of them being cannibinoids
what is the most potent cannabinoid?
delta 9-THC
what produces the positive effects of cannabis smoking?
the inclusion of cannabidiol may regulate the negative effects of delta 9 THC
how has dosage of THC changed over time?
Doses in 60’s and 70’s was ~10mg THC
Now it is 150-300mg of THC.
Potency has increased over the years; delta9-THC has increased, so has cannabidiol. Here, the negative effects are more pronounced
what are the route of administration of cannabis?
o Oral – 5-15% THC delivered.
o Inhalation – 25-25% THC delivered. Must be breathed in deeply
why is THC delivery lower when cannabis is taken orally?
delayed onset due to slow absorption with first pass metabolism
how does cannabis accumulate and leave?
- slowly accumulates in the body as it is very lipid soluble
- builds up fatty acid conjugates.
- Accumulation in poorly perfused fatty tissue with chronic use
takes 30 days for effects to cease
how is cannabis metabolised?
THC converted to a more potent molecule: 11-OH THC, a phase 1 metabolite
11-OH THC is more potent than delta 9 THC
how is cannabis excreted?
- GIT 65%:enters bile and is enterohepatically recycled due to its lipid solubility
- urine 25%
what is the difference in concentration of THC in the brain and the blood?
what is the effect of this?
THC is more concentrated in the brain (which is very fatty) compared to the blood due to the lipid soluble property of cannabis
therefore there is a poor correlation between plasma cannabinoid and degree of toxicity
what receptors do cannabinoids bind to ? where are they located?
- CB1 receptors in the brain: Hippocampus, cerebellum, cortex and basal ganglia
- CB2 receptors in the periphery: immune cells
what type of receptor is CBr?
inhibitory GPLR linked to adenylate cyclase
depresses cell activity
what is the endogenous version THC that normally binds to the CBr?
anandamide
result of fatty acid amide hydrolase inhibition
how does binding to CBr lead to euphoria?
binding of Cb1 receptors on GABA neurones inhibits the release of GABA. This has a disinhibition effect on the VTA neurone releasing dopamine. The inhibition on dopamine release is reduced so more dopamine is released
