addiction Flashcards
pharmacology of drugs of abuse: summarise the pharmacokinetics and pharmacology of the main drugs of abuse: cannabis, nicotine, cocaine, alcohol and opioids
4 commonest routes of administration for main drugs of abuse
snort (intra-nasal), eat/drink (oral), smoke (inhalation), inject (i.v)
intra-nasal administration: location and rate of absorption
mucous membranes of nasal sinuses; slow absorption (diffuses into venous system)
oral administration: location and rate of absorption
GI tract; very slow absorption
inhalation administration: location and rate of absorption
small airways and alveoli; very rapid absorption (minimal resistance to flow and already in pulmonary circulation)
i.v administration: location and rate of absorption
veins; rapid absorption
4 pharmacological classifications of drugs of abuse
narcotics/painkillers, depressants (‘downers’), stimulants (‘uppers’), miscellaneous
examples of narcotics/painkillers
opiate-like drugs e.g. heroin
examples of depressants
alcohol, benzodiazepines (valium), barbiturates
examples of stimulants
cocaine, amphetamine (‘speed’), caffeine metamphetamine (‘crystal meth’), nicotine
examples of miscellaneous (have other properties)
cannabis, ecstasy (MDMA)
forms of cannabis
cannabis/marijuana, hashish/resin (trichomes - glandular hairs), hash oil (solvent extraction)
number of compounds and cannabinoids in cannabis
> 400 compounds, >60 cannabinoids (n glandular hairs)
2 primary cannabinoids of cannabis, and onset of cannabis
cannabidiol and THC (most powerful); seconds->minutes
dosing in cannabis plant: reefer (60s-70s) vs skunkweed/netherweed (21st century) and relevance
10mg THC vs 150-300mg THC; farmed to increase amount of THC in plant, so more powerful effect (if increase dose, hit ceiling of positive symptoms, but increasing risk of negative effects - cannabidiol moderates effects of THC, but with increased THC at expense of cannabidiol, elevation of negative effects)
administration of cannabis bioavailablity (% into bloodstream)
5-15% oral (delayed onset and slow absorption as fair amount of first pass metabolism by liver before entering blood stream), 25-35% inhalation (exhale about 50% back out again, and that 50% remaining must be deeply inhaled)
distribution of cannabis
diffuses freely from blood into organs, but overtime intensive accumulation occurs in less vascularised tissues and finally slowly accumulates in poorly perfused fatty tissues (long-term storage site as very lipid-soluble; reversible so slowly diffuses back into blood)
upon cannabis administration, what therefore builds up in fatty tissue
fatty acid conjugates of 11-OH-THC
concentration ratios of THC between fat and plasma
10^4 : 1
metabolism of cannabis: phase 1 metabolite location and name
liver to 11-hydroxy-THC (more potent than THC); liver can only conjugate (phase 2) so much per unit time
excretion of cannabis
65% GI tract into bile and faeces, 25% urine
what does cannabis undergo if excreted in bile as lipid-soluble
enterohepatic recycling
describe and explain correlation between plasma cannabinoid concentration and degree of intoxication
poor, as can measure plasma THC, but no info on 11-hydroxy-THC levels, levels in fat or enterohepatic recycling
describe cannabinoid diffusion to brain
structural fat in brain, so cannabinoids diffuse into and build up in brain, so 7-8x more THC in brain than blood (blood mainly has phase 2 conjugated form)
tissue half life of cannabis, and how long after smoking a cannabis cigarette will the effects persist in the body (remains in adipose tissue)
tissue half life of 7 days, but due to remaining in adipose tissue, effects persist for 30 days