Addiction Symposium Flashcards
What are the 2 distinct mechanisms implicated in why we use drugs?
- Tolerance (the basis of physical dependence)
- Reward centre (the basis of psychological craving)
Tolerance
reduced responsiveness to a drug caused by previous administration
What is tolerance an example of?
homeostasis
What does tolerance develop in response to?
many types of drug
- opioids, ethanol, barbiturates, benzodiazepines
What are the 2 mechanisms of tolerance?
dispositional tolerance: less drug reaches the active site
pharmacodynamic tolerance: drug has less action at the active site
What is the result of dispositional tolerance?
- decreased rate of absorption
- increased rate of metabolism to inactive metabolites
- decreased rate of metabolism to active metabolites
- increased rate of excretion
What is the result of pharmacodynamics tolerance?
- fewer drug receptors
- less efficient drug receptors
What may the development of tolerance lead to?
Withdrawal symptoms
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What is the withdrawal phenomena?
the reverse of the acute effect of the drug
What are the acute and withdrawal effect of opioids?
Acute
-Constipation
Withdrawal effect
-Diarrhoea
What are the acute and withdrawal effect of barbiturates?
Acute
-Anticonvulsant
Withdrawal effect
-Convulsions
What are the acute and withdrawal effect of cocaine?
Acute
-Elevated mood
Withdrawal effect
-Depressed mood
Describe the reward pathway.
- neurones project from the ventral tegmental area to the nucleus accumbens & prefrontal cortex
- when VTA neurones are stimulated they release dopamine is released
- this causes a sensation of pleasure/reward
Why has the reward pathway evolved?
- reward pathway activated by eating, drinking and sex
- encourages ‘healthy’ behaviours that lead to propagation of your genes
Give examples of some drugs of abuse that tap into the reward pathway and increase dopamine levels
- heroin (increases firing rate of dopaminergic neurones)
- amphetamine (increases dopamine release)
- cocaine (inhibits dopamine uptake)
- alcohol
Give 2 examples of stimulants.
- Cocaine
- Amphetamine
What has cocaine be used for in the past?
ENT surgery
What is the most potent natural stimulant?
Cocaine
How can cocaine be taken?
cocaine (powder)
crack cocaine is smoked (cocaine + base + purified)
How does the means of consumption affect the effects of cocaine?
depends on dose and rate of entry to the brain
- smoking: almost immediate
- injecting 15 to 30 secs
- snorting: 3 to 5 mins
- the effects of crack smoking are very intense but quickly over ( 15 mins)
What are the effects of cocaine?
- Stimulant and euphoriant
- Increased alertness and energy
- Increased confidence and impaired judgement
- Lessens appetite and desire for sleep
- Damage to nose and airways
- Convulsions with resp failure
- Cardiac arrhythmias and MI
- Hypertension and CVA
- Toxic confusion
- Paranoid psychosis
What are the withdrawal effects of cocaine?
- Depression
- Irritability
- Agitation
- Craving
- Hyperphagia
- Hypersomnia
What is the general amphetamine used?
Amphetamine sulphate