Symposium 3 - Addictions Psychiatry Flashcards
Define tolerance.
Reduced responsiveness to a drug caused by previous administration
Give examples of drugs that can develop tolerance?
Opioids
Ethanol
Barbiturates
Benzodiazepines
What is dispositional tolerance?
Less drug reaches active site
What is pharmacodynamic tolerance?
Drug has less action at active site
What can cause dispositional tolerance?
decreased rate of absorption
increased rate of metabolism
increased rate of excretion
What can cause pharmacodynamic tolerance?
Down-regulation of internalisation of drug receptors
Reduced signalling
What can development of tolerance lead to?
Withdrawal symptoms –> increased response
from homeostasis compensatory mechanism
What is the withdrawal phenomenon?
Withdrawal effect of drug usually reverse of acute effect
Give an example of an acute vs withdrawal effect of a drug.
Opioid: acute = constipation, withdrawal = diarrhoea
Cocaine: cocaine = elevated mood, withdrawal = depressed mood
What is the reward pathway?
Ventral tegmental area –> nucleus accumbens –> prefrontal cortex
Dopamine = neurotransmitters
Causes sensation of pleasure/reward
Give examples of drugs of abuse that tap into reward pathway and increase dopamine?
Heroin -> increases firing rate of dopaminergic neurons
Amphetamine -> increases dopamine release
Cocaine -> inhibits dopamine uptake
Alcohol
What are the two distinct components of drug dependence?
- Physical dependence (consequence of tolerance)
2. Psychological craving (from reward pathway stimulation)
What is the most addictive drug?
Heroin
Name two classes of stimulant drugs?
Cocaine
Amphetamine
What is cocaine made from?
Coco plant