Drug misuse and addiction Flashcards
what are the two mechanisms are responsible for addiction of a drug?
dependence due to tolerance of the drug
psychological craving due to activation of the reward centre
describe the pathway of the reward centre.
neurones pass from the ventral tegmental area to the nucleus accumbens to the pre-frontal cortex
what are the mechanisms of tolerance?
less drug reaching active site;
- increased metabolism of drug
- increased excretion of drug
- less drug absorbed
drug has less action at the active site
- fewer receptors
- less efficient drug receptors
how does heroin, cocaine and amphetamines impact the reward centre and why does this impact addiction?
activation of the reward centre leads to cravings
heroin increases firing of dopaminergic neurones
cocaine decreases uptake of dopamine
amphetamines increase the release of dopamine
what symptoms may someone experience from withdrawal from cocaine?
depression irritability agitation craving hyper somnolence hyperphagia
what symptoms may someone experience from withdrawal from opiates?
diarrhoea muscle pain and cramps craving nausea insomnia dilated pupils piloerection increase in salivary and lacrimal secretions
what are the effects from opiates such as heroin?
euphoria
analgesia
drowsiness / sleep
what are the positive effects from cocaine?
euphoria alertness lack of judgement energy decrease need for food and sleep
what are the negative consequences from cocaine?
potent vasoconstrictor - ENT problems paranoid psychosis toxic confusion seizures respiratory failure hypertension stroke (cerebrovascular accident) arrhythmias
what are the negative consequences from heroin?
decreased sympathetic outflow - hypotension, bradycardia
hypothermia
respiratory depression
cough reflex depression
constipation
sensitisation of the labyrinth with nausea and vomiting
what’s the difference between the effects of amphetamines and cocaine?
amphetamines have the same effects as cocaine but last longer
what are the main negative consequences of heavy amphetamine use?
toxic confusion with convulsions
amphetamine psychosis
what are the methods of use of heroin?
smoking
injecting
snorting
what are the methods of use of cocaine hydrochloride and crack cocaine?
crack - smoked
cocaine powder - snorted
coca leaves - chewed or brewed
what are the features of opiate overdose?
respiratory arrest with a pulse
pin point pupils - fixed and unreactive to light
snoring giving way to shallow respiration (< 8 breaths/min)
bradycardia and hypotension
reduced consciousness / coma
