Addiction Flashcards
What is the definition of tolerance?
Reduced responsiveness to a drug caused by previous administration
What types of drugs cause an addiction response?
Many drug
opioids
ethanol
barbiturates
benzodiazepines
What is dispositional tolerance?
Less drug reaches the active site
- less drug absorbed
- drug metabolised faster
- more drug excreted
What is pharmacodynamic tolerance?
Less action at active site
- fewer drug receptors
- less efficient drug receptors
Describe withdrawal phenomena
The withdrawal effect of a drug is usually the reverse of the acute effect
i.e. opioid acute effect is constipation, withdrawal effect diarrhoea
Development of tolerance may lead to physical dependence in order to avoid withdrawal effects
Describe the reward pathway
Neurones project from ventral tegmental area to the nucleus accumbens and prefrontal cortex
When VTA neurones are stimulated dopamine is release
This causes a sensation of pleasure/reward
Why has the reward pathway has evolved?
Normally activated by eating, drinking and sex
Therefore encourages “healthy” behaviours that lead to propagation of your genes
How can some drugs tap int the reward pathway and increase dopamine?
Heroin increases firing rate of dopaminergic neurones
Amphetamine increases dopamine release
Cocaine inhibits dopamine intake
Alcohol
*This produces the psychological component of addiction -“craving”
What are the “good” effects of cocaine?
Stimulant and euphoriant
Increases alertness and energy
Increased confidence and impaired judgement
lessens appetite and desire for sleep
What are the “bad” effects of cocaine?
Damage to nose and airways
Convulsions with resp failure
cardiac arrythmias and MI
hypertension and CVA
toxic confusion
paranoid psychosis
What are cocaine withdrawal effects?
Depression Irritability Agitation Craving Hyperphagia Hypersomnia
What are some opiates?
Opium Morphine Heroin Methadone Codeine and dihydrocodeine
What are opiate withdrawal effects?
Craving Insomnia Yawning Muscle pain and cramps Increased salivary, nasal and lacrimal secretions Dilated pupils Piloerection
