Addiction Flashcards
What are the two proposed mechanisms for dependence?
Tolerance (physiological dependence) Reward centre (basis of craving)
Define tolerance
Reduced responsiveness to a drug caused by previous admission
I.e. the drug is becoming less effective which each use
Give examples of drugs which show tolerance
Opoids, benzodiazepines, ethanol, barbiturates
What is tolerance an example of?
A homeostatic mechanism
What are the two kinds of tolerance? Give examples of each
Dispositional tolerance = less drug reaches active site
E.g. less absorption, faster metabolism, increased excretion
Pharmacodynamic tolerance = drug has less effect at active site
E.g. fewer receptors (e.g. due to downregulation/internalisation), less efficient receptors (e.g. due to reduced signalling downstream)
Why does tolerance lead to dependence?
Body adjusts to the drug as by the mechanisms mentioned, such that the drug has a lesser effect
These changes mean that when the drug is stopped, symptoms are experienced which are the opposite of the effects of the drug (withdrawal symptoms)
Give examples of the normal effect and withdrawal effect of:
Opioids
Barbiturates
Cocaine
Opioids - constipation normally, WE = diarrhoea
Barbiturates - anticonvulsants, WE = consulsions
Cocaine - elevated mood, WE = depressed mood
Describe the anatomy of the reward centre
VTA neurons project to the nucleus accumbens and release dopamine there
Nucleus accumbens linked to prefrontal cortex and release of dopamine –> sense of pleasure/reward
What normally activates the reward centre?
Sex, food, drinking
How do the following drugs interact with the reward centre: Heroine Amphetamine Cocaine Alcohol?
Heroine - increased dopaminergic neuron firing
Amphetamine - increases dopamine release
Cocaine - inhibits uptake of dopamine
Alcohol - works via inhibitory neurons
What is the prison sentence for possession/dealing of class A drugs?
10 years
What is the prison sentence for possession/dealing of class B drugs?
5 years
What is the prison sentence for possession/dealing of class C drugs?
3 years
What is a huge factor making heroine so dangerous?
Associated with criminality, poor mental health and family life
What is a huge factor making cocaine so dangerous?
It is so expensive –> financial problems and social fall out
What are two stimulants?
Cocaine
Amphetamine
What is crack cocaine?
Purified cocaine
You can smoke this
What ways can you take cocaine?
Snorting, smoking, injecting
How fast acting is cocaine? How long does its effects last?
Fast acting, short acting
What are the effects of cocaine?
Euphoria Increased alertness Impaired judgement Increased energy Increased confidence Lessens appetite and need for sleep
What are the negative effects of cocaine?
Damages nose and airway (vasoconstrictor) Cardiac arrhythmias and MI Convulsions and respiratory failure HTN and CVA Toxic confusion Paranoid psychosis
What are the withdrawal effects of cocaine?
Opposites of effects Hypersomnia Hyperphagia Depressed mood Irritability and agitation Craving
How is amphetamine generally taken?
Amphetamine sulphate
Sniffed, snorted or injected
What are the effects of amphetamine?
Similar to cocaine but longer lasting
Give examples of opiates
Opium Morphine Diamorphine (heroine) Methadone Codeine and dihydrocodeine
How do opiates work?
Act on opiate receptor to reduce pain and stimulate reward centre
What are the different ways of taking heroine?
Sniffing, smoking, injecting
People tend to resort to injecting when their tolerance increases
What are the effects of heroine?
Analgesia Drowsiness, sleep Euphoria Respiratory depression Cough reflex suppression Sensitisation of labyrinth (--> N/V) Bradycardia/hypotension Lowering body temp Pupillary constriction Constipation
What is respiratory arrest with pulse almost pathognmonic of?
Opiate OD
What tends to happen on first use of opiates?
NV and headache
What are short term consequences of opiate use?
Phlebitis
Anorexia
Constipation
What are long term consequences of opiate use?
Tolerance
Withdrawal
Social and health problems
What are the symptoms of opiate withdrawal?
Craving Insomnia Muscle pain and cramps Increased salivation, nasal and lacrimal secretions Dilated pupils Yawning Piloerection
Why is methadone good to use in heroine addicts?
Decriminalises drug use
Stops IV use and reduces problems assoc. with that
Normalises life
What is the biggest problem with ecstasy/MDMA?
Over half of ecstasy tablets don’t contain any MDMA
What are the effects of MDMA?
Euphoria
Increased sociability
Inability to distinguish between real and fake
What are the side effects of ecstasy use?
Nausea
Dry mouth
Increased BP and temp
Dehydration in clubs
What can larger doses of MDMA cause?
Anxiety, panic, psychosis
What can long term use of MDMA cause?
Chronic anxiety and depression and insomnia
What are the two active compounds in cannabis and what do they do?
THC - psychoactive substance
CBD - antipsychotic and anti-anxiety
What are the effects of cannabis?
Relaxing or stimulating Increased sociability increased hilarity Synaesthesia Changes in time perception Increased appetite
In higher doses what can cannabis cause?
Anxiety and panic, persecutory ideation, hallucinations
What are anabolic steroids illegally used for?
Building muscle and reducing fat
Especially builds pectorialis, trapezius, biceps and deltoids
What are the side effects of steroid use?
Acne, hair thinning, stretch marks Feminisation/virulization HTN, hypercholesterolaemia Growth deficits (as premature fusion of epiphyseal plates Liver tumours, cholestatic jaundice Irritability/anger (roid rage) Mania/hypomania Suicidal ideation/depression on withdrawal
