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?
May 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?
- Down-regulation or internalisation of drug receptors
- Reduced signalling down stream of drug receptors
- Some other compensatory mechanism
What may the development of tolerance lead to?
Withdrawal symptoms
How can tolerance lead to withdrawal symptoms?
- Drug effect= reduced transmitter release
- Adaptive response is to increase sensitivity to transmitter
- When drug is removed the increased sensitivity remains
What is the withdrawal phenomena?
It is usually 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?
- The reward pathway is normally activated by eating, drinking and sex
- It therefore encourages those ‘healthy’ behaviours that lead to propagation of your genes
Give examples of high some drugs of abuse 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?
- Coca leaves chewed or brewed
- Cocaine hydrochloride is snorted or injected
- Cocaine freebase or crack cocaine is smoked
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
How is amphetamine consumed?
- Sniffed
- Swallowed
- injected
What are the effects of amphetamine?
- Effects similar to cocaine but longer lasting
- Toxic confusion occasionally with convulsions and death
- Amphetamine psychosis in heavy chronic use
Give examples of opiates.
- Opium
- Morphine
- Heroin (diamorphine)
- Methadone
- Codeine and dihydrocodeine
What is heroin available as?
- Diamorphine
- Diamorphine hydrochloride
How does purity of heroin vary?
Purity varies from 1%- 98% with average of 35% in US
What are other names for heroin?
- H
- Gear
- Smack
- Brown
How is heroin consumed?
- Snorted
- Smoking (chasing the dragon) (safest method)
- Injection (most dangerous method)
What are the effects of heroin?
- Analgesia
- Drowsiness and sleep
- Mood change (euphoria, intense pleasure)
- Cough reflex depression
- Respiratory depression
- Sensitisation of the labyrinth with nausea and vomiting
- Decreased sympathetic outflow (bradycardia and hypotension)
- Lowering of body temperature
- Pupillary constriction
- Constipation
What are the effects of heroin overdose?
- Respiratory arrest with a pulse
- Pinpoint pupils unreactive to light
- Snoring giving way to shallow respiration (<8 breaths/min)
- Bradycardia and hypotension
- Varying degree of reduced consciousness/coma
What are the effects of opiates?
Intense but transient feeling of pleasure
- “A rush”
- Almost orgasmic
- Physical and emotional anaesthetic
What are the first time side effects of opiates?
- Nausea/vomiting
- Headache
What are the medium term side effects of opiates?
- Phlebitis
- Anorexia
- Constipation
What are the long term side effects of opiates?
- Tolerance
- Withdrawal
- Social and health problems
What are the signs and symptoms of opiate withdrawal syndrome?
- Craving
- Insomnia
- Yawning
- Muscle pain and cramps
- Increased salivary, nasal and lacrimal secretions
- Dilated pupils
- Piloerection
What are the consequences of methadone maintenance?
- Decriminalises drug use
- Allows normalisation of lifestyle
- Reduces iv misuse
- Leakage on to the illicit market
What is ecstasy?
- 3,4-methylenedioxymethamphetamine
- Half of all ecstasy contain no MDMA
- Causes a relaxed euphoric state without hallucinations
What are the effects of ecstasy?
- Likened to mixture of LSD and amphetamine
- Euphoria followed by the feeling of calm
- Increased sociability
- Inability to distinguish between what is and isn’t desirable
- Effects after 20 minutes lasting 2-4 hours
What are the side effects of ecstasy?
- Nausea and dry mouth
- Increased blood pressure and temperature
- In clubs, users risk dehydration
- Large doses can cause anxiety and panic
- Drug induced psychosis
- Liver and brain cell damage
What is the most commonly used illicit drug?
Cannabis
What is the psychoactive agent in cannabis?
Tetrahydrocannabinol
What form of cannabis has a high THC content?
Skunk (sensimilla)
How can cannabis be presented?
- Marijuana
- Hashish (cannabis resin)
- Hash oil (produced by extracting cannabinoids from plant material with a solvent)
How is cannabis consumed?
- Eaten
- Usually smoked
How is production of cannabis evolving?
Becoming more professional
-THC content from 1% in’74 to 5% in ‘94 ; THC content of sensimilla 17%
What are the psychological effects of cannabis in low doses?
- Relaxing or stimulating
- Euphoriant
- Increases sociability and hilarity
- Increases appetite
- Changes in time per
What are the psychological effects of cannabis in higher doses?
- Anxiety
- Panic
- Persecutory ideation
- Hallucinatory activity
What are the ill effects of cannabis?
- Respiratory problems as with tobacco
- Toxic confusion
- Exacerbation of major mental illness
- ? Cannabis psychosis
Give examples of novel psychoactive substances.
- NPS
- Legal highs
What are anabolic steroids?
-Family of drugs comprising testosterone and many synthetic analogues
What are anabolic steroids legitamely prescribed for?
- Hypogonadism
- Muscular dystrophy
- Various anaemias
- Wasting in AIDs
Why are anabolic steroids used cosmetically?
- Use in sports enhancement
- To enhance appearance by increasing muscle mass and reducing body fat
Muscle hypertrophy from steroid use is particularly marked…
In the upper body in the pectoralis, deltoid, trapezius and bicpes
What are the side effects of anabolic steroids?
- Skin: acne, stretch marks, baldness
- Feminisation in males with hypogonadism and gynaecomastia (occasioning use of anti-oestrogens)
- Virilisation in women including hirsutism, deep voice, clitoral enlargement, menstrual irregularities , hair thinning
- Increased cholesterol and hypertension
- Growth deficits due to premature closure of epiphyses
- Cholestatic jaundice and liver tumours
What are the psychological side effects of anabolic steroids?
- Irritability and anger (‘roid rage’)
- Hypomania and mania
- Depression and suicidality on withdrawal
How is the psychological component of addiction (craving) produced?
Drugs can tap into the reward centre to increase dopamine levels
How can heroin be presented?
- Powder
- Tar like substance
