Week 10 - Alcohol Flashcards
what is alcohol
- isopropyl
- methanol
- ethanol
fermentation
- sugar dissolved in water
- yeasts multiply & convert sugar into ethanol & CO2
- alcohol content about 10-15%
distillation process
- fermentation -> heated -> alcohol given off in vapour -> vapour cooled
- alcohol content ~ 40-50%
measurement of alcohol
- BAL/BAC: concentration of alcohol in whole blood
- usually mg alcohol/100ml whole blood (or % of alchol in the blood
- SI units mmol/l
administration method
generally oral
can the molecules be ionized?
no therefore pH levels have no effect on absorption
absorption
- readily dissolves in water & passes into blood from stomach lining, intestines & colon
- 1st pass metabolism - alcohol dehydrogenase in stomach
what is absorption rate and blood alchol level affected by?
- stomach contents
- body fat, age
- female: decreased alcohol dehydrogenase in stomach and increased body fat
- medication
- concentration of alcohol in beverage
- usage (abstainers vs regular)
general absorption rates
- plateau ~1 hr after consumption
- peak levels: 15 minutes later
- drink type affects absorption
distribution
- alcohol dissolves in water therefore distributed entirely in body water
- crosses bbb & placental barrier
- circulates through lungs & vaporizes in air
excretion
- some alcohol is excreted through breath sweat and urine
- most metabolized in liver (~90-98%) at a rate of 1 standard drink/hr
2 step metabolisation process in the liver
- alcohol is converted to acetaldehyde by alcohol dehydrogenase
- acetaldehyde is converted into acetate; which escapes into bloodstream, some acetate then converted to acetyl-coenzyme A
acetyl-coenzyme A converted to water and CO2
excretion
- vary greatly between individuals (avg ~10-20mg/100ml/hr)
- metabolism depends on drinking experience
- eating speeds metabolism of alcohol
- excretion of methanol
Microsomal ethanol-oxidizing system (MEOS)
- also responsible for metabolism of alcohol
- increased activity with continuous drinking - heavy drinkers metabolize quicker
- metabolizes barbituates - cross-tolerance
interesting features of alcohol
- alcohol affects a variety of tissues
- need large dose to have an effect
- no drugs act as complete antagonists to all of the effects of alcohol
- alcohol does not work directly on specific receptor sites, but affects many sites of action
glutamate (excitatory NT)
- alcohol decreases functioning at NMDA receptor (blocks ion channel)
- chronic exposure causes up-regulation of NMDA & glutamate
- NDMA receptors in hippocampus, glutamate & GABA neurons in prefrontal cortex
GABAa-receptor-ionophore complex
-orthosteric & allosteric sites - alcohol increases GABA effects (decreases nueral activity) - so alcohol acts as a positive allosteric modulator
GABAb (metabotropic) receptors
- in ventral tegmental area less inhibition of DA release into nacc
- agonists decrease alcohol consumption, reinforcement, motivation & craving
- chronic alcohol exposure leads to changes in this receptor too
5-HT
alcohol stimulates serotonin receptor
alcohol also affects
- second messengers
- monoamine oxidase
- glycine
- acetylcholine
- endogenous opiod systems
effects on the body
- dialation of blood vessles - flushing (but decrease in body temp)
- increased urination
effects on sleep
- induces sleep but does not increase total sleep time (exception: chronic uses: increases insomnia)
- decreases REM(1st part of sleep at low doses, whole night at higher doses, tolerance ~3 days)
- REM rebound effects up cessation
effects of perception
- at high doses decreases absolute & difference thresholds for vision
- decreased visual acuity
- decrease peripheral vision
- decreased sensitivity to smell, taste and pain
subjective effects
- biphasic effect re time and dose - but not for everyone (feeling of euphoria)
- stimulant like effects may cause greater risk of abuse
effects on performance
- slowed reaction time
- decreased hand-eye coordination
- decreased speed and accuracy
- decreased vigilance
- decrease memory (storage and retrieval, en block blackout, grayout)
- sensitivity of organs in the inner ear responsible for balance
effects on behaviour
- disinhibition
- talkative, excitable, cheerful
- sleepy, unconsious
- nausea, vomiting
effects on driving
- impairs driving performance ~ 0.5-0.8
- reflected in crash statistics
conditioning
- reinforcing properties of alcohol are dose dependent
- decreased shock avoidance
- increased response rates that have been paired with shock
- similar effects in humans - alcohol decreases effect of aversive stimuli
discriminative properties
- easy discrimination from saline
- generalised to barbituates
- can be block by serotonin receptor blockers & opioid receptor blocker but not dopamine D2 blocker
self-administration in animals
- rats will drink in small doses, unless forced consumption
- deprived of food & water/ or paired associations
- generally, rats will self-administer sporadically, with periods of abstinence
self-administration in humans
- usually high consumption
- depends on culture, gender, age, availability
acute tolerance
occurs while still drinking - esp to the subjective feeling of intoxication
chronic tolerance
- develops v quickly within weeks for humans
- does not develop equally for all effects
metabolic tolerance
stimulation of alcohol dehydrogenase & MEOS
conditioned tolerance
- hypothermic effects
- environmental tolerance
early minor syndrome
- can occur while still drinking but usually > 8-12 hours
- agitation, tremors, muscles cramps, vomiting, nausea, sweating, dreams
- usually over after 48 hours
late major syndrome - delirium tremens
- 2 days of minor symptoms follow by disorientation, confusion, hallucinations, & seizures
- last 7-10 days
- can cause death if not managed
alcohol poisoning
- .3-.4 = unconscious
- .5 = death from respiratory failure <1-2 hours
hangovers
esp dangerous when have epilepsy, heart disease or diabeters
socio-cultural effects
- accidents
- relationships
- finances
- criminal behaviour
effects on reproduction - acute doses
- small doses we see disinhibition
- large doses decreases sexual arousal
effects on reproduction - chronic use
- loss of interest in sex
- impotence; shrinking testes
- menstrual dysfunction
- spontaneous abortion
- fetal alcohol syndrome (cognitive impairments, poor coordination, decreased birth weight, facial characteristics, malformed organs
effects on liver function
- hepatitis
- cirrhosis
- decrease immune functioning
effects on nervous system
- korsakoff’s syndrome (memory loss disorder)
- epilepsy
- dementia
- peripheral neuropathy (brain and spine damage, causing numbess)
cancer
- mouth, throat and liver
- increased risk with smoking
heart disease
alcoholic cardiomyopathy - cirrhosis of the heart
pharmacotherapies
- acamprosate (campral) - decrease glutamate activity
- naltrexone - opioid receptor antagonist
- disulfiram (antabuse) - blocks acetyldehyde dehydrogenase
