alcohol Flashcards
describe how you calculate the absolute amount of alcohol (g alcohol/100ml)
%ABV x 0.78
how do you calculate units?
(%ABV x volume/ml)/1000
1 unit = 10mls or 8g of absolute alcohol
how many units should people drink? what is classified as binge drinking?
< 14 units/week
binge drinking = >8 units in one sitting
describe the 2 locations of absorption of alcohol
20% from stomach directly
80% from intestines
what is the speeds of onset of intoxication proportional to?
- proportional to gastric emptying
- post prandial, stomach does not empty as often as it needs to break down food
- so alcohol is not absorbed very well
describe the metabolism of alcohol
- only 90% is metabolised
- 10% breathed off
- 8% of metabolism occurs in liver
- 15% occurs in GIT
describe the liver metabolism of alcohol
- alcohol to acetaldehyde (toxic) via alcohol dehydrogenase (75%) and mixed fucntion oxidase (25%)
- MFO most significantly up regulated in chronic alcoholics
what is the difference in 1 high dose bolus of alcohol compared to same absolute amount of alcohol over 4 separate doses?
- one high dose bolus will saturate enzymatic system leads to higher intoxication
describe the GIT metabolism of alcohol
- alcohol –> acetaldehyde via alcohol dehydrogenase found in stomach
- females have less ADH than males in GIT
why are women more susceptible to alcohol?
men have more body water. more ADH = more body water
more water also allows alcohol to be more widely distributed
what happens next to acetaldehyde in liver and GIT metabolism?
acetaldehyde –> acetic acid via aldehyde dehydrogenase
polymorphisms can be found in this enzyme leads to asian flush
what is disulfiram?
inhibitor of aldehyde dehydrogenase
effective in alcohol aversion therapy as build up of acetaldehyde makes you feel sick and not want to drink
describe the general pharmacodynamicsof alcohol?
- low potency
- influences a lot of receptors as it has an uncompiicated shape
- but doesn’t fit a lot of receptors very well so not a lot of efficacy
what are the acute effects of alcohol on the CNS?
- depressant effect
- alcohol depresses system by: inc. inhibition, reducing excitation (reducing stimulation at NMDA receptors and reducing Ca influx so less NT exocytosis)
how does alcohol cause CNS euphoria?
- alcohol binds to mu-receptor to inhibit GABA release
- less inhibitory GABA means less inhibition on DA release by VTA DA neurones into NAcc
what parts of the brain does alcohol affect?
- corpus callosum
- hypothalamus (appetite, emotions, pain, temp)
- RAS (consciousness)
- Hippocampus (memory)
- cerebellum (movement and coordination)
- basal ganglia (perception of time)
what are the acute effects of alcohol on the CVS?
- cutaneous vasodilation = flushing (dec. Ca influx –> less VSM contraction, inc. prostaglandins –> vasodilators)
- inc. HR (SNS becomes dominant and HR inc, alcohol diminishes control of brain on arterial baroreceptors so heart receives less inhibitory input)
what is the endocrine effects of alcohol?
- alcohol dehydrogenase supresses VP release
- Less VP and less water reabsorption = diuresis
what are the chronic effects of alcohol on CNS?
- dementia - cortical atrophy and dec. cerebral white matter
- ataxia - cerebellar cortex degeneration
- Wernicke-Korsakoff’s syndrome - due to thiamine def as less food intake as calories from alcohol
what are the 2 parts of Wernicke-Korsakoff’s syndrome?
- Wernicke’s encephalopathy (affects 3rd ventricle and aqueduct)
- Korsakoff’s psychosis (affects dorsomedial thalamus, irreversible, impairs memory)
what are the chronic effects on the liver, regarding NAD+?
- need NAD+ for a lot of functions
- alcohol dominates the use of NAD+
- so NAD+ is not used for other functions
- leads to build up of other dangerous toxic by-products
what causes fatty liver?
lack of NAD+ means that the TAGs are deposited in liver
what causes hepatitis?
- mixed function oxidases unregulated in chronic alcoholics
- generate free radicals which generate an inflammatory response
- cytokines released e.g. IL-6, TNF-alpha
what causes cirrhosis?
- fibroblasts lay down fibrin supportive structures
- reduce regenerative capacity of liver
- dec. regeneration and active liver tissue
- inc. fibroblasts
what are the positive effects on the CVS?
- dec. mortality from coronary HD
- inc. HDLs
- inc. tPA levels –> dec. platelet aggregation levels
- polyphenols (red wine) may reduce free radicals
what are the GIT chronic effects of alcohol?
- damages gastric mucosa
- can lead to stomach cancer from acetaldehyde build up
- acetaldehyde is carcinogenic
what are the endocrine chronic effects of alcohol?
- inc. ACTH secretion –> Cushing’s ike syndrome
- dec. testosterone –> gynecomastia
what are the symptoms of a hangover? what causes them?
symptoms peak as BAC approaches 0
- nausea: irritant –> vagus –> vomiting centre of medulla
- headache: vasodilation
- fatigue: sleep deprivation
- restlessness: rebound excitation as BAC –> )
- polyuria, polydipsia (dec. VP secretion)
