Alcohol Flashcards
What is alcohol?
A drug
Also Organic liquids with hydroxyl group OH
What are the first 4 compounds of the alcohol class?
methanol, ethanol, propanol, butanol
What is Methanol used for?
Anti-freeze, solvents and some fuels
What effect does methanol have on the body?
TOXIC! Metabolised to formaldehyde and then formic acid - acidosis is toxic = blindness
How would you treat Methanol Toxicity?
Alcohol +/- dialysis (ethanol competitively inhibits alcohol dehydrogenase)
What is the recommended intake of alcohol (ethanol)?
14 units a week Same for both men and women Spread over at least 3 days No more than 6 units consumed in a single sitting Several rest days
Where is alcohol absorbed?
Mainly in small bowel (limited absorption in the stomach)
Where and how is alcohol initially metabolised?
alcohol dehydrogenase in stomach – only limited
What effect does a full stomach have on alcohol metabolism?
Slows gastric emptying, therefore alcohol is in the stomach longer and is more metabolized before entering small bowel
Also increases portal blood flow increasing metabolism
More metabolised in stomach prevents saturation of enzymes in liver
Which medications cause an increase in absorption of alcohol?
Antihistamines and metaclopramide etc as they increase gastric emptying
Does champagne go to your head quicker and why?
Aerated drinks are absorbed faster
What effect does drinking spirits have?
Absorption actually slower at high level and spirits irritate gastric mucosa and delay emptying
What conditions allow for quickest absorption?
concentrations of 20-30% (not too high) on an empty stomach.
- drinking sherry
Why do women have a lower tolerance for alcohol?
Alcohol is water soluble
Females have a higher subcut fat percentage. Males have more lean mass and a higher blood volume even for the same weight
Males have a bigger pool for dilution
Also – women in general have a lower level of alcohol dehydrogenase
What is the pathway for the metabolism of alcohol?
Alcohol - (alcohol dehydrogenase) - acetaldehyde - (aldehyde dehydrogenase) - acetate + CO2 + H2O
Where does the majority of the metabolism occur?
90% occurs in liver
Small volume in pancreas and brain!
Where does the excretion of alcohol occur?
All routes
5% breath
At what rate is alcohol removed from the blood?
15mg/100ml/hour. Roughly one unit an hour.
Which ethnic groups can’t handle alcohol as well, and why?
Aborigines, inuits, eskimos, Japanese
Because they lack alcohol dehydrogenase
Why do south east asians often get flushing when drinking alcohol?
Deficient or ineffective variant of aldehyde dehydrogenase
Acetaldehyde is unpleasant and toxic.
Does drinking regularly increase your tolerance?
It is possible to up regulate alcohol dehydrogenase activity
In heavy drinking analagous and alternative pathways activated including MEOS – microsomal enzyme oxidase system, Catalase and Induction of CP450
What consequences does activation of the MEOS pathway have?
Production of hydrogen ions (REDOX) which must be disposed of by
- Inhibition of hepatic gluconeogensis - munchies and hypoglycaemia
- Citric acid cycle (Krebs) inhibition = prodution of lactic acid
- Fatty acid oxidaition impairment - excess ketogenesis and lipid syntehsis = FAT
What is alcoholic ketoacidosis?
Associated with malnourished state. Excess NADH, impaired fatty acid metabolsim (increased substrate available), fasting state
In contrast to diabetic ketoacidosis – low or normal glucose with high ketones (usually beta-hydroxybutyrate). Can result in death
What effects does Alcohol have on the CNS?
CNS depressor as it increases levels of GABBA which is a neurotransmitter inhibitor
What effect does alcohol have on areas of the brain?
Cortex – disinhibtion, talkativeness, anxiolytic
Limbic system – memory loss, confusion, disorientation
Cerebellum – Loss of muscular coordination and slurred speech
Reticular formation (upper brain stem) – consciousness
Lower brain stem – control of breathing and blood pressure
Why does alcohol make you pee more?
Volume of fluid drank
Inhibits ADH - reduces water reabsorption and clearer urine
What effect does alcohol have on the heart?
Heavy heart beat - Alcohol is a negative inotrope so our hearts beat faster to maintain the same cardiac output
Why does alcohol cause a headache during hangover?
Contains certain substances - congeners and serotonin
What biochemical investigations would you do to test if someone was a chronic drinker?
Gamma GT (ethanol induces gamma GT when entering cycle)
MCV
Triglycerides (indicates alcohol excess - caused by increased synthesis in the liver)
What would you test in a comatose patient to exclude alcohol as a cause?
Glucose - diabetes?
Serum Osmolality - (normal 275-295)
If normal can calculate osmolal gap - if bigger than normal indicates something in blood
What investigations would you do in a patient with known alcohol related health disease presenting with abdominal pain?
LFTs
Amylase - would indicate pancreatitis as a cause
What differentials would you have for someone with known alcohol related health disease, presenting with abdominal pain?
Peptic ulceration +/- perforation, pancreatitis, alcoholic hepatitis, ascites +/- peritonitis
What makes up the liver function test?
ALT (alanine aminotransferase) Bilirubin “Alk phos” (alkaline phosphatase) Albumin GGT (“gamma GT” or glutamyl transpeptidase) PTR (prothrombin ratio)
What is ALT and what does it indicate?
Found especially in liver
Present in hepatocytes and released when they release their contents
Marker of liver damage rather than function
What is ALP and what does it indicate?
Found in liver, bone, small intestine, kidneys, placenta
Liver – especially bile canaliculi
Bone – osteoblasts
Kidneys – proximal tubules
Small intestine – epithelium
What is Gamma GT and what does it indicate?
Found in liver (also kidneys, pancreas, prostate)
Cell membranes of bile ducts, GB etc
Sensitive – too sensitive!
Most labs no longer offer as first-line LFT
Can reflect enzyme induction (see next slide)
What is albumin and what does it indicate?
Synthesised in liver
Half-life is ~3 weeks
Albumin falls in the systemic inflammatory response – capillary permeability associated with inflammation causes redistribution
So not terribly useful as a marker of current liver synthetic function