Toxicology Flashcards
(30 cards)
Why does hepatic damage occur?
Liver glutathione store becomes deplete
Glutathione usually protects hepatic cells from oxidative damage
What condition would glutathione stored be reduced?
Anorexic
How is paracetamol metabolised?
Conjugation forming paracetamol glucuronide and sulphate
Oxidation forming NAPQI
How does the treatment with acetylcysteine relate to clinical outcome?
If given more than. 8 hours after ingestion there is.a 5.3% death from hepatic failure
Why are blood glucose levels low following paracetamol overdose?
Livers ability to breakdown glycogen is reduced
Why does paracetamol overdose result in elevated levels of toxic metabolite?
The conjugation pathway becomes saturated converting paracetamol into NAPQI
What are biochemical and haematological abnormalities seen in paracetamol poisoning?
AST, ALT, Bilirubin and amylase increase
Blood sugar, phosphate,platelets decrease
What organs does NAPQI damage?
Liver and kidneys
What is the AST/ALT value given for severe hepatic damage?
1000IU/L
Why is there a metabolic acidosis?
Massive indigestion
Hepatic failure
Shock Hypoperfusion Anerobic respiration
How is acetylcysteine administered?
IV for 21 hours
What are the antidotes to paracetamol poisoning?
Glutathione percursors
What is the most common paracetamol antidote?
Acetylcysteine
What substance does NAPQI alter the regulation of?
Calcium
Why is INR increased and platelet levels decreased in paracetamol overdose?
Hepatic failure causes reduction in anti thrombin
More thrombin causes DIC
DIC use up all platelets
When do adverse events occur in AC administration?
Immediately after the initial bolus dose
Why does phosphate decrease in paracetamol poisoning?
Livers ability to breakdown glycogen is reduced
How is NAPQI removed?
Conjugated with glutathione- forming cysteine and mercapturate conjugates
Possible adverse event associates with acetylcysteine?
Flushing
Urticaria
Puritus
Bronchospasm
Physical properties of carbon monoxide that render it difficult for humans to detect?
Non irritating, colourless, odourless gas
No physiological trigger
How is exogenous carbon monoxide formed?
Formed during incomplete combustion of carbon fuels
Where might carbon poisoning occur?
Car exhaust in garage
Older properties with unmaintained heating systems
Blocked chimneys above wood or gas fires
Presence with other toxins
How and why does Co poisoning cause tissue hypoxia?
Binds to Haemoglobin
Causes a decrease in arterial O2 content and shift of the oxyhemoglobin dissociation curve to the left
Oxygen not delivered to organs or tissues
Symptoms of carbon monoxide poisoning?
Headache
Dizziness and nausea
Vomiting
Tiredness and confusion
Stomach pain
Difficulty breathing
