toxicology- paul Flashcards
(40 cards)
What is the primary route of excretion for volatile compounds like ethanol?
A. Urine
B. Bile
C. Breath
D. Sweat
E. Feces
C. Breath
Which of the following is NOT a factor influencing individual susceptibility to toxins?
A. Age
B. Diet
C. Genetic factors
D. Eye colour
E. Hormonal status
D. Eye colour
Which of the following best defines bioavailability?
A. The dose required to reach toxic levels in tissues
B. The fraction of a drug that is ionized in plasma
C. The amount of drug that enters the liver after absorption
D. The amount of a substance that reaches systemic circulation and is available for activity
E. The time taken for 50% of the drug to be eliminated
D. The amount of a substance that reaches systemic circulation and is available for activity
Which organ is primarily affected by paracetamol toxicity?
A. Heart
B. Lung
C. Liver
D. Brain
E. Kidney
C. Liver
What is the toxic metabolite formed from paracetamol by cytochrome P450 enzymes?
A. Acetaminophen sulphate
B. NAPQI
C. Glutathione
D. Arachidonic acid
E. PABA
B. NAPQI
Which enzyme system catalyzes the formation of NAPQI from paracetamol?
A. COX-1
B. UDP-glucuronyl transferase
C. CYP2E1
D. Sulphotransferase
E. GST
C. CYP2E1
What is the role of glutathione in paracetamol metabolism?
A. Enhances COX inhibition
B. Regenerates NAPQI
C. Conjugates and detoxifies NAPQI
D. Enhances bioavailability
E. Inhibits sulphate conjugation
C. Conjugates and detoxifies NAPQI
Which of the following best describes the action of N-acetylcysteine (NAC) in overdose?
A. Stimulates COX-3 to reverse toxicity
B. Acts as a serotonin antagonist
C. Replenishes glutathione and aids in NAPQI detoxification
D. Inhibits glucuronidation
E. Promotes renal excretion of paracetamol
C. Replenishes glutathione and aids in NAPQI detoxification
At what point after ingestion is plasma paracetamol concentration a reasonably accurate predictor of liver damage?
A. Immediately
B. Within 2 hours
C. After 4 hours
D. After 24 hours
E. Only after symptoms develop
C. After 4 hours
Which of the following reactions results in a non-toxic, excretable metabolite of paracetamol?
A. N-hydroxylation
B. Glucuronidation
C. Dehydration
D. Deamination
E. Peroxidation
B. Glucuronidation
Which of the following is an example of a Phase II reaction in paracetamol metabolism?
A. Sulphation
B. N-hydroxylation
C. CYP2E1 oxidation
D. Deamination
E. Hydroxylation
A. Sulphation
In overdose, why does paracetamol cause liver cell necrosis?
A. Accumulation of prostaglandins
B. Inhibition of glucuronidation
C. Depletion of glutathione and binding of NAPQI to cellular macromolecules
D. Excess sulfate conjugation
E. Overexpression of COX-3
C. Depletion of glutathione and binding of NAPQI to cellular macromolecules
What causes hypoglycaemia in paracetamol overdose?
A. Inhibition of insulin secretion
B. Increased uptake of glucose by muscles
C. Liver’s failure to release or produce glucose
D. Decreased glucose absorption in intestines
E. Increased renal glucose excretion
C. Liver’s failure to release or produce glucose
What is the threshold dose at 4 hours post-ingestion on the Rumack-Matthew nomogram to begin treatment?
A. 100 mg/L
B. 150 mg/L
C. 200 mg/L
D. 250 mg/L
E. 300 mg/L
C. 200 mg/L
Which of the following best describes why children under 3 are more resistant to paracetamol toxicity?
A. They lack glucuronidation
B. They have higher glutathione levels
C. CYP450 activity is low and sulphation is dominant
D. COX inhibition is stronger
E. More NAPQI is excreted in urine
C. CYP450 activity is low and sulphation is dominant
In cases of suspected carbon monoxide (CO) poisoning, which treatment is most effective in rapidly displacing CO from haemoglobin?
A. NSAIDs
B. Activated charcoal
C. 100% normobaric oxygen
D. Hyperbaric oxygen
E. NAC
D. Hyperbaric oxygen
Which physiological effect of CO leads to tissue damage?
A. Vasodilation of large arteries
B. Inhibition of GABA
C. Competitive binding to haemoglobin, impairing oxygen delivery
D. Increase in bicarbonate levels
E. Excessive serotonin production
C. Competitive binding to haemoglobin, impairing oxygen delivery
Which neurotransmitter is involved in paracetamol-induced analgesia?
A. GABA
B. Glutamate
C. Dopamine
D. Serotonin
E. Acetylcholine
D. Serotonin
What is a common sign of hepatic necrosis due to paracetamol overdose?
A. Diarrhoea
B. Bradycardia
C. Jaundice
D. Tachypnoea
E. Cyanosis
C. Jaundice
What is the effect of NAPQI on mitochondrial proteins?
A. Enhances electron transport
B. Inhibits oxidative phosphorylation
C. Activates pyruvate dehydrogenase
D. Increases ATP synthesis
E. Stimulates gluconeogenesis
B. Inhibits oxidative phosphorylation
Which enzyme is responsible for glucuronidation of paracetamol?
A. CYP3A4
B. COX-2
C. UDP-glucuronyl transferase
D. Glutathione S-transferase
E. Sulphotransferase
C. UDP-glucuronyl transferase
Which factor may increase susceptibility to paracetamol toxicity?
A. Fasting
B. Full stomach
C. Low alcohol consumption
D. High carbohydrate diet
E. CYP2E1 inhibition
A. Fasting
What symptom may occur within the first 24 hours of paracetamol overdose?
A. Coma
B. Hypothermia
C. Asymptomatic or nausea/vomiting
D. Jaundice
E. Seizures
C. Asymptomatic or nausea/vomiting
What laboratory result indicates severe hepatic damage?
A. ALT > 10 IU/L
B. INR > 1.2
C. ALT or AST >1000 IU/L
D. Bilirubin <10 μmol/L
E. Creatinine <50 μmol/L
C. ALT or AST >1000 IU/L
