Repeated USMLE Questions Step 1- Review- 43- Pharmacology

Q- Overdose of acetaminophen most likely results in hepatic necrosis due to depletion of which one of the following substances?

A- Bilirubin

B- Glutathione

C- Glycogen

D- N-acetylcysteine

B- Glutathione- Overdose of acetaminophen leads to accumulation of its metabolite (NAPQI) which depletes glutathione results in accumulation of toxic products in the liver. N-acetylcysteine is the antidot of this toxicity.

Q- Which one of the following cyclic endoperoxides decreases both platelet aggregation and vascular tone?

A- Prostacyclin

B- Prostaglandin PGE1

C- Prostaglandin PGE2

D- Thromboxane

A- Prostacyclin- It is the only one on the list that decreases both platelet aggregation and vascular tone. Thromboxane increases both of them.

Q- Ethosuximide is the drug of choice for treatment of absence seizures. Which of the following is the mechanism of action of this medication?

A- Blocks calcium channels

B- Blocks sodium channels

C- Decreases GABA activity

D- Increases GABA activity

A- Blocks calcium channels- Ethosuximide blocks thalamic T-type calcium channels. It has some side effects such as fatigue, headache, itching and Stevens Johnson’s syndrome.

More Pharmacology MCQs

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