Repeated USMLE Questions Step 1 Review-153- Pharmacology

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Q- Which of the following antifungal medications inhibits ergosterol synthesis by blocking fungal cytochrome P450 enzymes?

A- Amphotericin B

B- Fluconazole

C- Flucytosine

D- Terbinafine

B- Fluconazole- Azoles inhibit fungal CYP450 enzymes, decreasing ergosterol synthesis and disrupting cell membrane integrity.

 

Q- A 29-year-old woman treated with lithium presents with tremor, polyuria, and confusion. Which laboratory finding is most likely present?

A- Hypercalcemia

B- Hypoglycemia

C- Hypokalemia

D- Hyponatremia

A- Hypercalcemia- Lithium can cause hyperparathyroidism, leading to elevated calcium levels, in addition to nephrogenic diabetes insipidus.

 

Q- A patient develops muscle weakness and respiratory failure after receiving a neuromuscular blocker during surgery. Which drug was most likely used?

A- Atracurium

B- Succinylcholine

C- Pancuronium

D- Rocuronium

B- Succinylcholine- Succinylcholine is a depolarizing neuromuscular blocker that can cause prolonged paralysis and hyperkalemia, especially in susceptible patients.

 

Q- A patient treated with erythromycin develops QT prolongation on ECG. What is the main mechanism behind this effect?

A- Beta-adrenergic blockade

B- Calcium channel inhibition

C- Potassium channel blockade

D- Sodium channel blockade

C- Potassium channel blockade- Macrolides like erythromycin block cardiac potassium channels, delaying repolarization and increasing the risk of QT prolongation and torsades de pointes
.

 

Q- A patient taking metoclopramide develops restlessness and involuntary muscle movements. This adverse effect is due to blockade of which receptor?

A- Dopamine receptors

B- Histamine receptors

C- Muscarinic receptors

D- Serotonin receptors

A- Dopamine receptors- Metoclopramide blocks D2 receptors in the CNS, which can cause extrapyramidal symptoms such as akathisia and dystonia.

 

Q- Which medication decreases gastric acid secretion by irreversibly inhibiting the H⁺/K⁺ ATPase pump?

A- Famotidine

B- Misoprostol

C- Omeprazole

D- Sucralfate

C- Omeprazole- Proton pump inhibitors irreversibly block the H⁺/K⁺ ATPase in parietal cells, producing profound and long-lasting acid suppression.

 

Q- A patient with hyperlipidemia is prescribed ezetimibe. What is the primary mechanism of action of this drug?

A- Decreased bile acid reabsorption

B- Increased lipoprotein lipase activity

C- Inhibition of cholesterol synthesis

D- Inhibition of intestinal cholesterol absorption

D- Inhibition of intestinal cholesterol absorption- Ezetimibe blocks the NPC1L1 transporter in the small intestine, reducing dietary and biliary cholesterol absorption.

 

Q- A patient receiving chemotherapy develops neutropenia. Which drug is used to stimulate neutrophil production?

A- Aminocaproic acid

B- Epoetin alfa

C- Filgrastim

D- Romiplostim

C- Filgrastim- Filgrastim is a granulocyte colony-stimulating factor (G-CSF) that increases neutrophil production and reduces infection risk in chemotherapy patients.

 

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