NAPLEX QBANK Pharmacology and Mechanism of Action Questions and Answers

Question 1

A patient is being treated for gout with allopurinol. Which of the following best describes the mechanism of action responsible for its therapeutic effect?

Accepted Answer

Inhibiting xanthine oxidase, which reduces the production of uric acid

Answer

Allopurinol and its active metabolite, oxypurinol, lower uric acid levels by inhibiting xanthine oxidase. This enzyme is responsible for the conversion of hypoxanthine to xanthine and then to uric acid, the final step in purine metabolism.

Question 2

A patient with gastroesophageal reflux disease (GERD) is prescribed omeprazole. This drug provides symptom relief primarily by which of the following mechanisms?

Accepted Answer

Irreversibly inhibiting the H+/K+ ATPase pump in parietal cells

Answer

Omeprazole is a proton pump inhibitor (PPI) that specifically and irreversibly blocks the H+/K+ ATPase enzyme system (the 'proton pump') on the secretory surface of gastric parietal cells. This action inhibits the final step in gastric acid production.

Question 3

A patient on long-term anticoagulation with warfarin for atrial fibrillation needs to understand how the medication works. Which statement accurately describes warfarin's mechanism of action?

Accepted Answer

It inhibits the activation of vitamin K-dependent clotting factors

Answer

Warfarin inhibits the enzyme vitamin K epoxide reductase complex 1 (VKORC1). This action interferes with the activation of vitamin K, which is a necessary cofactor for the synthesis of clotting factors II, VII, IX, and X in the liver.

Question 4

A patient is prescribed clopidogrel after having a coronary artery stent placed. Which of the following is the primary mechanism by which clopidogrel exerts its antiplatelet effect?

Accepted Answer

Irreversible inhibition of the P2Y12 ADP receptor on platelets

Answer

Clopidogrel is a prodrug whose active metabolite irreversibly binds to the P2Y12 class of ADP receptors on the platelet surface. This binding prevents ADP from activating the platelets, thereby inhibiting platelet aggregation for the life of the platelet.

Question 5

A patient is brought to the emergency department with respiratory depression following a suspected heroin overdose. The administration of naloxone rapidly improves the patient's breathing. What is the mechanism of action of naloxone?

Accepted Answer

It is a competitive antagonist at opioid receptors

Answer

Naloxone is a competitive opioid receptor antagonist. It has a high affinity for opioid receptors, particularly the mu-receptor, and displaces opioids that are already bound, thereby reversing their effects, including respiratory depression.

NAPLEX QBANK Practice Test

NAPLEX QBANK Practice Test

NAPLEX QBANK Pharmacology and Mechanism of Action Questions and Answers