NAPLEX QBANK Pharmacology and Drug Mechanisms 3

Question 1

Statins lower cholesterol by inhibiting which enzyme?

Accepted Answer

HMG-CoA reductase

Answer

Statins competitively inhibit HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis.

Question 2

Which opioid is also an NMDA receptor antagonist, useful in neuropathic pain?

Accepted Answer

Methadone

Answer

Methadone provides mu-opioid agonism plus NMDA antagonism.

Question 3

The primary mechanism of proton pump inhibitors is:

Accepted Answer

Irreversible inhibition of gastric H+/K+ ATPase

Answer

PPIs irreversibly block the parietal cell H+/K+ ATPase proton pump.

Question 4

Which drug class can cause hyperkalemia due to aldosterone antagonism?

Accepted Answer

Potassium-sparing diuretics

Answer

Spironolactone and similar agents block aldosterone, retaining potassium.

Question 5

Phenytoin exhibits which pharmacokinetic property at therapeutic doses?

Accepted Answer

Zero-order (nonlinear) elimination

Answer

Phenytoin shows saturable metabolism, so small dose changes cause large level swings.

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