COMLEX-USA Pharmacology 2

Question 1

Statins (HMG-CoA reductase inhibitors) lower LDL cholesterol primarily by:

Accepted Answer

Upregulating hepatic LDL receptors

Answer

By inhibiting hepatic cholesterol synthesis, statins upregulate LDL receptors on hepatocytes, increasing clearance of LDL from plasma.

Question 2

Which antiepileptic drug works by blocking sodium channels and is a first-line treatment for partial and generalized tonic-clonic seizures?

Accepted Answer

Phenytoin

Answer

Phenytoin stabilizes the inactive state of voltage-gated Na+ channels, reducing neuronal excitability and preventing seizure propagation.

Question 3

The antidote for acetaminophen overdose, N-acetylcysteine (NAC), works by:

Accepted Answer

Replenishing glutathione stores

Answer

NAC serves as a glutathione precursor, replenishing hepatic glutathione stores to detoxify the toxic NAPQI metabolite of acetaminophen.

Question 4

Which receptor does naloxone antagonize to reverse opioid overdose?

Accepted Answer

Mu (μ) receptor primarily

Answer

Naloxone is a competitive antagonist primarily at mu (μ) opioid receptors, reversing respiratory depression, sedation, and miosis of opioid overdose.

Question 5

Lithium toxicity is increased by which commonly prescribed drug class due to reduced renal clearance?

Accepted Answer

NSAIDs

Answer

NSAIDs reduce prostaglandin-mediated renal blood flow, decreasing lithium excretion and raising serum lithium levels into the toxic range.

COMLEX-USA Practice Test