CETP Drug Interactions 1

Question 1

Which enzyme system is primarily responsible for metabolizing the majority of drugs, making it the most common site of pharmacokinetic drug-drug interactions?

Accepted Answer

Cytochrome P450 (CYP) system

Answer

The cytochrome P450 enzyme system in the liver metabolizes approximately 70-80% of all drugs, making it the most frequent source of clinically significant drug-drug interactions.

Question 2

A patient stabilized on warfarin begins taking fluconazole for a fungal infection. What is the most likely pharmacokinetic outcome?

Accepted Answer

Increased warfarin levels due to CYP2C9 inhibition

Answer

Fluconazole is a potent CYP2C9 inhibitor; since warfarin is primarily metabolized by CYP2C9, co-administration leads to elevated warfarin plasma levels and increased bleeding risk.

Question 3

Grapefruit juice inhibits which intestinal enzyme, thereby increasing the bioavailability of certain calcium channel blockers and statins?

Accepted Answer

CYP3A4

Answer

Grapefruit juice irreversibly inhibits intestinal CYP3A4, reducing first-pass metabolism of drugs such as felodipine, simvastatin, and lovastatin, leading to elevated plasma concentrations.

Question 4

Which drug-drug interaction mechanism is occurring when two highly protein-bound drugs compete for albumin binding sites, potentially increasing the free fraction of one drug?

Accepted Answer

Protein-binding displacement

Answer

Protein-binding displacement occurs when a drug with higher albumin affinity displaces a previously bound drug, transiently increasing its free (active) concentration.

Question 5

The concurrent use of an SSRI and a monoamine oxidase inhibitor (MAOI) can cause which potentially fatal adverse reaction?

Accepted Answer

Serotonin syndrome

Answer

Combining SSRIs with MAOIs causes excessive serotonergic stimulation, leading to serotonin syndrome characterized by hyperthermia, neuromuscular abnormalities, and autonomic instability.

CETP - Canadian Entry To Practice Practice Test

CETP - Canadian Entry To Practice Practice Test

CETP Drug Interactions 1