PSA Drug Interactions

Question 1

What is a drug-drug interaction?

Accepted Answer

When one drug affects the activity of another when both are administered together

Answer

Drug-drug interactions occur when one medication modifies the effect of another, potentially causing increased toxicity, reduced efficacy, or unexpected adverse effects.

Question 2

What enzyme system is most commonly involved in drug metabolism interactions?

Accepted Answer

Cytochrome P450 (CYP450) enzyme system

Answer

The CYP450 system in the liver is responsible for metabolizing most drugs, and interactions involving CYP inducers or inhibitors are the most clinically significant.

Question 3

What happens when a CYP450 inhibitor is given with a substrate drug?

Accepted Answer

The substrate drug level increases because its metabolism is slowed

Answer

CYP450 inhibitors block the enzyme, reducing metabolism of the substrate drug, leading to higher blood levels and potentially increased toxicity.

Question 4

Why is warfarin particularly prone to drug interactions?

Accepted Answer

It has a narrow therapeutic index, is highly protein-bound, and is metabolized by multiple CYP enzymes

Answer

Warfarin's narrow therapeutic window means small changes in drug levels can cause serious bleeding or therapeutic failure, and many factors affect its metabolism.

Question 5

What is the interaction between ACE inhibitors and potassium-sparing diuretics?

Accepted Answer

Both increase potassium levels, risking dangerous hyperkalemia

Answer

ACE inhibitors reduce aldosterone-mediated potassium excretion, while potassium-sparing diuretics prevent potassium loss. Together they can cause dangerous hyperkalemia.

(PSA) Prescribing Safety Assessment Practice Test

(PSA) Prescribing Safety Assessment Practice Test

PSA Drug Interactions