PEBC Pharmacology Basics 5

Question 1

Renal clearance of a drug is increased when the drug is:

Accepted Answer

Actively secreted by renal tubules

Answer

Active tubular secretion adds to glomerular filtration, substantially increasing total renal clearance beyond that predicted by filtration alone.

Question 2

The therapeutic effect of a drug that acts as an enzyme inhibitor is most directly related to:

Accepted Answer

Accumulation of the enzyme's substrate or reduction of its product

Answer

Enzyme inhibitors reduce conversion of substrate to product, so substrate accumulates and/or product decreases, which is the basis of the therapeutic effect.

Question 3

Which statement about drug half-life in first-order kinetics is TRUE?

Accepted Answer

Half-life is independent of the initial dose or concentration

Answer

In first-order kinetics, half-life is constant (t½ = 0.693/ke) and does not depend on the drug concentration or dose.

Question 4

Upregulation of receptors is most commonly associated with:

Accepted Answer

Chronic antagonist exposure

Answer

Prolonged receptor blockade by antagonists leads to receptor upregulation, increasing the number or sensitivity of receptors, which can cause rebound effects if the antagonist is abruptly stopped.

Question 5

Which phase I metabolic reaction is most commonly catalyzed by cytochrome P450 enzymes?

Accepted Answer

Oxidation

Answer

Oxidation is the predominant phase I reaction and is primarily carried out by cytochrome P450 (CYP) enzymes located mainly in the liver.

PEBC - Pharmacy Examining Board of Canada Practice Test

PEBC - Pharmacy Examining Board of Canada Practice Test

PEBC Pharmacology Basics 5