PEBC Pharmacology Basics 2 — Questions and Answers
Question 1: Which pharmacokinetic parameter describes the fraction of an administered drug that reaches systemic circulation unchanged?
- Volume of distribution
- Bioavailability (Correct answer)
- Clearance
- Half-life
Correct answer: Bioavailability
Bioavailability (F) represents the fraction of a drug dose that reaches systemic circulation in an active form after administration.
Question 2: A drug has a narrow therapeutic index. What does this mean clinically?
- The drug requires less frequent dosing
- There is a small difference between therapeutic and toxic doses (Correct answer)
- The drug is poorly absorbed orally
- The drug has a long half-life
Correct answer: There is a small difference between therapeutic and toxic doses
A narrow therapeutic index means the toxic dose is only slightly higher than the effective dose, requiring careful monitoring.
Question 3: Which receptor type directly opens an ion channel upon ligand binding?
- G protein-coupled receptor
- Nuclear receptor
- Ionotropic receptor (Correct answer)
- Tyrosine kinase receptor
Correct answer: Ionotropic receptor
Ionotropic receptors (ligand-gated ion channels) directly gate ion channels when a ligand binds, producing rapid effects.
Question 4: What is the primary site of drug metabolism in the body?
- Kidney
- Lung
- Liver (Correct answer)
- Intestine
Correct answer: Liver
The liver is the primary organ for drug metabolism, containing high concentrations of cytochrome P450 enzymes.
Question 5: A competitive antagonist shifts the agonist dose-response curve in which direction?
- Left, with no change in Emax
- Right, with no change in Emax (Correct answer)
- Right, with decreased Emax
- Left, with increased Emax
Correct answer: Right, with no change in Emax
A competitive antagonist shifts the agonist dose-response curve to the right (higher EC50) but Emax remains unchanged because it can be overcome with more agonist.
Question 6: Which phase II metabolic reaction involves conjugation of a drug with glucuronic acid?
- Oxidation
- Glucuronidation (Correct answer)
- Hydrolysis
- Reduction
Correct answer: Glucuronidation
Glucuronidation is a phase II conjugation reaction catalyzed by UDP-glucuronosyltransferases that adds glucuronic acid to drugs, increasing water solubility.
Question 7: Which term describes a drug that binds to a receptor and produces a submaximal response even at full receptor occupancy?
- Full agonist
- Partial agonist (Correct answer)
- Competitive antagonist
- Inverse agonist
Correct answer: Partial agonist
A partial agonist has intrinsic efficacy less than 1, so it cannot produce the maximum response a full agonist achieves even when all receptors are occupied.
PEBC Pharmacology Basics 2
Which pharmacokinetic parameter describes the fraction of an administered drug that reaches systemic circulation unchanged?