1. Which pharmacokinetic process is primarily affected by a drug’s lipid solubility?
A. Absorption
B. Excretion
C. Metabolism
D. Biotransformation
Answer: A
Rationale: Lipid solubility is a key factor in drug absorption because cell membranes are
composed of a lipid bilayer, allowing lipophilic drugs to cross more easily.
2. A patient has a low serum albumin level. How will this impact a highly protein-bound drug?
A. The free fraction of the drug will increase, potentially causing toxicity.
B. The free fraction of the drug will decrease.
C. The drug will be less effective.
D. The drug will be excreted faster by the kidneys.
Answer: A
Rationale: Highly protein-bound drugs compete for albumin binding sites; low albumin
means more free (active) drug is available in the bloodstream, increasing risk for toxicity.
,3. Which cytochrome P450 enzyme is responsible for metabolizing approximately 50% of all
clinically used drugs?
A. CYP2D6
B. CYP1A2
C. CYP3A4
D. CYP2C19
Answer: C
Rationale: CYP3A4 is the most prevalent enzyme in the liver and is responsible for
metabolizing the majority of medications.
4. If a drug has a half-life of 4 hours, how long will it take for the drug to reach steady state?
A. 8 hours
B. 16 to 20 hours
C. 12 hours
D. 24 to 32 hours
Answer: B
Rationale: Steady state is generally achieved after 4 to 5 half-lives. 4 hours x 4 = 16 hours;
4 hours x 5 = 20 hours.
5. What is the primary mechanism of action of an agonist?
A. It blocks the receptor site.
, B. It binds to a receptor and activates a physiological response.
C. It prevents the endogenous ligand from binding.
D. It permanently deactivates the cell membrane.
Answer: B
Rationale: An agonist mimics the action of endogenous substances by binding to and
activating receptors.
6. A drug that induces the CYP450 enzyme system will likely have what effect on a co-
administered substrate drug?
A. Increase the serum concentration of the substrate.
B. Slow down the metabolism of the substrate.
C. Have no effect on the substrate.
D. Decrease the serum concentration of the substrate.
Answer: D
Rationale: Enzyme inducers increase the rate of drug metabolism, which leads to lower
serum levels of the substrate drug.
7. Which route of administration is subject to the ‘first-pass effect’?
A. Sublingual
B. Intravenous