2026/2027 | Midterm & Final Exam | Chamberlain |
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PART 1: MIDTERM EXAM (Q1-Q125)
SECTION 1: Pharmacokinetics & Pharmacodynamics (Q1-Q20)
Q1: A 68-year-old patient with cirrhosis is prescribed a drug that undergoes extensive
hepatic metabolism via CYP2D6. What pharmacokinetic change is most likely to occur
in this patient?
A. Increased first-pass metabolism leading to lower bioavailability
B. Decreased hepatic metabolism resulting in higher drug concentrations and prolonged
half-life [CORRECT]
C. Increased volume of distribution due to enhanced protein binding
D. Accelerated renal excretion compensating for hepatic impairment
Correct Answer: B
Rationale: Cirrhosis reduces hepatic blood flow and CYP450 enzyme activity, decreasing
drug metabolism. This leads to elevated plasma drug levels and prolonged half-life,
increasing toxicity risk. First-pass metabolism is decreased, not increased, and protein
binding is typically reduced in liver disease due to decreased albumin synthesis.
Q2: A patient taking warfarin (highly protein-bound at 99%) begins taking aspirin, which
also binds to albumin. What is the primary pharmacokinetic concern?
,A. Decreased absorption of warfarin from the GI tract
B. Displacement of warfarin from protein binding sites, increasing free drug
concentration and bleeding risk [CORRECT]
C. Increased renal excretion of both drugs
D. Enhanced metabolism of warfarin via CYP3A4 induction
Correct Answer: B
Rationale: Aspirin can displace warfarin from albumin binding sites, transiently
increasing the free (active) fraction of warfarin. This increases INR and bleeding risk
without changing total warfarin concentration. Displacement interactions are clinically
significant for highly protein-bound drugs with narrow therapeutic indices.
Q3: A drug has a therapeutic index of 2. What does this indicate about its safety profile?
A. The drug is extremely safe with a wide margin between effective and toxic doses
B. The drug has a narrow therapeutic window requiring close monitoring [CORRECT]
C. The drug is ineffective at standard doses
D. The drug requires hepatic activation to become therapeutic
Correct Answer: B
Rationale: The therapeutic index (TI) is the ratio of toxic dose to effective dose
(TD50/ED50). A TI of 2 indicates a narrow therapeutic window where the toxic dose is
only twice the effective dose, requiring careful monitoring to avoid toxicity. A safe drug
typically has a TI > 10.
Q4: A patient receives morphine 10 mg IV. The drug distributes rapidly into tissues and
reaches peak effect within minutes. Which pharmacokinetic parameter best describes
the apparent space into which the drug distributes?
A. Bioavailability
B. Clearance
C. Volume of distribution (Vd) [CORRECT]
D. Elimination rate constant
Correct Answer: C
,Rationale: Volume of distribution (Vd) is a theoretical volume representing the apparent
space in the body available to contain the drug. It relates the amount of drug in the body
to the plasma concentration. A large Vd indicates extensive tissue distribution.
Bioavailability refers to the fraction reaching systemic circulation; clearance is the
volume of blood cleared per unit time.
Q5: A 45-year-old patient with renal failure (CrCl 20 mL/min) is prescribed gentamicin.
Which pharmacokinetic phase is most affected?
A. Absorption
B. Distribution
C. Metabolism
D. Excretion [CORRECT]
Correct Answer: D
Rationale: Gentamicin is primarily eliminated unchanged by glomerular filtration. In renal
failure, reduced CrCl significantly prolongs elimination half-life and increases serum
concentrations, necessitating dose reduction or extended dosing intervals. Gentamicin
has minimal metabolism and adequate absorption/distribution are preserved.
Q6: A drug that binds to a receptor and produces a submaximal response even at high
concentrations is best described as:
A. A full agonist
B. A partial agonist [CORRECT]
C. A competitive antagonist
D. An inverse agonist
Correct Answer: B
Rationale: A partial agonist binds to receptors and produces a response, but the
maximal effect is less than that of a full agonist, even at saturating concentrations. This
is due to lower intrinsic activity (efficacy). Competitive antagonists block receptors
without activating them, and inverse agonists reduce baseline receptor activity.
, Q7: A patient taking phenytoin develops toxicity after starting fluconazole. Which
mechanism explains this interaction?
A. Fluconazole induces CYP2C9, increasing phenytoin metabolism
B. Fluconazole inhibits CYP2C9, decreasing phenytoin metabolism [CORRECT]
C. Fluconazole displaces phenytoin from albumin binding sites
D. Fluconazole enhances phenytoin renal excretion
Correct Answer: B
Rationale: Fluconazole is a potent inhibitor of CYP2C9 and CYP3A4. Phenytoin is
metabolized primarily by CYP2C9. Inhibition of this enzyme decreases phenytoin
clearance, elevating plasma concentrations and causing toxicity (nystagmus, ataxia,
confusion). This is a classic inhibitory drug-drug interaction.
Q8: A patient receives a drug with 90% first-pass hepatic metabolism orally. If the same
dose is given IV, what is expected?
A. The oral dose will produce higher plasma levels than IV
B. The IV dose will produce approximately 10 times higher bioavailability than oral
[CORRECT]
C. Both routes will produce identical plasma concentrations
D. The oral dose will have a longer half-life than IV
Correct Answer: B
Rationale: With 90% first-pass metabolism, only 10% of the oral dose reaches systemic
circulation (oral bioavailability = 10%). IV administration bypasses first-pass
metabolism, achieving 100% bioavailability. Therefore, the IV dose yields approximately
10-fold higher systemic exposure than an equivalent oral dose.
Q9: A drug with a half-life of 6 hours is administered every 6 hours. Approximately how
long will it take to reach steady-state concentration?
A. 6 hours
B. 12 hours
C. 24 hours
D. 30 hours [CORRECT]
Correct Answer: D