Pharmacology Illustrated Reviews 8th Edition Test Bank
– Questions & Answers
UNIT I: PHARMACOKINETICS & PHARMACODYNAMICS (Questions 1–25)
1. A 68-year-old man with a serum albumin of 2.1 g/dL (normal: 3.5–5.0 g/dL) is
prescribed phenytoin. Which pharmacokinetic parameter is most directly affected
by his hypoalbuminemia?
A. Bioavailability
B. Volume of distribution
C. Renal clearance
D. Hepatic first-pass metabolism
E. Receptor affinity
Correct Answer: B
Rationale: Phenytoin is highly protein-bound (approximately 90%). In
hypoalbuminemia, fewer binding sites are available, leading to an increased free
fraction of the drug and a larger apparent volume of distribution. This can
increase both therapeutic and toxic effects. Bioavailability refers to the fraction of
administered dose reaching systemic circulation and is not directly altered by
protein binding. Renal clearance and hepatic first-pass metabolism are not
primarily affected by albumin levels. Receptor affinity is a pharmacodynamic
property.
2. A 45-year-old woman is started on a drug with a half-life of 6 hours.
Approximately how long will it take to reach steady-state plasma concentration
with a constant-rate infusion?
A. 6 hours
B. 12 hours
C. 24 hours
D. 30 hours
E. 48 hours
, Correct Answer: C
Rationale: Steady state is typically reached after approximately 4–5 half-
lives. With a half-life of 6 hours, steady state occurs at approximately 24–30
hours. The rule of thumb is 4 half-lives = 94% of steady state, and 5 half-lives =
97% of steady state. Therefore, 24 hours (4 half-lives) is the best approximation
among the choices.
3. Which of the following statements best describes a drug that follows zero-
order elimination kinetics?
A. A constant fraction of the drug is eliminated per unit time
B. A constant amount of drug is eliminated per unit time
C. The elimination rate is proportional to plasma concentration
D. The half-life is independent of dose
E. The drug follows first-order absorption
Correct Answer: B
Rationale: Zero-order elimination means a constant amount of drug is
eliminated per unit time, regardless of plasma concentration. This occurs when
the elimination mechanisms are saturated (e.g., ethanol, phenytoin at high doses,
aspirin at high doses). In contrast, first-order kinetics eliminates a constant
fraction per unit time. Zero-order drugs have a half-life that increases with dose,
and clearance is not proportional to concentration.
4. A 32-year-old man is given 100 mg of a drug orally. The bioavailability (F) is 0.6.
What is the effective dose reaching systemic circulation?
A. 30 mg
B. 40 mg
C. 60 mg
D. 80 mg
E. 100 mg
Correct Answer: C
, Rationale: Bioavailability (F) represents the fraction of an administered
dose that reaches systemic circulation unchanged. Effective dose = Dose × F = 100
mg × 0.6 = 60 mg.
5. Which of the following is the most accurate definition of clearance (CL)?
A. The volume of plasma cleared of drug per unit time
B. The amount of drug eliminated per unit time
C. The volume of distribution multiplied by half-life
D. The rate of drug absorption from the gut
E. The fraction of drug bound to plasma proteins
Correct Answer: A
Rationale: Clearance is defined as the volume of plasma from which drug
is completely removed per unit time. It is expressed as volume/time (e.g.,
mL/min). The relationship is: CL = Rate of elimination / Plasma concentration.
Volume of distribution × half-life relates to clearance via the equation t½ = (0.693
× Vd) / CL.
6. A 55-year-old man is receiving a drug that is a weak base. In which body
compartment would this drug be most extensively distributed?
A. Gastric fluid (pH 1.5)
B. Plasma (pH 7.4)
C. Intracellular fluid (pH 7.0)
D. Urine (pH 8.0)
E. Interstitial fluid (pH 7.4)
Correct Answer: A
Rationale: Weak bases are ionized in acidic environments (like gastric
fluid, pH 1.5). Ionized drugs are poorly lipid-soluble and cannot easily cross
membranes, leading to ion trapping. This increases the apparent volume of
distribution because the drug accumulates in the acidic compartment. This
principle explains why weak bases distribute more extensively into acidic tissues.
, 7. Which of the following routes of administration bypasses the hepatic first-pass
effect?
A. Oral
B. Rectal (distal third)
C. Sublingual
D. Enteric-coated oral
E. Gastric instillation
Correct Answer: C
Rationale: Sublingual administration allows the drug to be absorbed
directly into the systemic venous circulation via the sublingual veins, bypassing
the portal circulation and hepatic first-pass metabolism. The distal third of the
rectum also partially bypasses first-pass metabolism via the middle and inferior
hemorrhoidal veins, but sublingual is the classic answer for complete bypass. Oral
and gastric routes undergo first-pass metabolism.
8. A 40-year-old woman is taking a drug that has a volume of distribution (Vd) of
40 L and a clearance (CL) of 2 L/hour. What is the approximate half-life of this
drug?
A. 7 hours
B. 14 hours
C. 20 hours
D. 28 hours
E. 40 hours
Correct Answer: B
Rationale: Half-life (t½) = (0.693 × Vd) / CL = (0.693 × 40 L) / (2 L/hour) =
27. ≈ 13.86 hours, approximately 14 hours.
9. A patient is administered a drug that inhibits cytochrome P450 3A4 (CYP3A4).
Which of the following is the most likely consequence?
– Questions & Answers
UNIT I: PHARMACOKINETICS & PHARMACODYNAMICS (Questions 1–25)
1. A 68-year-old man with a serum albumin of 2.1 g/dL (normal: 3.5–5.0 g/dL) is
prescribed phenytoin. Which pharmacokinetic parameter is most directly affected
by his hypoalbuminemia?
A. Bioavailability
B. Volume of distribution
C. Renal clearance
D. Hepatic first-pass metabolism
E. Receptor affinity
Correct Answer: B
Rationale: Phenytoin is highly protein-bound (approximately 90%). In
hypoalbuminemia, fewer binding sites are available, leading to an increased free
fraction of the drug and a larger apparent volume of distribution. This can
increase both therapeutic and toxic effects. Bioavailability refers to the fraction of
administered dose reaching systemic circulation and is not directly altered by
protein binding. Renal clearance and hepatic first-pass metabolism are not
primarily affected by albumin levels. Receptor affinity is a pharmacodynamic
property.
2. A 45-year-old woman is started on a drug with a half-life of 6 hours.
Approximately how long will it take to reach steady-state plasma concentration
with a constant-rate infusion?
A. 6 hours
B. 12 hours
C. 24 hours
D. 30 hours
E. 48 hours
, Correct Answer: C
Rationale: Steady state is typically reached after approximately 4–5 half-
lives. With a half-life of 6 hours, steady state occurs at approximately 24–30
hours. The rule of thumb is 4 half-lives = 94% of steady state, and 5 half-lives =
97% of steady state. Therefore, 24 hours (4 half-lives) is the best approximation
among the choices.
3. Which of the following statements best describes a drug that follows zero-
order elimination kinetics?
A. A constant fraction of the drug is eliminated per unit time
B. A constant amount of drug is eliminated per unit time
C. The elimination rate is proportional to plasma concentration
D. The half-life is independent of dose
E. The drug follows first-order absorption
Correct Answer: B
Rationale: Zero-order elimination means a constant amount of drug is
eliminated per unit time, regardless of plasma concentration. This occurs when
the elimination mechanisms are saturated (e.g., ethanol, phenytoin at high doses,
aspirin at high doses). In contrast, first-order kinetics eliminates a constant
fraction per unit time. Zero-order drugs have a half-life that increases with dose,
and clearance is not proportional to concentration.
4. A 32-year-old man is given 100 mg of a drug orally. The bioavailability (F) is 0.6.
What is the effective dose reaching systemic circulation?
A. 30 mg
B. 40 mg
C. 60 mg
D. 80 mg
E. 100 mg
Correct Answer: C
, Rationale: Bioavailability (F) represents the fraction of an administered
dose that reaches systemic circulation unchanged. Effective dose = Dose × F = 100
mg × 0.6 = 60 mg.
5. Which of the following is the most accurate definition of clearance (CL)?
A. The volume of plasma cleared of drug per unit time
B. The amount of drug eliminated per unit time
C. The volume of distribution multiplied by half-life
D. The rate of drug absorption from the gut
E. The fraction of drug bound to plasma proteins
Correct Answer: A
Rationale: Clearance is defined as the volume of plasma from which drug
is completely removed per unit time. It is expressed as volume/time (e.g.,
mL/min). The relationship is: CL = Rate of elimination / Plasma concentration.
Volume of distribution × half-life relates to clearance via the equation t½ = (0.693
× Vd) / CL.
6. A 55-year-old man is receiving a drug that is a weak base. In which body
compartment would this drug be most extensively distributed?
A. Gastric fluid (pH 1.5)
B. Plasma (pH 7.4)
C. Intracellular fluid (pH 7.0)
D. Urine (pH 8.0)
E. Interstitial fluid (pH 7.4)
Correct Answer: A
Rationale: Weak bases are ionized in acidic environments (like gastric
fluid, pH 1.5). Ionized drugs are poorly lipid-soluble and cannot easily cross
membranes, leading to ion trapping. This increases the apparent volume of
distribution because the drug accumulates in the acidic compartment. This
principle explains why weak bases distribute more extensively into acidic tissues.
, 7. Which of the following routes of administration bypasses the hepatic first-pass
effect?
A. Oral
B. Rectal (distal third)
C. Sublingual
D. Enteric-coated oral
E. Gastric instillation
Correct Answer: C
Rationale: Sublingual administration allows the drug to be absorbed
directly into the systemic venous circulation via the sublingual veins, bypassing
the portal circulation and hepatic first-pass metabolism. The distal third of the
rectum also partially bypasses first-pass metabolism via the middle and inferior
hemorrhoidal veins, but sublingual is the classic answer for complete bypass. Oral
and gastric routes undergo first-pass metabolism.
8. A 40-year-old woman is taking a drug that has a volume of distribution (Vd) of
40 L and a clearance (CL) of 2 L/hour. What is the approximate half-life of this
drug?
A. 7 hours
B. 14 hours
C. 20 hours
D. 28 hours
E. 40 hours
Correct Answer: B
Rationale: Half-life (t½) = (0.693 × Vd) / CL = (0.693 × 40 L) / (2 L/hour) =
27. ≈ 13.86 hours, approximately 14 hours.
9. A patient is administered a drug that inhibits cytochrome P450 3A4 (CYP3A4).
Which of the following is the most likely consequence?
