WGU D398 Introduction to Pharmacology Objective Assessment (OA)
2026/2027 | Western Governors University | 60 Verified Questions with
Detailed Rationales
Section 1: Pharmacokinetics (Questions 1-15)
Question 1
What is the process by which a drug moves from its site of administration into the bloodstream?
A) Distribution
B) Metabolism
C) Absorption
D) Excretion
Correct Answer: C
Rationale: Absorption is the process by which a drug moves from its site of administration into
the bloodstream. This is the first phase of pharmacokinetics . Distribution involves transport to
tissues; metabolism is the breakdown of drugs; excretion is elimination of drugs.
Question 2
The transfer of a drug from the bloodstream to the site of action is known as:
A) Absorption
B) Distribution
C) Metabolism
D) Excretion
Correct Answer: B
Rationale: Distribution is the transport of a drug from the bloodstream to the site of action (e.g.,
tissues, organs) . The rate and extent of distribution depend on blood flow, protein binding, and
the drug's ability to cross membranes.
Question 3
The chemical alteration of a drug by the body is called:
A) Absorption
B) Distribution
C) Metabolism (biotransformation)
D) Excretion
Correct Answer: C
,Rationale: Metabolism (biotransformation) is the chemical alteration of a drug by the body,
primarily in the liver. The goal is to convert lipid-soluble drugs into more water-soluble forms for
easier excretion .
Question 4
The removal of a drug from the body is called:
A) Absorption
B) Distribution
C) Metabolism
D) Excretion (elimination)
Correct Answer: D
Rationale: Excretion (elimination) is the process by which drugs and their metabolites are
removed from the body . The kidneys are the primary organs for excretion, but drugs can also
be excreted through the lungs, bile, sweat, and breast milk.
Question 5
What is the half-life of a drug?
A) The time it takes for the drug to be absorbed
B) The time it takes for the drug to be excreted
C) The time required for the plasma concentration of a drug to decrease by 50%
D) The time required for the drug to reach peak concentration
Correct Answer: C
Rationale: Half-life (t½) is the time required for the plasma concentration of a drug to decrease
by 50%. It is a key pharmacokinetic parameter that determines dosing frequency and time to
reach steady state (approximately 4-5 half-lives).
Question 6
Drugs that are highly protein-bound are:
A) Easily excreted in urine
B) More likely to have drug-drug interactions
C) Less likely to have drug-drug interactions
D) More rapidly metabolized
Correct Answer: B
Rationale: Highly protein-bound drugs compete for binding sites on plasma proteins. If a patient
is on two highly protein-bound drugs, one may displace the other, increasing the free
concentration and risk of toxicity .
Question 7
The cytochrome P450 (CYP450) enzyme system is primarily involved in:
A) Drug absorption
B) Drug metabolism
, C) Drug distribution
D) Drug excretion
Correct Answer: B
Rationale: The cytochrome P450 enzyme system (located in the liver) is primarily responsible
for Phase I drug metabolism . It oxidizes drugs to make them more water-soluble.
Question 8
What is the first-pass effect?
A) The immediate absorption of a drug after intravenous administration
B) The metabolism of an orally administered drug by the liver before it reaches systemic
circulation
C) The excretion of a drug by the kidneys
D) The distribution of a drug to the tissues
Correct Answer: B
Rationale: The first-pass effect refers to the metabolism of an orally administered drug by the
liver before it reaches systemic circulation. This reduces the bioavailability of the drug .
Question 9
What is bioavailability?
A) The amount of drug that is absorbed and reaches systemic circulation
B) The time it takes for a drug to be absorbed
C) The volume of distribution of a drug
D) The rate of drug metabolism
Correct Answer: A
Rationale: Bioavailability is the fraction of an administered dose of a drug that reaches the
systemic circulation . The bioavailability of an intravenous drug is 100%; oral drugs have lower
bioavailability due to first-pass metabolism.
Question 10
What is the therapeutic index of a drug?
A) The ratio of the dose required to produce a therapeutic effect to the dose that produces
toxicity
B) The time required for the drug to reach peak concentration
C) The volume of distribution of the drug
D) The drug's half-life
Correct Answer: A
Rationale: The therapeutic index (TI) is the ratio of the dose required to produce a therapeutic
effect to the dose that produces toxicity (LD50/ED50). A narrow therapeutic index indicates that
the drug has a small margin of safety and requires therapeutic drug monitoring .
2026/2027 | Western Governors University | 60 Verified Questions with
Detailed Rationales
Section 1: Pharmacokinetics (Questions 1-15)
Question 1
What is the process by which a drug moves from its site of administration into the bloodstream?
A) Distribution
B) Metabolism
C) Absorption
D) Excretion
Correct Answer: C
Rationale: Absorption is the process by which a drug moves from its site of administration into
the bloodstream. This is the first phase of pharmacokinetics . Distribution involves transport to
tissues; metabolism is the breakdown of drugs; excretion is elimination of drugs.
Question 2
The transfer of a drug from the bloodstream to the site of action is known as:
A) Absorption
B) Distribution
C) Metabolism
D) Excretion
Correct Answer: B
Rationale: Distribution is the transport of a drug from the bloodstream to the site of action (e.g.,
tissues, organs) . The rate and extent of distribution depend on blood flow, protein binding, and
the drug's ability to cross membranes.
Question 3
The chemical alteration of a drug by the body is called:
A) Absorption
B) Distribution
C) Metabolism (biotransformation)
D) Excretion
Correct Answer: C
,Rationale: Metabolism (biotransformation) is the chemical alteration of a drug by the body,
primarily in the liver. The goal is to convert lipid-soluble drugs into more water-soluble forms for
easier excretion .
Question 4
The removal of a drug from the body is called:
A) Absorption
B) Distribution
C) Metabolism
D) Excretion (elimination)
Correct Answer: D
Rationale: Excretion (elimination) is the process by which drugs and their metabolites are
removed from the body . The kidneys are the primary organs for excretion, but drugs can also
be excreted through the lungs, bile, sweat, and breast milk.
Question 5
What is the half-life of a drug?
A) The time it takes for the drug to be absorbed
B) The time it takes for the drug to be excreted
C) The time required for the plasma concentration of a drug to decrease by 50%
D) The time required for the drug to reach peak concentration
Correct Answer: C
Rationale: Half-life (t½) is the time required for the plasma concentration of a drug to decrease
by 50%. It is a key pharmacokinetic parameter that determines dosing frequency and time to
reach steady state (approximately 4-5 half-lives).
Question 6
Drugs that are highly protein-bound are:
A) Easily excreted in urine
B) More likely to have drug-drug interactions
C) Less likely to have drug-drug interactions
D) More rapidly metabolized
Correct Answer: B
Rationale: Highly protein-bound drugs compete for binding sites on plasma proteins. If a patient
is on two highly protein-bound drugs, one may displace the other, increasing the free
concentration and risk of toxicity .
Question 7
The cytochrome P450 (CYP450) enzyme system is primarily involved in:
A) Drug absorption
B) Drug metabolism
, C) Drug distribution
D) Drug excretion
Correct Answer: B
Rationale: The cytochrome P450 enzyme system (located in the liver) is primarily responsible
for Phase I drug metabolism . It oxidizes drugs to make them more water-soluble.
Question 8
What is the first-pass effect?
A) The immediate absorption of a drug after intravenous administration
B) The metabolism of an orally administered drug by the liver before it reaches systemic
circulation
C) The excretion of a drug by the kidneys
D) The distribution of a drug to the tissues
Correct Answer: B
Rationale: The first-pass effect refers to the metabolism of an orally administered drug by the
liver before it reaches systemic circulation. This reduces the bioavailability of the drug .
Question 9
What is bioavailability?
A) The amount of drug that is absorbed and reaches systemic circulation
B) The time it takes for a drug to be absorbed
C) The volume of distribution of a drug
D) The rate of drug metabolism
Correct Answer: A
Rationale: Bioavailability is the fraction of an administered dose of a drug that reaches the
systemic circulation . The bioavailability of an intravenous drug is 100%; oral drugs have lower
bioavailability due to first-pass metabolism.
Question 10
What is the therapeutic index of a drug?
A) The ratio of the dose required to produce a therapeutic effect to the dose that produces
toxicity
B) The time required for the drug to reach peak concentration
C) The volume of distribution of the drug
D) The drug's half-life
Correct Answer: A
Rationale: The therapeutic index (TI) is the ratio of the dose required to produce a therapeutic
effect to the dose that produces toxicity (LD50/ED50). A narrow therapeutic index indicates that
the drug has a small margin of safety and requires therapeutic drug monitoring .
