NR 546 Week 2 Exam V2 | NR 546 Advanced
Pharmacology Psychopharmacology for the
PMHNP | Actual Q&A with Rationale (NR546 Week
2 Exam) | Chamberlain University
1. When a medication acts as a partial agonist at a neurotransmitter receptor, how does it
behave in the presence of an excess of the natural neurotransmitter?
A. It acts as a net antagonist by competing for binding sites.
B. It increases the total signal intensity beyond that of the natural ligand.
C. It has no effect on the natural ligand’s binding.
D. It permanently deactivates the receptor site.
Correct Answer: A
Explanation: Partial agonists have lower intrinsic activity than full agonists. When a full
agonist is present in high concentrations, the partial agonist competes for the same
receptors, effectively lowering the overall signal transduction. This ‘stabilizing’ effect is a
core principle in using drugs like aripiprazole for mood regulation and psychosis.
2. Which cytochrome P450 enzyme is most frequently involved in the metabolism of
approximately 50% of all clinically used medications?
A. CYP2D6
B. CYP3A4
C. CYP1A2
,D. CYP2C19
Correct Answer: B
Explanation: CYP3A4 is the most abundant isoform in the human liver and is responsible
for metabolizing the largest portion of prescribed drugs. Inhibition of this enzyme can lead
to toxic levels of drugs like benzodiazepines or statins. Understanding its activity is crucial
for preventing dangerous drug-drug interactions in psychiatric practice.
3. A patient is started on fluoxetine (Prozac), a known potent inhibitor of CYP2D6. Which of
the following drugs would reach toxic levels if co-administered?
A. A drug that is a CYP2D6 inducer
B. A drug that bypasses liver metabolism
C. A drug that is an agonist for CYP1A2
D. A drug that is a CYP2D6 substrate
Correct Answer: D
Explanation: Fluoxetine inhibits the CYP2D6 enzyme, preventing it from breaking down
substrates that rely on this pathway. If a substrate drug is administered simultaneously, its
plasma concentration will rise, increasing the risk of toxicity. PMHNPs must monitor
patients closely when adding fluoxetine to a regimen containing drugs like tricyclic
antidepressants or beta-blockers.
4. In signal transduction, what is the role of the ‘third messenger’?
A. A neurotransmitter binding to the extracellular receptor
, B. An intracellular enzyme such as a protein kinase
C. The G-protein coupled to the receptor
D. A gene transcription factor that moves to the nucleus
Correct Answer: B
Explanation: Signal transduction involves a cascade of messengers that relay a signal from
the cell surface to the nucleus. The third messenger is typically a protein kinase that
phosphorylates other proteins within the cell. This process eventually leads to the
activation of fourth messengers, which regulate gene expression and long-term
neuroplasticity.
5. Which mechanism describes how an ‘inverse agonist’ affects a receptor that has
constitutive activity?
A. It reduces the receptor’s activity below the baseline level.
B. It blocks the receptor but maintains the baseline activity.
C. It mimics the natural ligand’s effect perfectly.
D. It increases the receptor’s activity without binding to the active site.
Correct Answer: A
Explanation: Some receptors exhibit constitutive activity, meaning they produce a
baseline signal even without a ligand. An inverse agonist binds to these receptors and shuts
down this baseline activity, bringing it below the resting level. This is distinct from a
Pharmacology Psychopharmacology for the
PMHNP | Actual Q&A with Rationale (NR546 Week
2 Exam) | Chamberlain University
1. When a medication acts as a partial agonist at a neurotransmitter receptor, how does it
behave in the presence of an excess of the natural neurotransmitter?
A. It acts as a net antagonist by competing for binding sites.
B. It increases the total signal intensity beyond that of the natural ligand.
C. It has no effect on the natural ligand’s binding.
D. It permanently deactivates the receptor site.
Correct Answer: A
Explanation: Partial agonists have lower intrinsic activity than full agonists. When a full
agonist is present in high concentrations, the partial agonist competes for the same
receptors, effectively lowering the overall signal transduction. This ‘stabilizing’ effect is a
core principle in using drugs like aripiprazole for mood regulation and psychosis.
2. Which cytochrome P450 enzyme is most frequently involved in the metabolism of
approximately 50% of all clinically used medications?
A. CYP2D6
B. CYP3A4
C. CYP1A2
,D. CYP2C19
Correct Answer: B
Explanation: CYP3A4 is the most abundant isoform in the human liver and is responsible
for metabolizing the largest portion of prescribed drugs. Inhibition of this enzyme can lead
to toxic levels of drugs like benzodiazepines or statins. Understanding its activity is crucial
for preventing dangerous drug-drug interactions in psychiatric practice.
3. A patient is started on fluoxetine (Prozac), a known potent inhibitor of CYP2D6. Which of
the following drugs would reach toxic levels if co-administered?
A. A drug that is a CYP2D6 inducer
B. A drug that bypasses liver metabolism
C. A drug that is an agonist for CYP1A2
D. A drug that is a CYP2D6 substrate
Correct Answer: D
Explanation: Fluoxetine inhibits the CYP2D6 enzyme, preventing it from breaking down
substrates that rely on this pathway. If a substrate drug is administered simultaneously, its
plasma concentration will rise, increasing the risk of toxicity. PMHNPs must monitor
patients closely when adding fluoxetine to a regimen containing drugs like tricyclic
antidepressants or beta-blockers.
4. In signal transduction, what is the role of the ‘third messenger’?
A. A neurotransmitter binding to the extracellular receptor
, B. An intracellular enzyme such as a protein kinase
C. The G-protein coupled to the receptor
D. A gene transcription factor that moves to the nucleus
Correct Answer: B
Explanation: Signal transduction involves a cascade of messengers that relay a signal from
the cell surface to the nucleus. The third messenger is typically a protein kinase that
phosphorylates other proteins within the cell. This process eventually leads to the
activation of fourth messengers, which regulate gene expression and long-term
neuroplasticity.
5. Which mechanism describes how an ‘inverse agonist’ affects a receptor that has
constitutive activity?
A. It reduces the receptor’s activity below the baseline level.
B. It blocks the receptor but maintains the baseline activity.
C. It mimics the natural ligand’s effect perfectly.
D. It increases the receptor’s activity without binding to the active site.
Correct Answer: A
Explanation: Some receptors exhibit constitutive activity, meaning they produce a
baseline signal even without a ligand. An inverse agonist binds to these receptors and shuts
down this baseline activity, bringing it below the resting level. This is distinct from a
