1
WGU D345 NURS 6438 Psychopharmacology
Comprehensive Final OA ACTUAL EXAM
2026/2027 | Objective Assessment Guide with
Verified Questions and Correct Answers | A-
Grade | Pass Guaranteed
DOMAIN 1: NEUROBIOLOGY & PHARMACOKINETICS/PHARMACODYNAMICS
(Questions 1-15)
Q1: A 34-year-old male with treatment-resistant depression is being considered for
pharmacogenomic testing. He is currently taking fluoxetine 40mg daily with minimal response
after 8 weeks. His CYP2D6 genotype testing reveals he is a poor metabolizer. Based on
pharmacogenomic principles, which medication adjustment would be MOST appropriate?
A. Increase fluoxetine to 60mg daily to overcome poor metabolism
B. Switch to paroxetine, which is less dependent on CYP2D6 metabolism
C. Switch to citalopram, which primarily uses CYP3A4 and CYP2C19 pathways
D. Add bupropion to enhance CYP2D6 enzyme activity
Correct Answer: C Rationale: Citalopram and its S-enantiomer escitalopram undergo
metabolism primarily through CYP3A4 and CYP2C19, with minimal CYP2D6 involvement.
Fluoxetine and paroxetine are both potent CYP2D6 inhibitors and substrates, making them
particularly problematic in poor metabolizers who already have reduced enzyme activity, leading
to supratherapeutic levels and increased side effects. Increasing fluoxetine (Option A) would
worsen toxicity. Paroxetine (Option B) is actually more CYP2D6-dependent than fluoxetine.
Bupropion (Option D) does not enhance CYP2D6 activity; rather, it is itself metabolized by
CYP2B6. Current CPIC guidelines recommend avoiding CYP2D6-dependent antidepressants in
poor metabolizers.
Q2: A 45-year-old female with bipolar disorder is prescribed valproic acid. She has a history of
obesity (BMI 34) and non-alcoholic fatty liver disease (NAFLD) with baseline ALT 52 U/L.
Which pharmacokinetic consideration MOST influences her risk for hepatotoxicity?
,2
A. Valproic acid undergoes extensive first-pass hepatic metabolism, increasing hepatocyte
exposure
B. Valproic acid is highly protein-bound, leading to liver protein overload
C. Valproic acid inhibits CYP3A4, causing accumulation of hepatotoxic metabolites
D. Valproic acid induces glucuronidation, overwhelming hepatic clearance capacity
Correct Answer: A Rationale: Valproic acid undergoes approximately 90% hepatic metabolism
through multiple pathways including glucuronidation, mitochondrial β-oxidation, and minor
CYP450 metabolism. The extensive first-pass effect means hepatocytes are repeatedly exposed
to the drug and its metabolites, including the potentially toxic 4-ene-VPA intermediate. In
patients with pre-existing hepatic dysfunction (NAFLD, elevated baseline ALT), this increased
hepatocellular stress significantly elevates risk for drug-induced liver injury. The boxed warning
for hepatotoxicity is most pronounced in the first 6 months. Option B is incorrect because protein
binding does not cause liver injury. Option C is incorrect as valproic acid is a broad CYP
inhibitor but not specifically hepatotoxic via this mechanism. Option D is incorrect because
while valproic acid does undergo glucuronidation, induction of this pathway does not cause
hepatotoxicity.
Q3: A 28-year-old male with schizophrenia is started on clozapine. His baseline absolute
neutrophil count (ANC) is 2,800/mm³. According to current FDA REMS protocols (2026), what
is the appropriate monitoring frequency for ANC during the first 6 months of treatment?
A. Weekly for 6 months, then every 2 weeks
B. Weekly for 6 months, then biweekly if counts remain stable
C. Weekly for 6 months, then monthly if ANC remains ≥2,000/mm³
D. Biweekly for 6 months, then monthly
Correct Answer: C Rationale: The FDA Clozapine REMS program (updated 2021 and current
through 2026) requires weekly ANC monitoring for the first 6 months of therapy. If ANC
remains ≥2,000/mm³ (or ≥1,500/mm³ for patients with benign ethnic neutropenia), monitoring
may transition to every 2 weeks for months 6-12, and then monthly thereafter. Option A is
incorrect because the transition is to every 2 weeks, not biweekly (which is synonymous). Option
B incorrectly states biweekly without specifying the 6-12 month timeframe. Option D is
incorrect because initial monitoring must be weekly, not biweekly. The ANC thresholds for
continuation are: ≥1,500/mm³ (or ≥1,000/mm³ with BEN) to continue treatment; 1,000-
1,499/mm³ requires interruption and enhanced monitoring.
Q4: A 52-year-old female presents with major depressive disorder and comorbid generalized
anxiety disorder. She has a history of QTc prolongation (baseline QTc 480ms) and is taking
,3
metoprolol for hypertension. Which antidepressant mechanism of action creates the HIGHEST
risk for further QTc prolongation in this patient?
A. Norepinephrine reuptake inhibition
B. Potent serotonin reuptake inhibition with hERG potassium channel blockade
C. Dopamine reuptake inhibition
D. Melatonin receptor agonism
Correct Answer: B Rationale: Citalopram and escitalopram, potent SSRIs, have well-
documented dose-dependent QTc prolongation effects through blockade of the hERG (human
ether-a-go-go-related gene) potassium channel, which is critical for cardiac repolarization. The
FDA has issued specific warnings limiting citalopram to 40mg/day (20mg in patients >60 years)
due to this risk. In a patient with baseline QTc 480ms (already prolonged; normal <440ms in
women), these agents are relatively contraindicated. Norepinephrine reuptake inhibition (Option
A, e.g., desipramine) carries some QTc risk but less than citalopram at therapeutic doses.
Dopamine reuptake inhibition (Option C, e.g., bupropion) has minimal cardiac effects. Melatonin
receptor agonism (Option D, agomelatine) has no known QTc effects. Alternative agents like
sertraline or mirtazapine would be safer choices.
Q5: A 38-year-old male with ADHD is prescribed methylphenidate extended-release. He has a
CYP2D6 ultra-rapid metabolizer genotype. Which pharmacokinetic outcome is MOST likely?
A. Therapeutic failure due to excessively rapid clearance of active drug
B. Increased risk of cardiovascular events due to accumulation
C. Enhanced efficacy due to conversion to more active metabolites
D. Reduced abuse potential due to faster elimination
Correct Answer: A Rationale: Methylphenidate undergoes extensive hepatic metabolism via
de-esterification to ritalinic acid, primarily through non-CYP esterases, with minor CYP2D6
involvement in secondary pathways. However, ultra-rapid metabolizers (multiple copies of
functional CYP2D6 alleles) demonstrate significantly enhanced clearance of many psychotropic
medications. For methylphenidate, this can result in subtherapeutic plasma concentrations,
shortened duration of action, and apparent treatment failure despite adequate dosing. The patient
may require dose increases, switching to agents less dependent on CYP2D6 (e.g.,
lisdexamfetamine, which is metabolized via hydrolysis in blood), or using immediate-release
formulations with more frequent dosing. Options B and C are incorrect because ultra-rapid
metabolism causes reduced, not increased, drug exposure. Option D is incorrect as abuse
potential is not significantly altered by metabolism rate.
, 4
Q6: A 44-year-old female with treatment-resistant depression is receiving augmentation with
lithium carbonate 300mg BID. Her current serum lithium level is 0.3 mEq/L, and she has shown
minimal improvement after 4 weeks. She has normal renal function (eGFR 92). Which
pharmacodynamic principle BEST explains why her lithium level may be subtherapeutic despite
standard dosing?
A. Lithium is primarily eliminated through hepatic metabolism, which is highly variable
B. Lithium follows zero-order kinetics at therapeutic doses, requiring higher doses for saturation
C. Lithium is exclusively renally eliminated with significant interindividual variation in
clearance
D. Lithium has high protein binding, requiring displacement for therapeutic activity
Correct Answer: C Rationale: Lithium is unique among psychiatric medications as it is not
metabolized hepatically but is filtered at the glomerulus and reabsorbed in the proximal tubule
(competing with sodium). It has a narrow therapeutic index (0.6-1.2 mEq/L for maintenance, 0.8-
1.2 for acute mania) and exhibits significant interindividual variability in renal clearance based
on age, renal function, sodium intake, and concomitant medications. Levels below 0.6 mEq/L are
generally subtherapeutic for augmentation in depression. The patient requires dose titration with
monitoring. Option A is incorrect because lithium has no hepatic metabolism. Option B is
incorrect because lithium follows first-order kinetics (though the renal transport system can
become saturated at toxic levels). Option D is incorrect because lithium has zero protein binding.
Q7: A 29-year-old male with schizophrenia is prescribed aripiprazole 15mg daily. He develops
akathisia within the first week of treatment. Which receptor binding profile BEST explains this
adverse effect?
A. High affinity D2 antagonism with rapid dissociation
B. Partial D2 agonism with intrinsic activity of 30%
C. Potent 5-HT2A antagonism with weak D2 binding
D. D2 inverse agonism reducing dopaminergic tone
Correct Answer: B Rationale: Aripiprazole is a D2 partial agonist with intrinsic activity of
approximately 30% at D2 receptors. In dopamine-rich areas (striatum), this partial agonism can
create a functional "hypodopaminergic" state relative to full agonism, triggering akathisia—a
subjective sense of restlessness with objective motor manifestations. This contrasts with full D2
antagonists, which cause akathisia through more profound dopamine blockade. The 30% intrinsic
activity is insufficient to fully stimulate postsynaptic D2 receptors but may disrupt normal
dopaminergic tone. Option A describes quetiapine's profile. Option C describes the mechanism of
atypical antipsychotics but doesn't explain akathisia specifically. Option D is incorrect as
aripiprazole is an agonist, not inverse agonist. Management includes dose reduction, addition of
propranolol, or switching to a different antipsychotic.
WGU D345 NURS 6438 Psychopharmacology
Comprehensive Final OA ACTUAL EXAM
2026/2027 | Objective Assessment Guide with
Verified Questions and Correct Answers | A-
Grade | Pass Guaranteed
DOMAIN 1: NEUROBIOLOGY & PHARMACOKINETICS/PHARMACODYNAMICS
(Questions 1-15)
Q1: A 34-year-old male with treatment-resistant depression is being considered for
pharmacogenomic testing. He is currently taking fluoxetine 40mg daily with minimal response
after 8 weeks. His CYP2D6 genotype testing reveals he is a poor metabolizer. Based on
pharmacogenomic principles, which medication adjustment would be MOST appropriate?
A. Increase fluoxetine to 60mg daily to overcome poor metabolism
B. Switch to paroxetine, which is less dependent on CYP2D6 metabolism
C. Switch to citalopram, which primarily uses CYP3A4 and CYP2C19 pathways
D. Add bupropion to enhance CYP2D6 enzyme activity
Correct Answer: C Rationale: Citalopram and its S-enantiomer escitalopram undergo
metabolism primarily through CYP3A4 and CYP2C19, with minimal CYP2D6 involvement.
Fluoxetine and paroxetine are both potent CYP2D6 inhibitors and substrates, making them
particularly problematic in poor metabolizers who already have reduced enzyme activity, leading
to supratherapeutic levels and increased side effects. Increasing fluoxetine (Option A) would
worsen toxicity. Paroxetine (Option B) is actually more CYP2D6-dependent than fluoxetine.
Bupropion (Option D) does not enhance CYP2D6 activity; rather, it is itself metabolized by
CYP2B6. Current CPIC guidelines recommend avoiding CYP2D6-dependent antidepressants in
poor metabolizers.
Q2: A 45-year-old female with bipolar disorder is prescribed valproic acid. She has a history of
obesity (BMI 34) and non-alcoholic fatty liver disease (NAFLD) with baseline ALT 52 U/L.
Which pharmacokinetic consideration MOST influences her risk for hepatotoxicity?
,2
A. Valproic acid undergoes extensive first-pass hepatic metabolism, increasing hepatocyte
exposure
B. Valproic acid is highly protein-bound, leading to liver protein overload
C. Valproic acid inhibits CYP3A4, causing accumulation of hepatotoxic metabolites
D. Valproic acid induces glucuronidation, overwhelming hepatic clearance capacity
Correct Answer: A Rationale: Valproic acid undergoes approximately 90% hepatic metabolism
through multiple pathways including glucuronidation, mitochondrial β-oxidation, and minor
CYP450 metabolism. The extensive first-pass effect means hepatocytes are repeatedly exposed
to the drug and its metabolites, including the potentially toxic 4-ene-VPA intermediate. In
patients with pre-existing hepatic dysfunction (NAFLD, elevated baseline ALT), this increased
hepatocellular stress significantly elevates risk for drug-induced liver injury. The boxed warning
for hepatotoxicity is most pronounced in the first 6 months. Option B is incorrect because protein
binding does not cause liver injury. Option C is incorrect as valproic acid is a broad CYP
inhibitor but not specifically hepatotoxic via this mechanism. Option D is incorrect because
while valproic acid does undergo glucuronidation, induction of this pathway does not cause
hepatotoxicity.
Q3: A 28-year-old male with schizophrenia is started on clozapine. His baseline absolute
neutrophil count (ANC) is 2,800/mm³. According to current FDA REMS protocols (2026), what
is the appropriate monitoring frequency for ANC during the first 6 months of treatment?
A. Weekly for 6 months, then every 2 weeks
B. Weekly for 6 months, then biweekly if counts remain stable
C. Weekly for 6 months, then monthly if ANC remains ≥2,000/mm³
D. Biweekly for 6 months, then monthly
Correct Answer: C Rationale: The FDA Clozapine REMS program (updated 2021 and current
through 2026) requires weekly ANC monitoring for the first 6 months of therapy. If ANC
remains ≥2,000/mm³ (or ≥1,500/mm³ for patients with benign ethnic neutropenia), monitoring
may transition to every 2 weeks for months 6-12, and then monthly thereafter. Option A is
incorrect because the transition is to every 2 weeks, not biweekly (which is synonymous). Option
B incorrectly states biweekly without specifying the 6-12 month timeframe. Option D is
incorrect because initial monitoring must be weekly, not biweekly. The ANC thresholds for
continuation are: ≥1,500/mm³ (or ≥1,000/mm³ with BEN) to continue treatment; 1,000-
1,499/mm³ requires interruption and enhanced monitoring.
Q4: A 52-year-old female presents with major depressive disorder and comorbid generalized
anxiety disorder. She has a history of QTc prolongation (baseline QTc 480ms) and is taking
,3
metoprolol for hypertension. Which antidepressant mechanism of action creates the HIGHEST
risk for further QTc prolongation in this patient?
A. Norepinephrine reuptake inhibition
B. Potent serotonin reuptake inhibition with hERG potassium channel blockade
C. Dopamine reuptake inhibition
D. Melatonin receptor agonism
Correct Answer: B Rationale: Citalopram and escitalopram, potent SSRIs, have well-
documented dose-dependent QTc prolongation effects through blockade of the hERG (human
ether-a-go-go-related gene) potassium channel, which is critical for cardiac repolarization. The
FDA has issued specific warnings limiting citalopram to 40mg/day (20mg in patients >60 years)
due to this risk. In a patient with baseline QTc 480ms (already prolonged; normal <440ms in
women), these agents are relatively contraindicated. Norepinephrine reuptake inhibition (Option
A, e.g., desipramine) carries some QTc risk but less than citalopram at therapeutic doses.
Dopamine reuptake inhibition (Option C, e.g., bupropion) has minimal cardiac effects. Melatonin
receptor agonism (Option D, agomelatine) has no known QTc effects. Alternative agents like
sertraline or mirtazapine would be safer choices.
Q5: A 38-year-old male with ADHD is prescribed methylphenidate extended-release. He has a
CYP2D6 ultra-rapid metabolizer genotype. Which pharmacokinetic outcome is MOST likely?
A. Therapeutic failure due to excessively rapid clearance of active drug
B. Increased risk of cardiovascular events due to accumulation
C. Enhanced efficacy due to conversion to more active metabolites
D. Reduced abuse potential due to faster elimination
Correct Answer: A Rationale: Methylphenidate undergoes extensive hepatic metabolism via
de-esterification to ritalinic acid, primarily through non-CYP esterases, with minor CYP2D6
involvement in secondary pathways. However, ultra-rapid metabolizers (multiple copies of
functional CYP2D6 alleles) demonstrate significantly enhanced clearance of many psychotropic
medications. For methylphenidate, this can result in subtherapeutic plasma concentrations,
shortened duration of action, and apparent treatment failure despite adequate dosing. The patient
may require dose increases, switching to agents less dependent on CYP2D6 (e.g.,
lisdexamfetamine, which is metabolized via hydrolysis in blood), or using immediate-release
formulations with more frequent dosing. Options B and C are incorrect because ultra-rapid
metabolism causes reduced, not increased, drug exposure. Option D is incorrect as abuse
potential is not significantly altered by metabolism rate.
, 4
Q6: A 44-year-old female with treatment-resistant depression is receiving augmentation with
lithium carbonate 300mg BID. Her current serum lithium level is 0.3 mEq/L, and she has shown
minimal improvement after 4 weeks. She has normal renal function (eGFR 92). Which
pharmacodynamic principle BEST explains why her lithium level may be subtherapeutic despite
standard dosing?
A. Lithium is primarily eliminated through hepatic metabolism, which is highly variable
B. Lithium follows zero-order kinetics at therapeutic doses, requiring higher doses for saturation
C. Lithium is exclusively renally eliminated with significant interindividual variation in
clearance
D. Lithium has high protein binding, requiring displacement for therapeutic activity
Correct Answer: C Rationale: Lithium is unique among psychiatric medications as it is not
metabolized hepatically but is filtered at the glomerulus and reabsorbed in the proximal tubule
(competing with sodium). It has a narrow therapeutic index (0.6-1.2 mEq/L for maintenance, 0.8-
1.2 for acute mania) and exhibits significant interindividual variability in renal clearance based
on age, renal function, sodium intake, and concomitant medications. Levels below 0.6 mEq/L are
generally subtherapeutic for augmentation in depression. The patient requires dose titration with
monitoring. Option A is incorrect because lithium has no hepatic metabolism. Option B is
incorrect because lithium follows first-order kinetics (though the renal transport system can
become saturated at toxic levels). Option D is incorrect because lithium has zero protein binding.
Q7: A 29-year-old male with schizophrenia is prescribed aripiprazole 15mg daily. He develops
akathisia within the first week of treatment. Which receptor binding profile BEST explains this
adverse effect?
A. High affinity D2 antagonism with rapid dissociation
B. Partial D2 agonism with intrinsic activity of 30%
C. Potent 5-HT2A antagonism with weak D2 binding
D. D2 inverse agonism reducing dopaminergic tone
Correct Answer: B Rationale: Aripiprazole is a D2 partial agonist with intrinsic activity of
approximately 30% at D2 receptors. In dopamine-rich areas (striatum), this partial agonism can
create a functional "hypodopaminergic" state relative to full agonism, triggering akathisia—a
subjective sense of restlessness with objective motor manifestations. This contrasts with full D2
antagonists, which cause akathisia through more profound dopamine blockade. The 30% intrinsic
activity is insufficient to fully stimulate postsynaptic D2 receptors but may disrupt normal
dopaminergic tone. Option A describes quetiapine's profile. Option C describes the mechanism of
atypical antipsychotics but doesn't explain akathisia specifically. Option D is incorrect as
aripiprazole is an agonist, not inverse agonist. Management includes dose reduction, addition of
propranolol, or switching to a different antipsychotic.
