, Question 1
A patient with treatment-resistant schizophrenia has not responded to adequate
trials of two different second-generation antipsychotics. Which pharmacologic
strategy is most supported by current evidence?
A. Switch to a high-potency first-generation antipsychotic at a moderate
dose.
B. Augment with clozapine after appropriate monitoring is established.
C. Add a mood stabilizer such as lamotrigine to the current antipsychotic.
D. Initiate a long-acting injectable antipsychotic despite oral
nonadherence.
Correct Answer: B - Augment with clozapine after appropriate
monitoring is established.
RATIONALE
Clozapine is the only antipsychotic with established superiority in
treatment-resistant schizophrenia and is indicated after failure of two
adequate antipsychotic trials. The other options either lack evidence
for this specific indication or do not address the definition of treatment
resistance.
Question 2
Which cytochrome P450 enzyme is primarily responsible for the metabolism
of aripiprazole, and what is the clinical implication when a strong inhibitor is
co-administered?
A. CYP3A4; aripiprazole dose should be reduced by 50%.
B. CYP2D6; aripiprazole dose should be reduced by 50%.
C. CYP1A2; aripiprazole dose should be increased.
D. CYP2C19; no dose adjustment is necessary.
Correct Answer: B - CYP2D6; aripiprazole dose should be
reduced by 50%.
Page 2
, RATIONALE
Aripiprazole is metabolized primarily by CYP2D6 and CYP3A4;
strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) can double
aripiprazole levels, necessitating a 50% dose reduction. CYP3A4
inhibitors also require dose reduction but the primary enzyme for the
interaction described is CYP2D6.
Question 3
A patient on lithium carbonate presents with coarse tremor, ataxia, and
confusion. Serum lithium level is 2.1 mEq/L. Which intervention is the
immediate priority?
A. Administer a benzodiazepine for tremor and continue lithium at a
lower dose.
B. Initiate hemodialysis and hold lithium.
C. Give intravenous fluids and monitor lithium level in 24 hours.
D. Prescribe propranolol for tremor and reassess in one week.
Correct Answer: B - Initiate hemodialysis and hold lithium.
RATIONALE
Lithium levels >2.0 mEq/L with neurologic symptoms constitute
severe toxicity requiring hemodialysis. Supportive care alone is
insufficient, and continuing lithium or using symptom management
without removing the drug can worsen outcomes.
Question 4
Which statement best describes the mechanism of action of ketamine in
treatment-resistant depression?
A. It selectively inhibits serotonin reuptake, increasing synaptic
serotonin.
B. It antagonizes NMDA receptors, promoting rapid synaptic plasticity.
C. It blocks dopamine D2 receptors, reducing psychotic symptoms.
D. It inhibits monoamine oxidase, increasing norepinephrine.
Page 3
A patient with treatment-resistant schizophrenia has not responded to adequate
trials of two different second-generation antipsychotics. Which pharmacologic
strategy is most supported by current evidence?
A. Switch to a high-potency first-generation antipsychotic at a moderate
dose.
B. Augment with clozapine after appropriate monitoring is established.
C. Add a mood stabilizer such as lamotrigine to the current antipsychotic.
D. Initiate a long-acting injectable antipsychotic despite oral
nonadherence.
Correct Answer: B - Augment with clozapine after appropriate
monitoring is established.
RATIONALE
Clozapine is the only antipsychotic with established superiority in
treatment-resistant schizophrenia and is indicated after failure of two
adequate antipsychotic trials. The other options either lack evidence
for this specific indication or do not address the definition of treatment
resistance.
Question 2
Which cytochrome P450 enzyme is primarily responsible for the metabolism
of aripiprazole, and what is the clinical implication when a strong inhibitor is
co-administered?
A. CYP3A4; aripiprazole dose should be reduced by 50%.
B. CYP2D6; aripiprazole dose should be reduced by 50%.
C. CYP1A2; aripiprazole dose should be increased.
D. CYP2C19; no dose adjustment is necessary.
Correct Answer: B - CYP2D6; aripiprazole dose should be
reduced by 50%.
Page 2
, RATIONALE
Aripiprazole is metabolized primarily by CYP2D6 and CYP3A4;
strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) can double
aripiprazole levels, necessitating a 50% dose reduction. CYP3A4
inhibitors also require dose reduction but the primary enzyme for the
interaction described is CYP2D6.
Question 3
A patient on lithium carbonate presents with coarse tremor, ataxia, and
confusion. Serum lithium level is 2.1 mEq/L. Which intervention is the
immediate priority?
A. Administer a benzodiazepine for tremor and continue lithium at a
lower dose.
B. Initiate hemodialysis and hold lithium.
C. Give intravenous fluids and monitor lithium level in 24 hours.
D. Prescribe propranolol for tremor and reassess in one week.
Correct Answer: B - Initiate hemodialysis and hold lithium.
RATIONALE
Lithium levels >2.0 mEq/L with neurologic symptoms constitute
severe toxicity requiring hemodialysis. Supportive care alone is
insufficient, and continuing lithium or using symptom management
without removing the drug can worsen outcomes.
Question 4
Which statement best describes the mechanism of action of ketamine in
treatment-resistant depression?
A. It selectively inhibits serotonin reuptake, increasing synaptic
serotonin.
B. It antagonizes NMDA receptors, promoting rapid synaptic plasticity.
C. It blocks dopamine D2 receptors, reducing psychotic symptoms.
D. It inhibits monoamine oxidase, increasing norepinephrine.
Page 3
