Pharmacology for the AGACNP 2026-2027
Question 1: A 68-year-old patient with Parkinson's disease on carbidopa-
levodopa develops sudden onset of confusion, hallucinations, and
dyskinesias after starting a new medication for depression. Which
antidepressant is most likely responsible for this interaction?
A) Sertraline (Zoloft)
B) Bupropion (Wellbutrin)
C) Fluoxetine (Prozac)
D) Mirtazapine (Remeron)
Correct Answer: C) Fluoxetine (Prozac)
Rationale: SSRIs like fluoxetine can interact with carbidopa-levodopa,
potentially exacerbating dopaminergic side effects including confusion,
hallucinations, and dyskinesias. This interaction is related to serotonin-
dopamine balance. Bupropion has less serotonergic activity and is less likely
to cause this interaction. Sertraline also has some risk but fluoxetine has a
longer half-life and more significant drug interactions.
Question 2: A patient with refractory generalized tonic-clonic seizures is
started on valproic acid (Depakote). Which laboratory parameter requires
the most frequent monitoring?
A) Serum creatinine
B) Liver function tests (AST, ALT)
,C) Complete blood count
D) Serum sodium
Correct Answer: B) Liver function tests (AST, ALT)
Rationale: Valproic acid is associated with hepatotoxicity, which can be severe
and even fatal, especially in children and patients with mitochondrial
disorders. Liver function tests should be monitored before starting therapy
and at regular intervals. Other adverse effects include thrombocytopenia,
weight gain, and hyperammonemia. Valproic acid is teratogenic and should
be avoided in pregnancy.
Question 3: A patient on clozapine (Clozaril) for treatment-resistant
schizophrenia presents with fever, sore throat, and fatigue. What is the
priority action?
A) Administer antibiotics empirically
B) Draw a complete blood count with differential
C) Order a chest X-ray
D) Start antiviral therapy
Correct Answer: B) Draw a complete blood count with differential
Rationale: Clozapine is associated with agranulocytosis (severe neutropenia),
which can be life-threatening. Fever and sore throat are classic early signs of
agranulocytosis. A CBC with differential should be drawn immediately to
assess the absolute neutrophil count (ANC). If ANC is significantly decreased,
clozapine should be held and the patient evaluated for infection. Clozapine
requires mandatory monitoring through the REMS program.
,Question 4: A 45-year-old patient on phenytoin (Dilantin) for seizure
control is started on fluconazole for a fungal infection. What is the primary
concern?
A) Decreased phenytoin levels and breakthrough seizures
B) Increased phenytoin levels and toxicity
C) Decreased fluconazole levels
D) Increased risk of hepatotoxicity
Correct Answer: B) Increased phenytoin levels and toxicity
Rationale: Fluconazole inhibits CYP450 enzymes, including CYP2C9 and
CYP2C19, which are responsible for phenytoin metabolism. This leads to
increased phenytoin levels and risk of toxicity (ataxia, nystagmus, confusion).
Phenytoin levels should be monitored closely when starting or stopping
fluconazole. Phenytoin has nonlinear pharmacokinetics, making it
particularly susceptible to drug interactions.
Question 5: A patient is admitted with status epilepticus that has not
responded to two doses of lorazepam. Which medication should be
considered next?
A) Propofol (Diprivan)
B) Fosphenytoin (Cerebyx)
C) Ketamine (Ketalar)
D) Midazolam continuous infusion
Correct Answer: B) Fosphenytoin (Cerebyx)
Rationale: Fosphenytoin is a second-line agent for status epilepticus after
benzodiazepine failure. It is a prodrug of phenytoin that can be administered
IV or IM and has better tolerability than phenytoin (less local tissue irritation,
no propylene glycol toxicity). Propofol and midazolam infusions are reserved
, for refractory status epilepticus (third-line). Ketamine may be considered in
refractory cases but is not second-line.
Question 6: A patient on risperidone (Risperdal) develops galactorrhea and
gynecomastia. What is the mechanism causing these symptoms?
A) Serotonin receptor antagonism
B) Dopamine D2 receptor blockade in the tuberoinfundibular pathway
C) Histamine H1 receptor blockade
D) Alpha-1 adrenergic receptor blockade
Correct Answer: B) Dopamine D2 receptor blockade in the
tuberoinfundibular pathway
Rationale: Risperidone blocks dopamine D2 receptors in the
tuberoinfundibular pathway, which disinhibits prolactin secretion from the
anterior pituitary. Elevated prolactin causes galactorrhea, gynecomastia, and
sexual dysfunction. This is more common with risperidone and paliperidone
than with other atypical antipsychotics. Hyperprolactinemia is dose-
dependent and may improve with dose reduction.
Question 7: A patient with bipolar disorder is switched from lithium to
valproic acid due to lithium-induced tremor. Which statement about
valproic acid is correct?
A) Valproic acid has a narrower therapeutic index than lithium
B) Valproic acid is preferred for acute mania due to faster onset
C) Valproic acid has no teratogenic risk
D) Valproic acid does not require monitoring of serum levels