Master the board step 3

Master the Boards: USMLE Step 3
Basic Science Correlate
High-potency D2 receptor antagonists produce a dystonic reaction by
nigrostriatal dopamine D2 receptor blockade, which leads striatal cholinergic
output. Thus, anticholinergics are the first-line treatment.
A 35-year-old male presents with poor adherence to chlorpromazine and haloperidol.
He complains of tics and other uncontrolled movements. His wife reports
that even when he takes his medications, they don’t appear to help his paranoia.
What is the next step in management?
a. Add risperidone
b. Add diphenhydramine
c. Change to clozapine
d. Increase the dose of chlorpromazine
e. Increase the dose of haloperidol
Answer: C. The case describes 2 main problems in management, poor response to
therapy prescribed and movement disorder as a side effect from the regimen. Clozapine
is the most effective antipsychotic for schizophrenia and also has no incidence of movement
disorders. It is a second-line therapy because of the risk of seizures and agranulocytosis.
Remember to monitor CBC to watch for bone marrow suppression.
Tardive dyskinesia can be
treated with benztropine.
A 78-year-old male with a slow-growing stomach tumor in palliative care is
brought in by the family, who have noticed increased sedation and difficulty eating.
They are concerned because he continues to lose more weight. On examination,
he has repetitive movements of his lips and tongue. He has limited facial
expression. His medications include morphine, metoclopramide, and hydrochlorothiazide.
Which of the following is the most appropriate management?
a. Decrease morphine
b. Discontinue metoclopramide
c. Start omeprazole
d. Start prochlorperazine
e. Place NG tube for supplemental feedings
Answer: B. Chronic use of dopamine antagonists, including antimetics (metoclopramide,
prochlorperazine), can result in tardive dyskinesia. Management includes
discontinuing the offending drug and, if indicated, beginning a newer antipsychotic.
Anxiety Disorders
Anxiety disorders are characterized by anxiety that interferes with daytime
functioning and is not due to any other identifiable causes of symptoms. Other
conditions that may present as an anxiety disorder include the following:
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