A 28-year-old woman comes to the psychiatry clinic complaining of a 4-week history of seve… — USMLE Step 2 CK

A 28-year-old woman comes to the psychiatry clinic complaining of a 4-week history of severely depressed mood, hypersomnolence, hyperphagia, and feeling that her "limbs are weighed down by lead." She has been unable to attend her job as an accountant for the past two weeks. Her medical history is notable for a psychiatric hospitalization three years ago when she was brought to the emergency department by police after staying awake for six consecutive days, spending her entire life savings on lottery tickets, and telling bystanders she was a "prophet of wealth." She was stabilized on a medication at that time but discontinued it one year ago because she disliked the required routine blood tests. She currently takes no medications and uses no illicit substances. Which of the following is the most appropriate next step in pharmacotherapy for this patient?

Initiate quetiapineAnswer
B
Initiate sertraline
C
Initiate venlafaxine
D
Initiate haloperidol
E
Initiate fluoxetine and phenelzine

Answer

Initiate quetiapine

This patient has a history of a manic episode characterized by grandiosity, decreased need for sleep, and impulsivity requiring hospitalization, which definitively establishes a diagnosis of bipolar I disorder. She was likely previously treated with lithium, given her aversion to routine blood tests. She is currently presenting with a major depressive episode. The treatment of bipolar depression differs significantly from unipolar major depressive disorder. First-line monotherapy options for bipolar depression include quetiapine, lurasidone, cariprazine, and lamotrigine (though lamotrigine requires slow titration and is not ideal for acute, severe symptoms). The correct answer recommends initiating quetiapine, which is an atypical antipsychotic with robust evidence for efficacy in acute bipolar depression.

Step-by-Step Solution

Analyze the patient's psychiatric history to establish a correct diagnosis.

The patient has a history of a severe manic episode (decreased need for sleep, grandiosity, impulsive spending requiring hospitalization) three years ago.

A single manic episode confirms the diagnosis of bipolar I disorder, regardless of current symptoms.

Evaluate the patient's current clinical presentation.

The patient is currently experiencing a major depressive episode with atypical features (hypersomnolence, hyperphagia, leaden paralysis).

Identifying the current phase of bipolar disorder dictates the appropriate pharmacological intervention.

Select the appropriate evidence-based pharmacotherapy for the current phase.

Quetiapine is selected as the optimal treatment.

First-line monotherapy options for bipolar depression include quetiapine, lurasidone, cariprazine, or the olanzapine-fluoxetine combination. Antidepressant monotherapy must be avoided.

Key Concept

Patients with bipolar I disorder presenting with a major depressive episode should be treated with mood stabilizers or atypical antipsychotics approved for bipolar depression (e.g., quetiapine, lurasidone) rather than antidepressant monotherapy to avoid precipitating a manic switch.

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