A 32-year-old woman is evaluated in the outpatient clinic for a 1-month history of severe … — USMLE Step 2 CK

A 32-year-old woman is evaluated in the outpatient clinic for a 1-month history of severe depressed mood, hypersomnia, profound fatigue, and passive suicidal ideation. She has no formal psychiatric history. However, upon further questioning, the patient's husband reports that during her college years, she had a distinct 3-week period where she slept only $3$ hours per night, spoke so rapidly she was difficult to understand, claimed she was "chosen by God to solve world hunger," and drained her savings account. Her medical history is significant for essential hypertension and obesity. Current medications include hydrochlorothiazide and a multivitamin. Her BMI is $34 \text{ kg/m}^2$ . Vital signs are temperature $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure $128/82 \text{ mm Hg}$ , and heart rate $78\text{/min}$ . Physical examination is unremarkable. Recent fasting laboratory results show a blood glucose of $124 \text{ mg/dL}$ and hemoglobin A1c of $6.2\%$ . Mental status examination reveals psychomotor retardation, blunted affect, and a depressed mood. Which of the following is the most appropriate pharmacotherapy for this patient's current episode?

A
Escitalopram
B
Haloperidol
C
Lithium carbonate
LurasidoneAnswer
E
Quetiapine

Answer

Lurasidone is the most appropriate pharmacotherapy for this patient's acute bipolar depression, given her metabolic comorbidities and concurrent use of hydrochlorothiazide.

The most appropriate pharmacotherapy is an atypical antipsychotic approved for bipolar depression that minimizes harm given the patient's comorbidities. Lurasidone fits this profile perfectly as it is highly effective for bipolar depression and is metabolically neutral, making it safe for her prediabetes and obesity. Furthermore, it avoids the severe drug-drug interaction present between lithium and her blood pressure medication (hydrochlorothiazide).

Step-by-Step Solution

Diagnose the underlying psychiatric condition based on the patient's history.

The patient has Bipolar I Disorder.

The patient is currently in a major depressive episode but has a history of a distinct 3-week period of grandiosity, decreased need for sleep, pressured speech, and reckless behavior, which meets the full criteria for a manic episode (requires >1 week).

Identify the current clinical phase requiring treatment.

Acute bipolar depression.

The patient presents with a 1-month history of severe depressed mood, hypersomnia, and suicidal ideation.

Rule out contraindicated medication classes.

Exclude antidepressant monotherapy (Escitalopram).

Antidepressant monotherapy in Bipolar I Disorder carries a significant risk of inducing a manic switch or rapid cycling.

Evaluate first-line options for bipolar depression against the patient's current medication list.

Exclude Lithium carbonate.

The patient is taking hydrochlorothiazide. Thiazide diuretics significantly decrease the renal clearance of lithium, creating a high risk for life-threatening lithium toxicity.

Evaluate the remaining options against the patient's medical comorbidities.

Exclude Quetiapine in favor of Lurasidone.

The patient has obesity (BMI

34 \text{ kg/m}^2

) and prediabetes (HbA1c

6.2\%

). Quetiapine has high metabolic liability, whereas lurasidone is metabolically neutral and FDA-approved for bipolar depression.

Key Concept

Management of acute bipolar depression requires avoiding antidepressant monotherapy to prevent manic switch, and selecting mood stabilizers or atypical antipsychotics based on patient-specific comorbidities and drug interactions (e.g., avoiding lithium with thiazides, avoiding quetiapine in metabolic syndrome).

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