A 25-year-old woman presents to her college campus clinic with the complaint of being unable to get up for her morning classes. She says that, because of this, her grades are being affected. For the past 6 weeks, she says she has been feeling depressed because her boyfriend dumped her. She finds herself very sleepy, sleeping in most mornings, eating more snacks and fast foods, and feeling drained of energy. She is comforted by her friend’s efforts to cheer her up but still feels guarded around any other boy that shows interest in her. The patient says she had similar symptoms 7 years ago for which she was prescribed several selective serotonin reuptake inhibitors (SSRIs) and a tricyclic antidepressant (TCA). However, none of the medications provided any long-term relief. She has prescribed a trial of Phenelzine to treat her symptoms. Past medical history is significant for a long-standing seizure disorder well managed with phenytoin. Which of the following statements would most likely be relevant to this patient’s new medication?

“While taking this medication, you should avoid drinking red wine.”

“This medication is known to cause anorgasmia during treatment.”

“You will have a risk for cardiotoxicity from this medication.”

“A common side effect of this medication is sedation.”

“While on this medication, you may have a decreased seizure threshold.”

A 24-year-old male comes into the psychiatric clinic complaining of consistent sadness. He endorses feelings of worthlessness, anxiety, and anhedonia for the past couple months but denies feeling suicidal. He further denies any past episodes of feeling overly energetic with racing thoughts. Confident of the diagnosis, you recommend frequent talk therapy along with a long-term prescription of a known first-line medication for this disorder. What is the drug and what are some of the most frequently encountered side effects?

Selective serotonin reuptake inhibitor; anorgasmia, insomnia

Selective serotonin reuptake inhibitor; hypomania, suicidal thoughts

Tricyclic antidepressants; hypomania, suicidal thoughts

Monoamine oxidase inhibitors; Orthostatic hypotension, weight gain

Tricyclic antidepressants; Orthostatic hypotension, anticholinergic effects

A 23-year-old woman is brought to the emergency department by her boyfriend 10 minutes after ingesting at least 15 acetaminophen tablets. She has been admitted to the hospital several times in the past few months after attempted self-harm. She claims that her boyfriend is “extremely selfish” and “does not care for her.” She says she feels lonely and wants her boyfriend to pay attention to her. Her boyfriend says that they have broken up 10 times in the past year because she is prone to outbursts of physical aggression as well as mood swings. He says that these mood swings last a few hours and can vary from states of “exuberance and affection” to states of “depression.” On examination, the patient appears well-dressed and calm. She has normal speech, thought processes, and thought content. Which of the following is the most likely diagnosis?

Narcissistic personality disorder

A 34-year-old female presents to a counselor at the urging of her parents because they are concerned that she might be depressed. After recently breaking up with her long-term boyfriend, she moved back in with her parents because she could not handle making decisions alone. Soon after their breakup, she started going on 5–7 dates a week. She has been unemployed for 3 years, as her boyfriend took care of all the bills. In the past year, she thought of looking for a job but never felt confident enough to start the process. Her mom arranges her doctor's appointments and handles her car maintenance. She describes feeling uneasy when she is alone. She has hypothyroidism treated with levothyroxine. She does not smoke or drink alcohol. Vital signs are normal. Mental status exam shows a neutral affect. Neurologic examination shows no focal findings. Which of the following is the most likely diagnosis?

Histrionic personality disorder

Pharmacotherapy role in personality disorders for USMLE Step 3: High-Yield Psychiatry Lessons

Pharmacotherapy Principles - Pills for Problems

Core Principle: Pharmacotherapy is adjunctive to psychotherapy, not curative. It targets specific, severe symptoms rather than the entire disorder.
Strategy: Match the pill to the problem domain. Avoid polypharmacy whenever possible.

⭐ Borderline Personality Disorder (BPD) is the most studied for pharmacotherapy, yet no medication is FDA-approved specifically for it. Treatment focuses on symptom domains like mood lability (SSRIs, mood stabilizers) and impulsivity.

Symptom-Domain Targeting - The Med Matrix

Pharmacotherapy targets symptom clusters, not the entire disorder. It's an adjunct to psychotherapy.

Symptom Domain	First-Line Meds	Second-Line Meds	Target Disorders
Affective Dysregulation (mood lability, rejection sensitivity)	* SSRIs (Fluoxetine) * Mood Stabilizers (Valproate, Lamotrigine)	* Second-Generation Antipsychotics (SGAs)	BPD
Impulsive-Behavioral (aggression, self-injury)	* SSRIs * Mood Stabilizers (Valproate)	* SGAs * Naltrexone	BPD, ASPD
Cognitive-Perceptual (suspiciousness, transient psychosis)	* Low-dose SGAs (Risperidone, Olanzapine)	* Low-dose First-Generation Antipsychotics (FGAs)	BPD, STPD

Cluster-Specific Pearls - A, B, C, easy as 1-2-3

Pharmacotherapy targets symptoms, not the disorder itself. Tailor agents to the predominant cluster features.

Cluster A (Odd/Eccentric):
- - Schizotypal: Use low-dose antipsychotics (e.g., risperidone, olanzapine) for managing psychotic-like symptoms, such as magical thinking and perceptual distortions.
Cluster B (Dramatic/Emotional):
- - Borderline/Antisocial: Target impulsivity and affective dysregulation.
  - - Mood stabilizers (lamotrigine, valproate) are first-line for emotional lability.
  - - SSRIs can help with impulsivity and anger.
- - ⚠️ Avoid Benzodiazepines: High risk of paradoxical disinhibition and worsening impulsivity.
Cluster C (Anxious/Fearful):
- - Avoidant: Focus on anxiety and social phobia.
  - - SSRIs (e.g., escitalopram) or SNRIs for rejection sensitivity and anxiety.

⭐ For Borderline Personality Disorder, Dialectical Behavior Therapy (DBT) is the cornerstone of treatment; pharmacotherapy is adjunctive for specific symptoms like mood instability or impulsivity.

High‑Yield Points - ⚡ Biggest Takeaways

Pharmacotherapy is adjunctive to psychotherapy, targeting symptoms rather than the core disorder.

Focus on treating symptom clusters: affective dysregulation, impulsivity, or cognitive-perceptual symptoms.

SSRIs are often used for depressive and anxiety symptoms.

Low-dose antipsychotics can manage transient psychosis, anger, and impulsivity.

Mood stabilizers (e.g., valproate, lamotrigine) can help with affective lability and impulsivity.

⚠️ Avoid benzodiazepines due to risks of disinhibition, dependence, and abuse.

There are no FDA-approved medications specifically for any personality disorder.

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