A 32-year-old woman is brought to the physician by her husband, who is concerned about her ability to care for herself. Three weeks ago, she quit her marketing job to start a clothing company. Since then, she has not slept more than 4 hours per night because she has been working on her business plans. She used a significant portion of their savings to fund business trips to Switzerland in order to buy “only the best quality fabrics in the world.” She has not showered and has eaten little during the past 3 days. She has had 2 similar episodes a few years back that required hospitalization and treatment in a psychiatry unit. She has also suffered from periods of depression. She is currently not taking any medications. She appears unkempt and agitated, pacing up and down the room. She speaks very fast without interruption about her business ideas. She has no suicidal ideation or ideas of self-harm. Toxicology screening is negative. Which of the following is the most appropriate pharmacotherapy for the management of this patient?

Clonazepam therapy for one year

Sertraline therapy for one year

A 28-year-old man is brought to the physician by his wife because she is worried about his unusual behavior. Two weeks ago, he was promoted and is now convinced that he will soon take over the firm. He has been working overtime at the office and spends most of his nights at parties. Whenever he comes home, he asks his wife to have sex with him and rarely sleeps more than 3 hours. He has a history of a similar episode and several periods of depression over the past 2 years. He currently takes no medications. He appears impatient, repeatedly jumps up from his seat, and says, "I have more important things to do." There is no evidence of suicidal ideation. Urine toxicology screening is negative. Long-term treatment with lithium is started. Which of the following endocrine parameters should be regularly monitored in this patient while he is undergoing treatment?

Serum thyroid-stimulating hormone

Complete blood count with differential

A 28-year-old woman is brought to the emergency department by her friends. She is naked except for a blanket and speaking rapidly and incoherently. Her friends say that she was found watering her garden naked and refused to put on any clothes when they tried to make her do so, saying that she has accepted how beautiful she is inside and out. Her friends say she has also purchased a new car she can not afford. They are concerned about her, as they have never seen her behave this way before. For the past week, she has not shown up at work and has been acting ‘strangely’. They say she was extremely excited and has been calling them at odd hours of the night to tell them about her future plans. Which of the following drug mechanisms will help with the long-term management this patient’s symptoms?

Inhibition of inositol monophosphatase and inositol polyphosphate 1-phosphatase

Increase the concentration of dopamine and norepinephrine at the synaptic cleft

Modulate the activity of gamma-aminobutyric acid receptors

Acts as an antagonist at the dopamine, serotonin and adrenergic receptors

Inhibit the reuptake of norepinephrine and serotonin from the presynaptic cleft

A 27-year-old man comes to the physician for a follow-up examination. Paroxetine therapy was initiated 6 weeks ago for a major depressive episode. He now feels much better and says he is delighted with his newfound energy. He gets around 8 hours of sleep nightly. His appetite has increased. Last year, he had two episodes of depressed mood, insomnia, and low energy during which he had interrupted his job training and stopped going to the gym. Now, he has been able to resume his job at a local bank. He also goes to the gym three times a week to work out and enjoys reading books again. His temperature is 36.5°C (97.7°F), pulse is 70/min, and blood pressure is 128/66 mm Hg. Physical and neurologic examinations show no abnormalities. On mental status examination, he describes his mood as "good." Which of the following is the most appropriate next step in management?

Continue paroxetine therapy for 2 years

Switch from paroxetine to venlafaxine therapy

Continue paroxetine therapy for 6 months

Switch from paroxetine to lithium therapy

Mood stabilizers mechanisms and selection for USMLE Step 2 CK: High-Yield Psychiatry Lessons

Mood Stabilizers - The Bipolar Balancing Act

Mood Stabilizer Selection by Mood Phase and Side Effects

Lithium: First-line for classic mania & maintenance. MOA: Modulates phosphoinositide signaling. Narrow therapeutic index (0.6-1.2 mEq/L); monitor thyroid, renal function.
Valproate: Effective for acute mania, mixed episodes, and rapid cycling. MOA: ↑GABA levels.
Lamotrigine: Key for bipolar depression maintenance. MOA: Blocks voltage-gated Na+ channels. ⚠️ Slow titration essential to prevent Stevens-Johnson Syndrome (SJS).
Atypical Antipsychotics (2nd Gen): Quetiapine, Lurasidone useful for acute depression.

⭐ Lithium is the only mood stabilizer demonstrated to reduce suicide risk in patients with bipolar disorder.

Lithium - The OG Mood Rock

Lithium’s effect on phosphoinositide and insulin pathways

Mechanism: Still debated. Primarily inhibits enzymes in the phosphoinositide pathway (↓IP₃, ↓DAG) and glycogen synthase kinase-3 (GSK-3).
Kinetics: Narrow therapeutic window (0.6-1.2 mEq/L). Requires regular plasma level monitoring.
Adverse Effects:
- 📌 LITHIUM: Leukocytosis, Insipidus (nephrogenic diabetes insipidus), Tremor (fine), Hypothyroidism, Increased weight, Uncoordinated, Miscellaneous (nausea, teratogenesis - Ebstein anomaly).
Monitoring: BMP (BUN/Cr), TSH, and plasma lithium levels.

⭐ Lithium is the only mood stabilizer demonstrated to decrease suicide risk in patients with bipolar disorder.

Anticonvulsants - Seizure Stoppers, Mood Mappers

Mood Stabilizers and Antiepileptics: Indications

Valproic Acid (Depakote):
- MOA: ↑ GABA action, blocks voltage-gated Na+ channels.
- Use: First-line for acute mania, mixed episodes, and maintenance.
- ⚠️ BBW: Hepatotoxicity, pancreatitis, teratogenicity (neural tube defects).
Lamotrigine (Lamictal):
- MOA: Blocks voltage-gated Na+ channels.
- Use: Bipolar depression & maintenance. Not effective for acute mania.
Carbamazepine (Tegretol):
- MOA: Na+ channel blockade.
- Use: Mania, maintenance.
- ⚠️ BBW: Agranulocytosis, SJS (screen HLA-B*1502 in Asians). Strong CYP450 autoinducer.

⭐ Lamotrigine's key risk is Stevens-Johnson Syndrome (SJS). This mandates a very slow dose titration, especially if used with valproate, which doubles lamotrigine levels.

Atypical Antipsychotics - Not Just for Psychosis

Mechanism: Primarily D2 & 5-HT2A receptor antagonists. This dual action modulates dopamine and serotonin pathways, stabilizing mood from both manic and depressive poles.
Clinical Use:
- Acute Mania: Effective as monotherapy or as adjuncts to lithium/valproate for rapid control.
- Bipolar Depression: Quetiapine, Lurasidone, and Olanzapine-Fluoxetine combination are notable options.
- Maintenance: Several are approved for long-term prophylaxis.

⭐ Lurasidone is a go-to for bipolar depression due to its efficacy and lower risk of metabolic side effects compared to olanzapine or quetiapine.

Atypical antipsychotic receptor binding profile

Selection Algorithm - The Bipolar Playbook

Initial selection hinges on the current episode type and long-term goals. For acute mania, severity guides therapy intensity. For bipolar depression, specific agents are preferred while avoiding antidepressant monotherapy. Maintenance therapy aims to prevent recurrence, typically using the agent that stabilized the acute episode.

⭐ Lithium is the only mood stabilizer proven to decrease suicide risk in patients with bipolar disorder.

High‑Yield Points - ⚡ Biggest Takeaways

Lithium is first-line for classic euphoric mania; requires TDM due to a narrow therapeutic index.

Valproate is preferred for mixed episodes and rapid cycling; it's a known teratogen.

Lamotrigine excels in bipolar depression maintenance but carries a risk of Stevens-Johnson syndrome.

Atypical antipsychotics are crucial for managing acute mania and can be used as monotherapy or adjuncts.

Carbamazepine is reserved for refractory cases due to CYP450 induction and drug interactions.

Selection hinges on illness polarity (mania vs. depression) and patient comorbidities.

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