Source / episode info
- **Episode:**166
- **Title:**Divine Intervention Episode 166 – USMLE Step 2CK Rapid Review Series 20 (Psych).
- **Published:**2019-10-09
- Source:Episode page
One-liner
This episode reviews high-yield psychopharmacology concepts, focusing on the diagnosis of Bipolar Disorder (manic/depressive episodes), the unique toxicities and management of Lithium (especially nephrogenic DIADH), and common side effects associated with SSRIs and SNRIs.
High-yield summary
- Bipolar Diagnosis: Requires at least one manic episode (or hypomanic, depending on severity) AND a depressive episode for full diagnosis; however, the presence of a clear manic episode alone can meet criteria if symptoms persist >1 week (unless social dysfunction/hospitalization is required).
- Lithium Toxicity & DIADH: Lithium causes nephrogenic diabetes insipidus by interfering with the inositol channel in the collecting duct principal cells. Treatment requires K+-sparing diuretics (Amiloride or Triamterene) and avoiding thiazides (like HCTZ) because volume depletion increases RAAS activity, worsening lithium reabsorption.
- Acute Mania Management: When a patient is acutely manic, the initial treatment involves an anti-psychotic agent, with Lithium added concurrently for long-term maintenance therapy.
- SSRI/SNRI Side Effects: SSRIs are associated with sexual dysfunction (low libido) and can be used to treat Premenstrual Dysphoric Disorder (PMDD) or premature ejaculation by exploiting this side effect. SNRIs (e.g., Venlafaxine) carry a risk of hypertension.
- MDD Criteria: Diagnosis requires 5 out of 9 CIGI-CAP symptoms for at least two weeks, with the absence of a major depressive episode preceding the onset of mania/hypomania to rule out Bipolar Disorder.
Learning objectives
- Differentiate the diagnostic criteria for Major Depressive Disorder (MDD) versus Bipolar Disorder.
- Identify the drug class and mechanism responsible for lithium's anti-suicidal properties.
- Recognize the signs, symptoms, and underlying pathophysiology of nephrogenic diabetes insipidus associated with lithium use.
- Select appropriate agents to treat lithium-induced DIADH while avoiding those that exacerbate RAAS activity (e.g., thiazides).
- Correlate common psychotropic drug side effects (e.g., SSRI sexual dysfunction, SNRI hypertension) with clinical management strategies.
Board exam buzzwords