Source / episode info
- **Episode:**68
- **Title:**Divine Intervention Episode 68 – Psych Pharm Part 2 (Final Part)
- **Published:**2019-01-07
- Source:Episode page
One-liner
This episode provides an exhaustive review of psychopharmacology, detailing the pathophysiology of schizophrenia via dopamine pathways (mesolimbic/mesocortical), comparing typical and atypical antipsychotics based on D2/5-HT2A receptor ratios, outlining management for bipolar disorder and lithium toxicity, and reviewing various drugs of abuse.
High-yield summary
- Schizophrenia Pathophysiology: Positive symptoms are linked to excess dopamine in the mesolimbic pathway; negative symptoms are linked to low dopamine in the mesocortical pathway.
- Antipsychotic Receptor Logic: Atypical antipsychotics (e.g., clozapine, risperidone) block 5-HT2A receptors, which increases dopamine release in the mesocortical and tuberoinfundibular pathways, thereby improving negative symptoms and reducing hyperprolactinemia.
- Typical vs. Atypical: High-potency typical agents (e.g., haloperidol) are excellent for positive symptoms but carry a high risk of extrapyramidal symptoms (EPS).
- Lithium Toxicity: Lithium is nephrotoxic; toxicity can be exacerbated by any agent that increases the activity of the Renin-Angiotensin-Aldosterone System (RAAS), such as thiazide diuretics or NSAIDs. Treatment involves ADH receptor antagonists like amiloride or triamterene.
- EPS Management: Acute dystonia is treated with anticholinergics (e.g., benztropine); Akathisia with alpha-2 adrenergic blockers (e.g., propranolol); Parkinsonism with dopamine agonists (e.g., benztropine).
Learning objectives
- Differentiate the pathophysiology of positive vs. negative symptoms in schizophrenia using dopamine pathway models.
- Compare and contrast the side effect profiles and receptor mechanisms of typical versus atypical antipsychotics.
- Identify appropriate pharmacological treatments for specific extrapyramidal symptoms (EPS).
- Recognize the mechanism, risks, and management of lithium toxicity, particularly concerning RAAS activation.
- Understand the unique metabolic and behavioral effects associated with various drugs of abuse (e.g., marijuana, PCP).
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