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Episode 349
DIP Episode 349 - The Clutch Psych Pharm Review (for the psych shelf, Step 2CK, and Step 3)
PharmacologyMedium4 - HighHas Q&A
Step 2Step 3COMLEXMedicineUSMLEStep 2Step 3COMLEX
Topic
Antidepressants (SSRIs, SNRIs, TCAs, MAOIs); Antipsychotics; Mood Stabilizers; Sleep Disorders; Neurodegenerative Disease Pharmacology.
Key Takeaway
Pharmacological management of psychiatric disorders requires understanding drug class mechanisms (e.g., -blockade vs. reuptake inhibition), recognizing critical toxicities (e.g., QRS widening, hyperprolactinemia), and knowing specific contraindications for patient populations (e.g., seizure risk with Bupropion).
Runtime: 50.3 min
Published: 2021-11-11
Completed audio: Yes
Completed notes: Yes
Anki made: Yes
Section: PSYCH, SPECIAL TOPICS/RISK FACTORS
Episode Notes
Source / episode info
- Episode: 349
- Title: Divine Intervention Episode 349 – The Clutch Psych Pharm Review (for the psych shelf, Step 2 CK, and Step 3).
- Published: 2021-11-11
- Source: Episode page
One-liner
This episode provides a comprehensive review of psychopharmacology, covering the mechanisms, side effects, toxicities, and clinical applications of major drug classes including SSR Is, SNR Is, TC As, MAO Is, antipsychotics (1st/2nd gen), mood stabilizers, and agents for sleep disorders.
High-yield summary
- Antidepressant Classes: SSR Is are first-line for most indications but carry risks of sexual dysfunction and SIADH. SNR Is can treat pain syndromes (diabetic neuropathy, fibromyalgia) but raise blood pressure.
- TCA Toxicity: TC As are cardiotoxic sodium channel blockers; QRS widening is the hallmark toxicity, treated with Sodium Bicarbonate. They also cause anticholinergic effects (_1 blockade).
- Antipsychotic Spectrum: First-generation agents are potent for positive symptoms but carry high EPS risk. Second-generation (atypical) agents improve negative symptom management and have a lower D2 receptor affinity.
- Critical Monitoring: Clozapine requires monitoring for agranulocytosis, while Lithium has narrow therapeutic index risks (nephrogenic DI).
- Opioid/Benzodiazepine Overdose: Naloxone reverses opioids; Flumazenil reverses benzodiazepines.
- Neurodegenerative Agents: A ChE inhibitors (Donepezil, Rivastigmine) boost acetylcholine levels for Alzheimer's disease.
Learning objectives
- Differentiate the mechanisms and clinical uses of major antidepressant classes (SSR Is, SNR Is, TC As, MAO Is).
- Recognize the specific toxicities and antidotes for common drug overdoses (opioids, benzodiazepines, TC As).
- Compare first-generation vs. second-generation antipsychotics regarding positive/negative symptom efficacy and side effect profiles.
- Understand the management principles of mood disorders, including initial treatment for acute mania and monitoring requirements for Lithium.
- Identify agents used to treat specific neurodegenerative or sleep disorders (e.g., A ChE inhibitors for AD; stimulants for Narcolepsy).
Board exam buzzwords
| Condition | Key Finding | Association | Board Exam Tip |
| Bupropion | NDRI, Weight loss | Smoking cessation, Anorexia Nervosa | Contraindicated in seizure disorders due to lowering the seizure threshold. |
| Tricyclic Antidepressants (TC As) | Wide QRS complex | Sodium channel blockade | Treat cardiotoxicity with Sodium Bicarbonate. Also cause _1 blockade (orthostatic hypotension). |
| Clozapine | Agranulocytosis, Myocarditis | Monitoring WBC count | Has a survival benefit and is the most effective antipsychotic for reducing suicide risk. |
| Lithium | Nephrogenic DI, Tremors | Narrow therapeutic index | Monitor renal function; treat tremors with -blockers. Requires careful monitoring due to narrow window. |
| Opioid Overdose | Respiratory depression, Bilateral pupils | Naloxone (Antagonist) | Differentiate from benzodiazepine overdose (which requires Flumazenil). |
Rapid review table
| Topic | Key Point | Context | Exam Relevance |
| SSR Is/SNR Is | First-line for MDD, GAD, OCD, PTSD. | Sexual dysfunction, SIADH risk. | Remember the class side effects (sexual dysfunction) and monitor electrolytes (SIADH). |
| MAO Is | Tranylcypromine, Phenelzine, Isocarboxazide | Tyramine-rich foods (cheese, wine, smoked meats) | Ingestion of tyramine can cause a life-threatening Hypertensive Crisis. |
| Antipsychotics | 1st Gen vs. 2nd Gen efficacy | Positive symptoms -> D2 blockade; Negative symptoms -> Serotonin modulation. | Second-generation agents are generally preferred first line due to better negative symptom coverage. |
| Alzheimer's Disease | Acetylcholine deficiency | Basal nucleus of Meynert damage | Treatment involves A ChE inhibitors (Donepezil, Rivastigmine). |
Board-speak -> diagnosis
| Board-speak / Vignette phrase | Diagnosis / Concept | Why it fits |
| A patient with depression and smoking history is started on a drug that helps weight loss and has no sexual side effects, but must be avoided in seizure disorders. | Bupropion (NDRI) | It's an NDRI; good for weight/smoking cessation; contraindicated due to lowering the seizure threshold. |
| A patient presents with bilateral pupils and respiratory depression after recreational use of fentanyl. | Opioid Intoxication | The classic presentation requires Naloxone, a specific opioid receptor antagonist. |
| A patient on tricyclic antidepressants (TC As) develops wide QRS complexes and arrhythmias upon overdose. | TCA Cardiotoxicity | TC As are sodium channel blockers; the widening QRS is the primary cardiotoxic finding, treated with Sodium Bicarbonate. |
| A woman with chronic depression who has difficulty sleeping and weight loss should be started on a drug that blocks _2 receptors and does not cause sexual dysfunction. | Mirtazapine | It's an _2 blocker; it is noted for its lack of sexual side effects, making it ideal for anorexic patients. |
| A patient with suspected bipolar mania presents acutely. What is the first-line drug? | Antipsychotic (e.g., Haloperidol) + Mood Stabilizer | Acute agitation requires immediate sedation/calming agent (antipsychotic) before mood stabilizers take effect. |
| A patient has a history of severe depression and needs to be switched from an SSRI to another antidepressant, but the clinician must wait for at least two weeks first. | Serotonin Syndrome Risk / Washout Period | Switching between serotonergic agents requires a washout period ( 2 weeks) due to high risk of serotonin syndrome. |
Differential diagnosis / distinguishing features
Antipsychotic Side Effects/Management
| Key Features | Distinguishing Findings | Next Step |
| Acute Dystonia | Sustained muscle contractions (e.g., neck twisting). | Benztropine or Benzodiazepines. |
| Akathisia | Inner restlessness, inability to stay still. | First-line: Beta-blockers; Second-line: Benzodiazepines. |
| Parkinsonism | Tremor, rigidity (often L-Dopa induced). | Treat with Benzos or Trihexyphenidyl/Dopamine agonists. |
Sleep Disorders
| Key Features | Distinguishing Findings | Next Step |
| Narcolepsy | Excessive daytime sleepiness; Cataplexy. | Stimulants (Methylphenidate, Dextroamphetamine) or Modafinil. |
| Restless Legs Syndrome (RLS) | Nocturnal urge to move legs. | Rule out Iron Deficiency Anemia; Treat with Dopamine agonists (Ropinirole). |
Management pearls
- Opioid Withdrawal: Use \alpha_2 agonists like Clonidine to manage hyperadrenergic symptoms.
- Acute Mania Management: Always initiate treatment with an antipsychotic agent first, followed by a mood stabilizer.
- TCA Cardiotoxicity: The immediate life-saving intervention for QRS widening is Sodium Bicarbonate administration.
- Lithium Toxicity: In severe cases of toxicity, rapid removal via Hemodialysis is necessary.
Don't miss
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Bupropion Contraindication: Never use Bupropion in patients with seizure disorders or eating disorders due to lowered seizure threshold.
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MAOI/Tyramine Interaction: The combination of MAO Is and tyramine-rich foods (cheese, cured meats, red wine) causes a potentially fatal Hypertensive Crisis.
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Antipsychotic Side Effect Hierarchy: Second-generation agents are superior to first-generation agents for treating negative symptoms (e.g., flat affect).
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TCA/SSRI Washout: When switching between these classes, observe a minimum 2-week washout period to prevent Serotonin Syndrome.
Integration & clinical reasoning
- Neurotransmitter Pathways: Understanding the mesolimbic pathway (positive symptoms) vs. mesocortical pathway (negative symptoms) helps explain why first-generation antipsychotics are better for positive symptoms, while second-generation agents offer broader coverage.
- Pharmacogenetics/Metabolism: The use of drugs like Phenelzine and Tranylcypromine highlights the importance of enzyme inhibition (MAO Is), which requires careful dietary management due to metabolic consequences.
- Endocrine Linkage: Lithium's effect on \text{E NaC} channels in the collecting duct explains its risk for Nephrogenic Diabetes Insipidus, linking psychopharmacology back to renal physiology.
OMM / COMLEX integration
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For COMLEX: know these viscerosomatics / Chapman points, but don't let OMM distract from emergent diagnosis and management.
- Standard emergency management (e.g., airway, breathing, circulation) takes priority over OMT in all overdose/crisis scenarios.
- For severe metabolic derangements (like TCA toxicity or hypertensive crisis), immediate medical stabilization and specific antidotes are paramount; OMT is adjunctive only after stability is achieved.
Concept connections / cross-references
- For detailed information on general psychiatric assessment and differential diagnosis of psychosis: Episode 102 (or similar episode covering Psych Assessment).
- For comprehensive review of neurotransmitter systems and receptor pharmacology: Episode 37 (or a dedicated Neurotransmitters episode).
High-yield association table
| Condition | Association | Mechanism | Clinical Significance |
| Bipolar Mania | Antipsychotic first line | Rapid calming effect on acute agitation. | Mood stabilizers take time to build up; immediate control is needed with an antipsychotic. |
| Lithium Toxicity | Nephrogenic DI | Inhibits {E NaC} channels in the collecting duct. | Preventative treatment involves thiazide diuretics or amiloride/triamterene. |
| TCA Overdose | QRS widening, Arrhythmias | Sodium channel blockade (Class I anti-arrhythmic effect). | Requires immediate administration of Sodium Bicarbonate to counteract cardiotoxicity. |
| Alzheimer's Disease | Donepezil, Rivastigmine | Acetylcholine Esterase Inhibition ({A ChE}) | Boosts synaptic acetylcholine levels; primary treatment for cognitive decline. |
Key terms glossary
| Term | Definition | Context | Example |
| NDRI | Norepinephrine-Dopamine Reuptake Inhibitor | Antidepressant class (Bupropion). | Used for depression and smoking cessation, but contraindicated in seizure disorders. |
| _2 Agonist | Alpha-2 adrenergic receptor agonist | Used to treat hyperadrenergic symptoms. | Clonidine is used in opioid withdrawal; Mirtazapine acts as an _2 blocker (increasing NE release). |
| A ChE Inhibitor | Acetylcholine Esterase Inhibitor | Treatment for cognitive decline/Alzheimer's disease. | Donepezil, Rivastigmine, Galantamine. |
| Hypertensive Crisis | Severe, acute elevation of blood pressure. | Caused by MAO Is interacting with tyramine-rich foods. | Eating aged cheese or cured meats after taking Phenelzine can trigger this crisis. |
Study optimization
| Topic | Study Approach | Priority | Resources |
| Antidepressants | Mechanism/Side Effect Pairing | High | Create a flow chart: SSRI -> Sexual Dysfunction; SNRI -> HTN/Pain; TCA -> QRS widening. |
| Psychosis Management | First-line vs. Second-line Agents | Medium-High | Memorize the side effect profiles (EPS, Hyperprolactinemia) and specific contraindications for each class. |
| Neurodegenerative Drugs | Defect/Treatment Pairing | High | Link the deficient neurotransmitter (A Ch) to the drug class ({A ChE} inhibitors). |
Question pattern recognition
- Pattern: Patient with depression, smoking history, and weight gain concern. -> Consider Bupropion or Mirtazapine. If sexual side effects are key, use Bupropion/Mirtazapine.
- Pattern: Acute mania presentation in a patient who is agitated. -> First step is an antipsychotic (e.g., Haloperidol) to calm the patient down before starting mood stabilizers.
- Pattern: Patient with suspected opioid overdose and respiratory depression. -> Administer Naloxone. If it were benzodiazepine, administer Flumazenil.
Test yourself
Common mistakes to avoid
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Mistake 1: Assuming all psych drugs are safe for eating disorder patients. Bupropion is contraindicated in seizure disorders due to lowering the seizure threshold.
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Mistake 2: Confusing the antidotes for overdose. Naloxone reverses opioids; Flumazenil reverses benzodiazepines.
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Mistake 3: Believing that all antipsychotics work equally well on negative symptoms. Second-generation agents are superior to first-generation agents for treating negative symptoms (e.g., flat affect).
Common traps
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Trap 1: Thinking that the drug used to treat Parkinsonism in L-Dopa induced hallucinations is a dopamine agonist. The correct next step is often Quetiapine, which acts as a mild antipsychotic/stabilizer.
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Trap 2: Assuming all antidepressants cause sexual side effects. Mirtazapine and Bupropion are noted for their lack of sexual side effects.
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Trap 3: Believing that the first drug given in acute mania is a mood stabilizer. The initial agent must be an antipsychotic to achieve rapid symptom control.