Match each antidepressant with its most distinctive clinical feature:

!MATCH[["Mirtazapine","Most sedating, increases appetite"],["Bupropion","No sexual dysfunction, used for smoking cessation"],["Duloxetine","FDA approved for neuropathic pain"],["Trazodone","Priapism risk, used for insomnia"],["Venlafaxine","Can increase blood pressure at higher doses"],["Sertraline","Safest in cardiac disease"]]

Clozapine requires monitoring of {{1}} (absolute neutrophil count) initially {{2}} for the first 6 months due to risk of {{3}}.

["ANC","weekly","agranulocytosis"]

Antidepressant & Antipsychotic Selection

Choose SSRIs as first-line for depression/anxiety, manage sexual dysfunction and activation; select atypicals for schizophrenia with metabolic monitoring.

Last generated Jan 2, 2026 UTC

Antidepressant & Antipsychotic Selection

Master antidepressant and antipsychotic selection with free flashcards and evidence-based protocols. This lesson covers medication selection algorithms, safety monitoring parameters, and high-yield drug interactions—essential concepts for NAPLEX success and safe psychiatric practice.

🧠 Welcome to Psychiatric Medication Selection

Psychiatric pharmacotherapy requires careful consideration of efficacy, safety profiles, drug interactions, and patient-specific factors. This lesson focuses on the systematic approach to selecting antidepressants and antipsychotics while minimizing adverse effects and maximizing therapeutic outcomes.

Why This Matters for NAPLEX:

High-frequency topic on the exam
Requires integration of pharmacology, pathophysiology, and patient assessment
Safety monitoring is heavily tested
Drug interactions are a common pitfall

💡 Pro Tip: The NAPLEX emphasizes safety first—always consider contraindications, monitoring parameters, and drug interactions before efficacy.

📊 Core Concepts: Antidepressant Selection

First-Line Antidepressants: SSRIs and SNRIs

Selective Serotonin Reuptake Inhibitors (SSRIs) are typically first-line due to favorable safety profiles and tolerability.

<table> <tr> <th>Drug</th> <th>Key Features</th> <th>Important Considerations</th> </tr> <tr> <td>Sertraline</td> <td>• Broad FDA indications • Minimal drug interactions • Linear kinetics</td> <td>• Safe in cardiac disease • Mild GI side effects • Pregnancy Category C</td> </tr> <tr> <td>Escitalopram</td> <td>• Most selective SSRI • Rapid onset • Well-tolerated</td> <td>• QT prolongation at >20 mg • Avoid in long QT syndrome • Lower max dose in elderly (10 mg)</td> </tr> <tr> <td>Fluoxetine</td> <td>• Longest half-life (4-6 days) • Active metabolite (norfluoxetine) • Less withdrawal</td> <td>• Strong CYP2D6 inhibitor • 5-week washout for MAOIs • May cause activation/insomnia</td> </tr> <tr> <td>Paroxetine</td> <td>• Most anticholinergic • Sedating • Short half-life</td> <td>• Pregnancy Category D • Highest discontinuation syndrome • Weight gain • Strong CYP2D6 inhibitor</td> </tr> <tr> <td>Citalopram</td> <td>• Minimal P450 effects • Predictable dosing</td> <td>• QT prolongation risk • Max dose: 40 mg (20 mg if >60 yo) • ECG if cardiac risk factors</td> </tr> </table>

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) add noradrenergic activity:

<table> <tr> <th>Drug</th> <th>Unique Features</th> <th>Clinical Pearls</th> </tr> <tr> <td>Venlafaxine</td> <td>• Dose-dependent mechanism • Low: SSRI activity • High: SNRI activity</td> <td>• Monitor BP (especially >150 mg/day) • Effective for GAD, social anxiety • Must taper to avoid discontinuation</td> </tr> <tr> <td>Duloxetine</td> <td>• FDA approved for neuropathic pain • Balanced 5-HT/NE reuptake</td> <td>• Avoid in hepatic impairment • Monitor LFTs • Useful for diabetic neuropathy + depression</td> </tr> <tr> <td>Desvenlafaxine</td> <td>• Active metabolite of venlafaxine • No dose titration needed • Renal elimination</td> <td>• Dose adjust in renal impairment • Less BP elevation than venlafaxine • Fixed dosing (50 mg)</td> </tr> </table>

🧠 Mnemonic - SSRI Side Effects: SSCARED

Serotonin syndrome risk
Sexual dysfunction (60-70%)
CNS effects (headache, insomnia)
Activation/anxiety initially
Restlessness/akathisia
Electrolyte (SIADH/hyponatremia)
Discontinuation syndrome

Alternative Antidepressants

<table> <tr> <th>Class/Drug</th> <th>Mechanism</th> <th>Best For</th> <th>Key Safety Issues</th> </tr> <tr> <td>Bupropion (NDRI)</td> <td>Dopamine & norepinephrine reuptake inhibition</td> <td>• SSRI sexual dysfunction • Smoking cessation • Seasonal affective disorder • ADHD + depression</td> <td>⚠️ Lowers seizure threshold • Contraindicated: seizure disorder, eating disorders, abrupt alcohol/benzo withdrawal • No sexual dysfunction • No weight gain</td> </tr> <tr> <td>Mirtazapine (Tetracyclic)</td> <td>α2-antagonist, 5-HT2/5-HT3 antagonist</td> <td>• Depression with insomnia • Poor appetite/weight loss • Nausea</td> <td>• Sedation (inverse dose-related) • Weight gain (H1 antagonism) • Increased appetite • Monitor CBC (rare agranulocytosis)</td> </tr> <tr> <td>Trazodone (SARI)</td> <td>5-HT2A antagonist, weak SSRI</td> <td>• Insomnia (25-100 mg HS) • Depression with insomnia</td> <td>⚠️ Priapism (rare but serious) • Orthostatic hypotension • Sedation (α1-blockade) • Use low doses for sleep</td> </tr> <tr> <td>Vilazodone/Vortioxetine</td> <td>SSRI + 5-HT receptor modulation</td> <td>• Depression with cognitive symptoms • Less sexual dysfunction</td> <td>• Take with food (vilazodone) • Nausea common initially • More expensive than generics</td> </tr> </table>

MAOIs: Last-Line But High-Yield for NAPLEX

Monoamine Oxidase Inhibitors require extensive dietary restrictions but are effective for treatment-resistant depression.

<div style="border: 2px solid #ff6b6b; border-radius: 8px; padding: 16px; margin: 16px 0; background: rgba(255, 107, 107, 0.1);"> <h4>⚠️ CRITICAL SAFETY: MAOI Restrictions</h4>

Tyramine-Rich Foods to AVOID:

Aged cheeses (cheddar, blue, parmesan)
Cured/processed meats (salami, pepperoni, hot dogs)
Fermented foods (sauerkraut, kimchi, soy sauce)
Draft beer, red wine, vermouth
Fava beans, overripe bananas
Yeast extracts (Marmite, Bovril)

Drug Interactions:

⛔ NO SSRIs/SNRIs/TCAs (serotonin syndrome risk)
⛔ NO meperidine (hyperpyrexia, death reported)
⛔ NO sympathomimetics (pseudoephedrine, phenylephrine → hypertensive crisis)
⛔ NO dextromethorphan (serotonin syndrome)

Washout Periods:

SSRI/SNRI to MAOI: 2 weeks (5 weeks for fluoxetine)
MAOI to SSRI/SNRI: 2 weeks </div>

<table> <tr> <th>MAOI</th> <th>Type</th> <th>Notes</th> </tr> <tr> <td>Phenelzine</td> <td>Non-selective, irreversible</td> <td>• Most evidence for atypical depression • Requires strict dietary adherence</td> </tr> <tr> <td>Tranylcypromine</td> <td>Non-selective, irreversible</td> <td>• Amphetamine-like structure • May cause insomnia • Faster onset than phenelzine</td> </tr> <tr> <td>Selegiline patch</td> <td>MAO-B selective (at low doses)</td> <td>• 6 mg patch: no dietary restrictions • ≥9 mg: dietary restrictions apply • Application site reactions</td> </tr> </table>

🎯 Antidepressant Selection Algorithm

<pre> ┌─────────────────────────────────────────────────────────────┐ │ MAJOR DEPRESSIVE DISORDER TREATMENT │ └─────────────────────────────────────────────────────────────┘ │ ▼ ┌───────────────────────────────┐ │ Patient Assessment │ │ • Symptom profile │ │ • Comorbidities │ │ • Prior treatments │ │ • Drug interactions │ │ • Pregnancy status │ └───────────┬───────────────────┘ │ ┌───────────────┼───────────────┐ ▼ ▼ ▼ ┌───────────────┐ ┌──────────────┐ ┌─────────────────┐ │ FIRST-LINE │ │ SPECIAL │ │ AVOID │ │ • SSRI │ │ SITUATIONS │ │ • MAOIs (1st) │ │ • SNRI │ │ │ │ • TCAs (1st) │ │ │ │ │ │ │ │ Consider: │ │ │ │ │ │ Sertraline │ │ │ │ │ │ Escitalopram │ │ │ │ │ └───────┬───────┘ └──────┬───────┘ └─────────────────┘ │ │ │ ▼ │ ┌──────────────────────────────────┐ │ │ Insomnia? → Mirtazapine │ │ │ Sexual dysfunction? → Bupropion │ │ │ Neuropathic pain? → Duloxetine │ │ │ Smoking cessation? → Bupropion │ │ │ Atypical features? → SNRI/MAOI │ │ └──────────────────────────────────┘ │ ▼ ┌─────────────────────────────────────────┐ │ Trial for 4-8 weeks at therapeutic dose│ └─────────────┬───────────────────────────┘ │ ┌───────┴────────┐ ▼ ▼ ✅ Response ❌ Non-response/Intolerance │ │ ▼ ▼ Continue Switch or Augment 6-12 months • Different class • Add bupropion • Add mirtazapine • Add atypical antipsychotic </pre>

💡 Clinical Pearl: Allow adequate trial duration (4-8 weeks) and therapeutic dosing before declaring treatment failure. Many patients are under-dosed or switched too early.

🧬 Core Concepts: Antipsychotic Selection

First-Generation Antipsychotics (FGAs/Typicals)

Mechanism: D2 dopamine receptor antagonism in all pathways

<table> <tr> <th>Potency</th> <th>Examples</th> <th>Key Features</th> <th>Side Effect Profile</th> </tr> <tr> <td>High Potency</td> <td>• Haloperidol • Fluphenazine • Perphenazine</td> <td>• Low doses effective • Less sedation • Less anticholinergic • Long-acting injectable available</td> <td>⚠️ HIGH EPS risk • Akathisia • Dystonia • Parkinsonism • Tardive dyskinesia (long-term)</td> </tr> <tr> <td>Low Potency</td> <td>• Chlorpromazine • Thioridazine</td> <td>• Higher doses needed • More sedating • More anticholinergic</td> <td>⚠️ HIGH metabolic/cardiovascular risk • Orthostatic hypotension • Sedation • Weight gain • QT prolongation • Anticholinergic effects</td> </tr> </table>

🧠 Mnemonic - High vs Low Potency: "High and Nervous, Low and Slow"

High potency: More EPS (nervous system effects)
Low potency: More sedation/metabolic effects (slow/tired)

Second-Generation Antipsychotics (SGAs/Atypicals)

Mechanism: D2 + 5-HT2A antagonism (and various other receptor activities)

<table> <tr> <th>Drug</th> <th>Unique Features</th> <th>Advantages</th> <th>Key Adverse Effects</th> </tr> <tr> <td>Risperidone</td> <td>• Dose-dependent D2 blockade • Active metabolite (9-OH) • Long-acting injectable available</td> <td>• Effective for positive symptoms • Less expensive • Pediatric approvals</td> <td>⚠️ Dose-related EPS (>6 mg/day) • Hyperprolactinemia (highest risk) • Orthostatic hypotension • Weight gain (moderate)</td> </tr> <tr> <td>Olanzapine</td> <td>• Broad receptor binding • Very effective • Multiple formulations</td> <td>• Excellent efficacy • IM available (agitation) • Low EPS • Minimal prolactin effects</td> <td>⚠️ HIGHEST metabolic risk • Weight gain (7-10 kg average) • Diabetes risk • Dyslipidemia • Sedation</td> </tr> <tr> <td>Quetiapine</td> <td>• Weak D2 binding • Active metabolite (norquetiapine) • XR formulation available</td> <td>• Low EPS risk • FDA approved for bipolar depression • Useful for sleep (low doses) • Minimal prolactin elevation</td> <td>• Sedation (H1 antagonism) • Weight gain (moderate-high) • Metabolic effects • Orthostatic hypotension • Cataracts (monitor in long-term)</td> </tr> <tr> <td>Aripiprazole</td> <td>• D2 partial agonist • Long half-life (75 hrs) • LAI formulations • Active metabolite</td> <td>• LOWEST metabolic risk • Weight neutral • No prolactin elevation • No sedation • Once-monthly injection available</td> <td>⚠️ Akathisia (20-25%) • Activation/insomnia • Nausea initially • May worsen agitation initially</td> </tr> <tr> <td>Ziprasidone</td> <td>• 5-HT/NE reuptake inhibition • BID dosing • Take with food (↑absorption)</td> <td>• Weight neutral • Low metabolic risk • May improve depressive symptoms</td> <td>⚠️ QTc prolongation • Must take with ≥500 cal meal • Moderate EPS • Activation/anxiety</td> </tr> <tr> <td>Lurasidone</td> <td>• Take with food (≥350 cal) • Renal/hepatic dose adjustment • Once daily</td> <td>• Weight neutral • Low metabolic risk • FDA approved for bipolar depression • Low sedation</td> <td>• Akathisia • Nausea • Must take with food • More expensive</td> </tr> <tr> <td>Clozapine</td> <td>• GOLD STANDARD for treatment-resistant schizophrenia • Weak D2 binding • Requires REMS program</td> <td>• Most effective antipsychotic • Reduces suicide risk • Lowest EPS • No tardive dyskinesia • No prolactin elevation</td> <td>⚠️ AGRANULOCYTOSIS (1-2%) • Requires weekly → biweekly ANC monitoring • Seizures (dose-related, 5%) • Myocarditis • Severe constipation • Hypersalivation • Highest metabolic risk • Sedation</td> </tr> </table>

<div style="border: 2px solid #ff6b6b; border-radius: 8px; padding: 16px; margin: 16px 0; background: rgba(255, 107, 107, 0.1);"> <h4>⚠️ CLOZAPINE MONITORING REQUIREMENTS</h4>

Absolute Neutrophil Count (ANC) Monitoring:

<table> <tr> <th>Timeframe</th> <th>Frequency</th> </tr> <tr> <td>Weeks 1-26</td> <td>Weekly ANC</td> </tr> <tr> <td>Months 7-12</td> <td>Every 2 weeks</td> </tr> <tr> <td>Month 12+</td> <td>Monthly</td> </tr> </table>

Action Based on ANC:

ANC ≥1500: Continue treatment
ANC 1000-1499: Monitor 3x weekly
ANC <1000: DISCONTINUE immediately
ANC <500: CONTRAINDICATED permanently

Other Monitoring:

Baseline ECG, lipids, glucose, weight
Metabolic monitoring every 3 months
Assess for constipation (can be fatal)
Monitor for signs of myocarditis (first month) </div>

🎯 Antipsychotic Selection Algorithm

<pre> ┌──────────────────────────────────────────────────────────┐ │ SCHIZOPHRENIA TREATMENT │ └──────────────────────────────────────────────────────────┘ │ ▼ ┌────────────────────────────────┐ │ Patient Assessment │ │ • First episode vs chronic │ │ • Metabolic risk factors │ │ • Previous trials/response │ │ • Side effect history │ │ • Adherence concerns │ └────────────┬───────────────────┘ │ ┌────────────────┼────────────────┐ ▼ ▼ ▼ ┌─────────┐ ┌──────────┐ ┌────────────┐ │ FIRST │ │ SPECIAL │ │ LAST LINE │ │ EPISODE │ │ CONCERNS │ │ │ └────┬────┘ └─────┬────┘ └──────┬─────┘ │ │ │ ▼ ▼ ▼ ┌─────────────┐ ┌────────────────┐ ┌──────────┐ │ Prefer SGA │ │ Metabolic risk?│ │ Clozapine│ │ Lower dose │ │ → Aripiprazole │ │ (2+ failed│ │ Avoid high │ │ → Ziprasidone │ │ trials) │ │ metabolic │ │ → Lurasidone │ │ │ │ risk agents │ │ │ │ Requires │ │ │ │ Adherence issue│ │ REMS │ │ │ │ → LAI (long- │ │ Weekly → │ │ │ │ acting inj) │ │ Monthly │ │ │ │ │ │ ANC │ └─────────────┘ └────────────────┘ └──────────┘ </pre>

💡 NAPLEX High-Yield: Know which antipsychotics are available as long-acting injectables (LAIs):

FGAs: Haloperidol decanoate, fluphenazine decanoate (q2-4 weeks)
SGAs: Risperidone (Risperdal Consta, q2 weeks), Paliperidone (Invega Sustenna/monthly, Trinza/q3 months), Aripiprazole (Abilify Maintena/Aristada, monthly), Olanzapine (Zyprexa Relprevv, q2-4 weeks)

📋 Examples with Clinical Application

Example 1: SSRI Selection in Cardiac Patient

Case: 68-year-old male with major depression and history of MI 6 months ago. Current medications include aspirin, metoprolol, atorvastatin, lisinopril. No other psychiatric history.

Analysis:

<table> <tr> <th>Step</th> <th>Consideration</th> <th>Decision</th> </tr> <tr> <td>1</td> <td>First-line for depression</td> <td>SSRI or SNRI appropriate</td> </tr> <tr> <td>2</td> <td>Cardiac safety</td> <td>Avoid citalopram/escitalopram (QT risk at higher doses) SNRIs increase BP (avoid venlafaxine)</td> </tr> <tr> <td>3</td> <td>Drug interactions</td> <td>Metoprolol metabolized by CYP2D6 Avoid strong 2D6 inhibitors (fluoxetine, paroxetine)</td> </tr> <tr> <td>4</td> <td>Best choice</td> <td>Sertraline - cardiac safe, minimal drug interactions, linear kinetics</td> </tr> </table>

Recommendation: Sertraline 50 mg daily, titrate to 100-150 mg as needed. Monitor for GI upset initially. Safe with cardiac medications.

⚠️ Common Mistake: Starting citalopram 40 mg in elderly cardiac patient → QT prolongation risk. Maximum dose is 20 mg in patients >60 years old.

Example 2: Managing SSRI Sexual Dysfunction

Case: 32-year-old female with good response to escitalopram 20 mg for depression (8 months), but reports decreased libido and anorgasmia. Depression is in remission. She wants to continue medication.

Options:

<table> <tr> <th>Strategy</th> <th>Mechanism</th> <th>Evidence</th> <th>Considerations</th> </tr> <tr> <td>Switch to bupropion</td> <td>No serotonergic activity DA/NE reuptake inhibition</td> <td>⭐⭐⭐ Strong No sexual dysfunction May improve libido</td> <td>• Risk of relapse when switching • 2-week taper recommended • May cause activation/insomnia</td> </tr> <tr> <td>Add bupropion</td> <td>Dopamine augmentation May counteract 5-HT effects</td> <td>⭐⭐⭐ Strong Maintains antidepressant effect Improves sexual function</td> <td>• BEST OPTION • Bupropion XL 150-300 mg AM • No relapse risk • Synergistic antidepressant effect</td> </tr> <tr> <td>Add sildenafil PRN</td> <td>PDE-5 inhibition Increases blood flow</td> <td>⭐⭐ Moderate Works in males>females Addresses arousal/erectile issues</td> <td>• Take 1 hour before activity • Doesn't address libido • More effective for arousal than desire</td> </tr> <tr> <td>Drug holiday</td> <td>Temporary SSRI discontinuation</td> <td>⭐ Weak Not recommended</td> <td>❌ AVOID • Risk of discontinuation syndrome • Risk of relapse • Not practical long-term</td> </tr> </table>

Recommendation: Add bupropion XL 150 mg AM, increase to 300 mg after 1 week. Continue escitalopram 20 mg. Reassess in 4-6 weeks.

💡 Pro Tip: Sexual dysfunction occurs in 60-70% of SSRI/SNRI patients. Always ask about it proactively, as patients often don't volunteer this information due to embarrassment.

Example 3: First-Episode Psychosis in Young Adult

Case: 19-year-old male college student with first episode of psychosis (auditory hallucinations, paranoid delusions). No substance use confirmed. BMI 22, no medical conditions. Family history of type 2 diabetes (mother).

Selection Priorities:

Efficacy - need good symptom control
Metabolic profile - young patient, diabetes family history
Tolerability - first episode, adherence critical
Cognitive effects - college student

<table> <tr> <th>Option</th> <th>Pros</th> <th>Cons</th> <th>Rating</th> </tr> <tr> <td>Olanzapine</td> <td>• Excellent efficacy • Low EPS • Evidence in first episode</td> <td>❌ Highest metabolic risk • 7-10 kg weight gain average • Diabetes risk with family history • Sedation affects academics</td> <td>⚠️ AVOID (metabolic concerns)</td> </tr> <tr> <td>Risperidone</td> <td>• Good efficacy • Well-studied • Lower cost</td> <td>⚠️ Dose-related EPS • Hyperprolactinemia • Moderate metabolic effects • Gynecomastia risk in males</td> <td>⚠️ Consider (watch dose/prolactin)</td> </tr> <tr> <td>Aripiprazole</td> <td>✅ Weight neutral ✅ No metabolic effects ✅ No prolactin elevation ✅ No sedation • Good efficacy</td> <td>• Akathisia (20-25%) • May cause activation • Longer titration</td> <td>✅ BEST CHOICE (ideal profile for this patient)</td> </tr> <tr> <td>Lurasidone</td> <td>• Weight neutral • Low metabolic risk • Low sedation</td> <td>• Must take with food • More expensive • Less long-term data</td> <td>✅ Good alternative</td> </tr> </table>

Recommendation:

Aripiprazole 5-10 mg daily, titrate to 10-15 mg over 2 weeks
Monitoring: Weight, waist circumference, fasting glucose, lipids at baseline and every 3 months
Counsel: May experience restlessness (akathisia) - treatable with dose reduction or propranolol if needed
Duration: Minimum 1-2 years for first episode, possibly longer

🧠 Clinical Pearl: In first-episode psychosis, metabolic-friendly agents (aripiprazole, lurasidone, ziprasidone) should be strongly favored. Early weight gain predicts long-term metabolic complications and is a major cause of non-adherence in young patients.

Example 4: Treatment-Resistant Depression

Case: 45-year-old female with MDD, failed adequate trials of:

Sertraline 200 mg × 8 weeks
Venlafaxine XR 225 mg × 10 weeks
Duloxetine 120 mg × 8 weeks

All trials had adequate duration at therapeutic doses. Partial response to each but persistent symptoms (PHQ-9 score remains 15-18).

Augmentation Strategies:

<table> <tr> <th>Strategy</th> <th>Evidence Level</th> <th>Mechanism</th> <th>Key Points</th> </tr> <tr> <td>Add aripiprazole</td> <td>⭐⭐⭐⭐ FDA approved Multiple RCTs</td> <td>D2 partial agonist 5-HT1A agonist 5-HT2A antagonist</td> <td>• Start 2-5 mg daily • Effective dose: 5-15 mg • Response in 1-2 weeks • Watch for akathisia • Weight neutral</td> </tr> <tr> <td>Add quetiapine XR</td> <td>⭐⭐⭐⭐ FDA approved Strong evidence</td> <td>Norquetiapine (metabolite): NE reuptake inhibition</td> <td>• Dose: 150-300 mg HS • Sedating (bedtime dosing) • ⚠️ Weight gain • ⚠️ Metabolic effects</td> </tr> <tr> <td>Add bupropion</td> <td>⭐⭐⭐ Good evidence Common practice</td> <td>DA/NE reuptake inhibition Complements serotonergic agents</td> <td>• Bupropion XL 150-300 mg • May improve energy/motivation • No metabolic effects • Addresses sexual dysfunction</td> </tr> <tr> <td>Add lithium</td> <td>⭐⭐⭐ Strong evidence Oldest augmentation</td> <td>Enhances serotonin transmission</td> <td>• Target level: 0.6-0.8 mEq/L • Requires monitoring (level, TSH, Cr) • Narrow therapeutic index • Drug interactions</td> </tr> <tr> <td>Switch to MAOI</td> <td>⭐⭐⭐ Effective for TRD</td> <td>Increases all monoamines</td> <td>• Requires 2-week washout • Dietary restrictions • Reserve for refractory cases • Consider after 2-3 failed trials</td> </tr> </table>

Recommendation for this patient: Add aripiprazole 5 mg daily, increase to 10 mg after 1 week. Continue current duloxetine. This provides:

✅ FDA-approved indication
✅ Rapid onset (1-2 weeks vs 4-6 weeks for other strategies)
✅ Favorable metabolic profile
✅ Can stay on current effective SNRI

Alternative if sedation/sleep is an issue: Add quetiapine XR 150 mg HS, increase to 300 mg after 3-4 days.

⚠️ Common Mistakes in Psychiatric Medication Selection

Mistake #1: Not Considering Drug Interactions

Scenario: Prescribing fluoxetine to patient on tamoxifen for breast cancer.

Why it's wrong:

Fluoxetine is a strong CYP2D6 inhibitor
Tamoxifen is a prodrug requiring 2D6 conversion to active endoxifen
Result: ⚠️ Reduced tamoxifen efficacy → increased cancer recurrence risk

Correct approach: Use antidepressants with minimal 2D6 inhibition:

✅ Venlafaxine
✅ Citalopram/escitalopram
✅ Sertraline (weak inhibition at low doses)

💡 NAPLEX Tip: Strong CYP2D6 inhibitors = "FPP" - Fluoxetine, Paroxetine, buproPion

Mistake #2: Inadequate Trial Duration/Dose

Scenario: Switching antidepressants after 2 weeks at starting dose because "it's not working."

Why it's wrong:

Antidepressants require 4-8 weeks at therapeutic dose for full effect
Partial response at 2-4 weeks often predicts eventual response
Premature switching → prolonged suffering, polypharmacy

Correct approach: <table> <tr> <th>Week</th> <th>Action</th> <th>Expected Response</th> </tr> <tr> <td>1-2</td> <td>Start at initial dose Assess tolerability</td> <td>Side effects appear Minimal therapeutic effect</td> </tr> <tr> <td>3-4</td> <td>Titrate to therapeutic dose</td> <td>Side effects diminish Early improvement (energy, sleep)</td> </tr> <tr> <td>4-6</td> <td>Maintain therapeutic dose</td> <td>Mood improvement begins Partial response</td> </tr> <tr> <td>6-8</td> <td>Assess full response</td> <td>Maximum benefit achieved Decision point: continue, increase, or switch</td> </tr> </table>

Mistake #3: Ignoring Metabolic Monitoring with Antipsychotics

Scenario: Patient on olanzapine for 6 months, no metabolic monitoring done.

Why it's wrong:

SGAs (especially olanzapine, clozapine, quetiapine) cause significant metabolic effects
Weight gain, diabetes, dyslipidemia develop insidiously
Cardiovascular disease is leading cause of death in schizophrenia patients

Required monitoring schedule:

<table> <tr> <th>Parameter</th> <th>Baseline</th> <th>Month 1</th> <th>Month 2</th> <th>Month 3</th> <th>Quarterly</th> <th>Annually</th> </tr> <tr> <td>Weight/BMI</td> <td>✅</td> <td>✅</td> <td>✅</td> <td>✅</td> <td>✅</td> <td>✅</td> </tr> <tr> <td>Waist circumference</td> <td>✅</td> <td></td> <td></td> <td></td> <td></td> <td>✅</td> </tr> <tr> <td>Blood pressure</td> <td>✅</td> <td></td> <td></td> <td>✅</td> <td>✅</td> <td>✅</td> </tr> <tr> <td>Fasting glucose</td> <td>✅</td> <td></td> <td></td> <td>✅</td> <td>✅</td> <td>✅</td> </tr> <tr> <td>Fasting lipids</td> <td>✅</td> <td></td> <td></td> <td>✅</td> <td>✅</td> <td>✅</td> </tr> </table>

Action thresholds:

Weight gain >5% baseline → Consider switching to metabolic-neutral agent
Fasting glucose >100 mg/dL → Lifestyle intervention, consider metformin
Fasting glucose >126 mg/dL → Diagnose diabetes, treat appropriately
LDL >130 mg/dL → Consider statin therapy

Mistake #4: Using QT-Prolonging Combinations

Scenario: Patient on citalopram 60 mg + haloperidol + methadone

Why it's wrong:

All three agents prolong QT interval
Additive effect → risk of Torsades de Pointes (potentially fatal arrhythmia)
Citalopram 60 mg exceeds maximum dose (40 mg)

High-risk QT-prolonging psychiatric medications:

<div style="border: 2px solid #ff6b6b; border-radius: 8px; padding: 16px; margin: 16px 0; background: rgba(255, 107, 107, 0.1);"> <h4>⚠️ MAJOR QT PROLONGATION RISK</h4>

Antipsychotics:

Thioridazine (BLACK BOX - contraindicated in QT >450 ms)
Ziprasidone
Haloperidol (IV > PO)
Quetiapine
Olanzapine (lower risk)

Antidepressants:

Citalopram (dose-dependent, >40 mg)
Escitalopram (dose-dependent, >20 mg)
TCAs (especially at toxic levels)

Risk factors requiring ECG:

Personal/family history of long QT
Cardiac disease
Electrolyte abnormalities (↓K, ↓Mg, ↓Ca)
Bradycardia
Concurrent QT-prolonging drugs
Age >65 years </div>

Correct approach:

Reduce citalopram to ≤40 mg (≤20 mg if >60 yo)
Consider switching to sertraline (no QT effect)
Obtain baseline and follow-up ECG
Check electrolytes

Mistake #5: Abrupt Discontinuation of Antidepressants

Scenario: Patient stops paroxetine 40 mg abruptly after 6 months of treatment.

Result: Severe discontinuation syndrome within 24-48 hours:

Dizziness, vertigo
"Brain zaps" (electric shock sensations)
Flu-like symptoms (fatigue, myalgia, chills)
Insomnia, vivid dreams
Nausea
Irritability, anxiety
Crying spells

Why paroxetine is worst:

Shortest half-life among SSRIs (~21 hours)
No active metabolites
Strong anticholinergic rebound

Risk ranking for discontinuation syndrome:

Highest risk: Paroxetine, venlafaxine (short half-life, no active metabolites)
Moderate risk: Sertraline, citalopram, escitalopram, duloxetine
Low risk: Fluoxetine (long half-life + active metabolite), bupropion

Proper taper schedule:

<table> <tr> <th>Original Dose</th> <th>Week 1-2</th> <th>Week 3-4</th> <th>Week 5-6</th> <th>Week 7+</th> </tr> <tr> <td>Paroxetine 40 mg</td> <td>30 mg</td> <td>20 mg</td> <td>10 mg</td> <td>Discontinue</td> </tr> <tr> <td>Venlafaxine 225 mg</td> <td>150 mg</td> <td>75 mg</td> <td>37.5 mg</td> <td>Discontinue</td> </tr> </table>

💡 Exception: Fluoxetine can often be stopped without taper due to long half-life (4-6 days) and active metabolite norfluoxetine (4-16 days).

🎯 Key Takeaways

<div style="border: 2px solid #4fd1c5; border-radius: 8px; padding: 16px; margin: 16px 0; background: rgba(79, 209, 197, 0.1);"> <h4>📋 Quick Reference Card: Antidepressant Selection</h4>

<table> <tr> <th>Clinical Situation</th> <th>Best Choice</th> <th>Avoid</th> </tr> <tr> <td>First-line MDD</td> <td>Sertraline, escitalopram</td> <td>MAOIs, TCAs</td> </tr> <tr> <td>Cardiac disease</td> <td>Sertraline</td> <td>Citalopram >20-40 mg, TCAs, venlafaxine</td> </tr> <tr> <td>Elderly patient</td> <td>Sertraline, citalopram ≤20 mg</td> <td>Paroxetine (anticholinergic), TCAs</td> </tr> <tr> <td>Sexual dysfunction</td> <td>Bupropion (switch or add)</td> <td>Increasing SSRI/SNRI dose</td> </tr> <tr> <td>Insomnia prominent</td> <td>Mirtazapine</td> <td>Bupropion, fluoxetine</td> </tr> <tr> <td>Weight loss desired</td> <td>Bupropion</td> <td>Mirtazapine, paroxetine</td> </tr> <tr> <td>Neuropathic pain + MDD</td> <td>Duloxetine</td> <td>Bupropion (no pain effect)</td> </tr> <tr> <td>Smoking cessation + MDD</td> <td>Bupropion</td> <td>N/A</td> </tr> <tr> <td>Pregnancy</td> <td>Sertraline (most data)</td> <td>Paroxetine (Category D)</td> </tr> <tr> <td>On tamoxifen</td> <td>Venlafaxine, citalopram</td> <td>Fluoxetine, paroxetine (2D6 inhibitors)</td> </tr> </table>

🧠 Remember:

SSRI side effects = SSCARED (Serotonin syndrome, Sexual dysfunction, CNS effects, Activation, Restlessness, Electrolyte/SIADH, Discontinuation)
Bupropion contraindications: Seizures, eating disorders, abrupt alcohol/benzo withdrawal
MAOIs: 2-week washout (5 weeks for fluoxetine), avoid tyramine-rich foods </div>

<div style="border: 2px solid #4fd1c5; border-radius: 8px; padding: 16px; margin: 16px 0; background: rgba(79, 209, 197, 0.1);"> <h4>📋 Quick Reference Card: Antipsychotic Selection</h4>

<table> <tr> <th>Clinical Situation</th> <th>Best Choice</th> <th>Avoid</th> </tr> <tr> <td>First-episode psychosis</td> <td>Aripiprazole, lurasidone (metabolic-friendly)</td> <td>Olanzapine, clozapine</td> </tr> <tr> <td>Metabolic risk factors</td> <td>Aripiprazole, ziprasidone, lurasidone</td> <td>Olanzapine, clozapine</td> </tr> <tr> <td>Non-adherence concern</td> <td>Long-acting injectable (LAI)</td> <td>Multiple daily dosing</td> </tr> <tr> <td>Treatment-resistant (2+ failures)</td> <td>Clozapine</td> <td>Continuing same failed strategies</td> </tr> <tr> <td>Elderly patient</td> <td>Low-dose quetiapine, aripiprazole</td> <td>High-potency FGAs, high-dose SGAs</td> </tr> <tr> <td>Parkinson's disease + psychosis</td> <td>Quetiapine, pimavanserin</td> <td>All other antipsychotics (worsen EPS)</td> </tr> <tr> <td>Acute agitation</td> <td>IM olanzapine, IM ziprasidone, IM aripiprazole</td> <td>Oral medications (slower onset)</td> </tr> <tr> <td>Bipolar depression</td> <td>Quetiapine, lurasidone, cariprazine</td> <td>Antidepressant monotherapy</td> </tr> <tr> <td>Cardiac disease</td> <td>Aripiprazole, risperidone (low dose)</td> <td>Ziprasidone, thioridazine</td> </tr> </table>

🧠 Remember:

Metabolic rank (worst to best): Clozapine = Olanzapine > Quetiapine > Risperidone > Aripiprazole = Ziprasidone = Lurasidone
EPS rank (highest to lowest): High-potency FGAs (haloperidol) > Low-potency FGAs > Risperidone > Olanzapine/Quetiapine > Aripiprazole > Clozapine
Prolactin elevation: Risperidone > Paliperidone > FGAs >> Others (minimal)
"High and Nervous, Low and Slow" - High-potency FGAs → more EPS, Low-potency FGAs → more sedation/metabolic </div>

<div style="border: 2px solid #ff6b6b; border-radius: 8px; padding: 16px; margin: 16px 0; background: rgba(255, 107, 107, 0.1);"> <h4>⚠️ Critical Safety Points for NAPLEX</h4>

Antidepressants:

Black Box Warning: Increased suicidality in patients <25 years old (especially first 1-2 months)
Serotonin syndrome: Risk with combinations (SSRI + MAOI, SSRI + tramadol, SSRI + linezolid). Triad = altered mental status + autonomic instability + neuromuscular hyperactivity
QT prolongation: Citalopram >40 mg, escitalopram >20 mg - obtain ECG if risk factors
Discontinuation syndrome: Taper all antidepressants except fluoxetine. Worst offenders: paroxetine, venlafaxine
SIADH/hyponatremia: Higher risk in elderly, on diuretics. Check sodium if symptoms (confusion, falls, seizures)
Bleeding risk: SSRIs impair platelet aggregation. Caution with NSAIDs, anticoagulants, antiplatelet agents

Antipsychotics:

Black Box Warning: Increased mortality in elderly patients with dementia-related psychosis
Clozapine agranulocytosis: Weekly ANC monitoring (weeks 1-26), then biweekly (months 7-12), then monthly. Discontinue if ANC <1000
Metabolic syndrome: Baseline + regular monitoring (weight, glucose, lipids). Most weight gain occurs in first 6 months
Neuroleptic malignant syndrome (NMS): Rare but life-threatening. Features = fever, rigidity, altered mental status, autonomic instability, elevated CK. Stop antipsychotic immediately
Tardive dyskinesia: Involuntary movements (tongue, lips, face) from chronic dopamine blockade. May be irreversible. Higher risk with FGAs, elderly, females, longer duration
QT prolongation: Highest risk with thioridazine, ziprasidone, IV haloperidol. Obtain ECG at baseline if risk factors </div>

📚 Further Study

American Psychiatric Association - Practice Guidelines for Major Depressive Disorder
https://www.psychiatry.org/psychiatrists/practice/clinical-practice-guidelines
NAPLEX Competency Statements (Psychiatric Disorders Section)
https://nabp.pharmacy/programs/naplex/
Stahl's Essential Psychopharmacology Online - Antidepressants and Antipsychotics
https://stahlonline.cambridge.org/

🎯 You've completed Antidepressant & Antipsychotic Selection! You now have the framework to systematically choose psychiatric medications based on efficacy, safety, and patient-specific factors. Remember: NAPLEX emphasizes safety monitoring and drug interactions - master these and you'll excel!

Next Steps:

Review flashcards daily using spaced repetition
Practice case-based questions
Create your own clinical scenarios
Master monitoring parameters for high-risk agents

Good luck on your NAPLEX journey! 💊🧠

📝

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