What are the recommended dosages and treatment durations for psychiatric medications in patients with depression, anxiety disorders, and bipolar disorder?

Psychiatric Medication Dosing and Duration

Depression Treatment

For first-episode major depressive disorder, initiate an SSRI at standard starting doses (sertraline 50 mg daily, fluoxetine 20 mg daily, citalopram/escitalopram 20/10 mg daily) and continue treatment for 4-9 months after achieving satisfactory response; patients with recurrent depression (≥2 episodes) require years to lifelong maintenance therapy. 1, 2, 3

Initial Dosing for Depression

• Sertraline: Start 50 mg once daily (morning or evening); this is both the starting and typically effective therapeutic dose 3, 4
• Fluoxetine: Start 20 mg daily; this dose demonstrates full efficacy without requiring titration 5
• Citalopram/Escitalopram: Preferred in elderly patients; citalopram maximum 40 mg/day due to QT prolongation risk 1
• Paroxetine: Generally avoid in elderly due to higher adverse effect rates; associated with increased suicidal ideation risk compared to other SSRIs 1

Dose Titration Strategy

• For non-responders at 50 mg sertraline: Increase in 50 mg increments at ≥1 week intervals up to maximum 200 mg/day, though evidence suggests continued treatment at 50 mg may be as effective as dose escalation 3, 6
• For panic disorder/anxiety: Start lower (sertraline 25 mg daily for 1 week, then increase to 50 mg) as patients may be intolerant of standard starting doses 3, 7
• Dose changes: Should not occur at intervals less than 1 week given sertraline's 24-hour elimination half-life 3

Treatment Duration for Depression

• First episode: Continue 4-9 months after remission to prevent relapse 1, 2
• Recurrent depression (≥2 episodes): Longer duration therapy (years to lifelong) is beneficial 1, 2
• Assessment timeline: Modify treatment if inadequate response within 6-8 weeks of initiation 1
• Monitoring frequency: Assess patient status, therapeutic response, and adverse effects within 1-2 weeks of initiation, then regularly throughout treatment 1

Treatment Response Expectations

• Full therapeutic trial: Requires at least 4-8 weeks at adequate dosing 1
• Response rates: Approximately 50% with first-line SSRI therapy 1
• Remission definition: HAM-D score ≤8 or 50% reduction from baseline 1

Anxiety Disorders Treatment

For pediatric anxiety disorders (ages 6-18), initiate SSRIs at lower starting doses than depression, with sertraline 25 mg daily for one week before increasing to 50 mg daily; combination CBT plus SSRI is preferred over monotherapy for social anxiety, generalized anxiety, separation anxiety, and panic disorder. 1, 3

Pediatric Anxiety Dosing (Ages 6-18)

• Starting doses: Begin conservatively with subtherapeutic "test" dose due to initial anxiety/agitation risk 1
• Sertraline for anxiety: 25 mg daily × 1 week, then increase to 50 mg daily 3
• Titration: Increase in smallest available increments at 1-2 week intervals for shorter half-life SSRIs (sertraline, citalopram) or 3-4 week intervals for longer half-life SSRIs (fluoxetine) 1
• Maximum dose: Up to 200 mg/day sertraline as tolerated, though dose-response relationship not clearly established 3

Adult Anxiety Dosing

• Panic disorder, PTSD, social anxiety: Start sertraline 25 mg daily × 1 week, then 50 mg daily; dose range 50-200 mg/day 3
• Generalized anxiety: No significant efficacy differences among SSRIs (fluoxetine, paroxetine, sertraline, venlafaxine) 1

Combination Therapy for Pediatric Anxiety

• Preferred approach: CBT plus SSRI shows superior outcomes versus either treatment alone for response, remission, and global function 1
• Evidence base: Moderate strength of evidence supporting combination treatment over monotherapy 1

Bipolar Disorder Treatment

For bipolar disorder with agitation or mood instability, initiate divalproex sodium 125 mg twice daily and titrate to therapeutic blood level (40-90 mcg/mL), as it is generally better tolerated than other mood stabilizers; carbamazepine is an alternative starting at 100 mg twice daily titrated to 4-8 mcg/mL. 1

Mood Stabilizer Dosing

• Divalproex sodium (Depakote): Start 125 mg twice daily; titrate to therapeutic level 40-90 mcg/mL; monitor liver enzymes, platelets, PT/PTT 1
• Carbamazepine (Tegretol): Start 100 mg twice daily; titrate to 4-8 mcg/mL; requires CBC and liver enzyme monitoring; has more problematic side effects than divalproex 1

Adjunctive Medications for Bipolar Agitation

• Trazodone: Start 25 mg/day; maximum 200-400 mg/day in divided doses for severe agitation/combativeness 1
• Antipsychotics: Required concomitantly when depression presents with psychotic features 1

Special Populations

Elderly Patients (≥65 years)

• Preferred agents: Citalopram, escitalopram, sertraline, mirtazapine, venlafaxine, bupropion 1
• Avoid: Paroxetine and fluoxetine due to higher adverse effect rates 1
• Dosing: No dose adjustment needed for sertraline in elderly (unlike some other SSRIs) 4

Pediatric Depression (Ages 6-17)

• Obsessive-compulsive disorder: Ages 6-12 start sertraline 25 mg daily; ages 13-17 start 50 mg daily; maximum 200 mg/day 3
• Body weight consideration: Lower body weights in children require careful dose advancement to avoid excess dosing 3

Critical Safety Considerations

Monitoring Requirements

• Suicidality: Highest risk during first 1-2 months; monitor closely for agitation, irritability, unusual behavior changes starting within 1-2 weeks of initiation 1
• Serotonin syndrome: Risk with SSRI overdose (14-16% of cases) or combination with other serotonergic drugs; presents with tremor, diarrhea, delirium, rigidity, hyperthermia 1
• QT prolongation: Citalopram contraindicated >40 mg/day; avoid in long QT syndrome 1

Discontinuation Syndrome

• High-risk agents: Paroxetine > fluvoxamine > sertraline 1
• Symptoms: Dizziness, fatigue, myalgias, nausea, insomnia, paresthesias, anxiety, agitation 1
• Prevention: Taper over 10-14 days when discontinuing 1

Drug Interactions

• MAOIs: Absolute contraindication with all SSRIs due to serotonin syndrome risk 1
• CYP450 interactions: Fluvoxamine has greatest interaction potential (CYP1A2, 2C19, 2C9, 3A4, 2D6); citalopram/escitalopram have least 1

Comparative Efficacy

All second-generation antidepressants demonstrate equivalent efficacy for treatment-naive patients; medication selection should prioritize adverse effect profiles, drug interactions, and patient-specific factors rather than presumed superior efficacy. 1

• No efficacy differences: Among SSRIs for depression, anxiety with depression, insomnia with depression, pain with depression, or across age/sex/race subgroups 1
• Slight advantages: SNRIs (duloxetine, venlafaxine) marginally more effective than SSRIs but with higher nausea/vomiting rates 1
• Melancholia: Limited evidence suggests sertraline superior to fluoxetine, venlafaxine superior to fluoxetine 1