Antidepressants: SSRIs, SNRIs, Atypical Antidepressants, MAOIs

Drug Names & Dosing

1. SSRIs

• Sertraline: 50 mg PO OD, ↑ to 100 mg after 7 days (max 200 mg)

• Escitalopram: 10 mg PO OD (max 20 mg)

• Fluoxetine: 20 mg PO OD (max 60 mg)

• Fluvoxamine: 50–100 mg PO OD (max 300 mg in divided doses)

• Citalopram: 20 mg PO OD (max 40 mg; max 20 mg if >65 years due to QTc risk)

• Paroxetine: 20 mg PO OD (max 50 mg)

2. SNRIs

• Duloxetine: 60 mg PO OD (max 120 mg)

• Venlafaxine XR: 75 mg PO OD (max 375 mg; monitor BP at higher doses)

• Desvenlafaxine XR: 50 mg PO OD (max 200 mg)

• Reboxetine: 4 mg PO BD (max 12 mg; second-line)

3. Atypical Antidepressants

• Mirtazapine: 15–30 mg PO nocte (max 60 mg; lower doses more sedating)

• Agomelatine: 25 mg PO nocte (max 50 mg; requires LFT monitoring)

4. MAOIs

• Selegiline: 5 mg PO BD (also for Parkinson’s disease)

• Phenelzine: 15 mg PO TDS (max 90 mg; irreversible, non-selective)

• Moclobemide: 150 mg PO BD (max 600 mg; reversible MAOI-A, second-line)

Pharmacological Considerations

• First-Line Options: SSRIs, SNRIs, mirtazapine

• Second-Line: MAOIs, reboxetine (due to safety/tolerability concerns)

• MAOIs: Risk of hypertensive crisis with dietary tyramine (e.g., aged cheese, cured meats)

Special Populations:

• Elderly: SSRIs preferred; avoid citalopram (>65 years) due to QTc prolongation risk

• SNRIs: Venlafaxine may ↑ BP at higher doses → monitor BP

• Mirtazapine: Useful for insomnia or poor appetite

Monitoring & Interactions

1. SSRIs/SNRIs

• Monitor for serotonin syndrome with other serotonergic drugs (e.g., tramadol, linezolid)

• Regular BP checks for venlafaxine (high doses)

2. MAOIs

• Dietary Restrictions: Avoid tyramine-rich foods to prevent hypertensive crisis

• Washout Periods: Strict when switching to/from other antidepressants to avoid serotonin syndrome or hypertensive crisis

3. Additional Monitoring

• Monitor for weight changes

• LFTs: Periodic monitoring for agomelatine

• BP: Regular checks, especially with venlafaxine or SNRIs at high

Notes

• Antidepressants are typically dosed once daily (OD) unless specified

• Educate patients on potential interactions and the need for adherence to monitoring schedules

Antidepressants: Considerations When Prescribing

Key Considerations Before Prescribing

1. Symptom Assessment

   • Evaluate severity, duration, and impact on functioning

2. Comorbidities

   • Tailor choice based on coexisting conditions (e.g., anxiety, chronic pain, insomnia)

3. Drug Interactions

   • Review concurrent medications:

     • SSRIs + warfarin: Increased bleeding risk

     • Serotonergic agents (e.g., tramadol): Serotonin syndrome risk

4. Previous Treatments

   • Assess response and tolerability of past antidepressants

5. Patient Profile

   • Consider: Age, pregnancy status, renal/hepatic function, QT prolongation risk

Patient Education Points

1. Starting Treatment

   • Explain dose titration and review plan

2. Onset of Action

   • Improvement typically takes 2–6 weeks

3. Duration of Treatment

   • Minimum 12 months; longer for recurrent depression

4. Side Effects

   • Short-Term (1–2 weeks): Nausea, increased anxiety, possible worsening suicidality (temporary)

   • Long-Term: Weight gain, sexual dysfunction, sedation

5. Alcohol

   • Exacerbates depression and counteracts medication effects → avoid

6. Stopping Antidepressants

   • Warn against abrupt cessation → taper gradually to avoid withdrawal symptoms (e.g., agitation, dizziness, flu-like symptoms)

7. Safety in Pregnancy

   • Avoid paroxetine (congenital malformations); sertraline is preferred

Additional Notes

• Address myths about dependency (antidepressants are not addictive)

• Incorporate CBT or non-pharmacological therapies in the plan

• Monitor for worsening symptoms, especially in:

  • First month of treatment

  • Patients <25 years old