What is the recommended treatment and dosage for major depressive disorder using Remeron (mirtazapine)?

Mirtazapine (Remeron) Treatment for Major Depressive Disorder

For major depressive disorder, mirtazapine (Remeron) should be started at 15 mg/day as a single dose at bedtime, with dose increases up to a maximum of 45 mg/day if needed. 1

Dosing Recommendations

Initial Treatment

• Starting dose: 15 mg/day as a single dose at bedtime 1
• Effective dose range: 15-45 mg/day 2, 1
• Titration: If no response to initial 15 mg dose, increase dose gradually
• Dose adjustment timing: Wait 1-2 weeks between dose changes due to mirtazapine's long half-life (20-40 hours) 1

Special Populations

• Elderly patients: Lower doses recommended due to reduced clearance (40% lower in elderly males, 10% lower in elderly females) 1
• Renal impairment: Dose reduction recommended; clearance reduced by approximately 30% in moderate impairment and 50% in severe impairment 1
• Hepatic impairment: Dose reduction recommended; clearance decreased by approximately 30% 1

Treatment Duration

Acute Phase

• Full therapeutic trial requires 4-8 weeks 2
• Assess response beginning within 1-2 weeks of starting therapy 2
• Modify treatment if inadequate response within 6-8 weeks 2

Continuation/Maintenance Phase

• Continue treatment for 4-9 months after satisfactory response for first episode 2, 1
• Longer treatment duration beneficial for patients with 2+ episodes 2
• Efficacy maintained for up to 40 weeks following 8-12 weeks of initial treatment 1
• After 9 months, consider dosage reduction to reassess need for medication 2

Clinical Benefits and Considerations

Advantages

• Potent and well-tolerated 2
• Promotes sleep, appetite, and weight gain - beneficial for patients with insomnia and poor appetite 2
• May have faster onset of action than SSRIs 3
• Low potential for drug interactions with medications metabolized by CYP2D6 4

Common Side Effects

• Sedation (most common) - typically more pronounced at lower doses 5
• Increased appetite and weight gain 2, 6
• Dry mouth 6

Important Precautions

• Discontinuation should be gradual (over 10-14 days) to limit withdrawal symptoms 2, 1
• Monitor for agranulocytosis and neutropenia (rare but serious) 6
• Avoid concomitant use with MAOIs - allow 14 days between stopping one and starting the other 1

Monitoring Recommendations

• Assess patient status, therapeutic response, and adverse effects regularly beginning within 1-2 weeks of starting therapy 2
• Periodically reassess need for maintenance treatment 1
• Monitor liver enzymes and complete blood count in patients with symptoms suggesting hematological abnormalities 6

Clinical Pearls

• Mirtazapine has a unique mechanism as a noradrenergic and specific serotonergic antidepressant (NaSSA) 3
• Particularly useful for patients with depression accompanied by anxiety, insomnia, or poor appetite 4
• Has minimal cardiovascular and anticholinergic effects 5
• Unlike SSRIs, mirtazapine has low incidence of sexual dysfunction and gastrointestinal side effects 5

Remember that while the recommended dosing range is 15-45 mg/day, the optimal dose should be determined based on clinical response and tolerability, with careful attention to potential side effects.