What are the typical doses and uses of Remeron (mirtazapine) for major depressive disorder?

Remeron (Mirtazapine) Dosing and Uses for Major Depressive Disorder

Mirtazapine (Remeron) is primarily used for major depressive disorder with a recommended starting dose of 15 mg once daily at bedtime, which can be increased up to 45 mg per day based on response. 1

Dosing Guidelines

• Initial dose: 15 mg once daily, preferably in the evening before sleep 1
• Titration: Dose increases should not be made in intervals of less than 1-2 weeks to allow sufficient time for evaluation of response 1
• Maximum dose: 45 mg per day 1
• Duration: After satisfactory response, treatment should continue for 4-9 months for first episode of depression; longer duration may be beneficial for patients with 2 or more episodes 2

Primary Uses

• Treatment of major depressive disorder (FDA-approved indication) 1
• Particularly effective for patients with depression accompanied by:
  • Sleep disturbances (promotes sleep) 2
  • Poor appetite (promotes appetite and weight gain) 2
  • Anxiety symptoms 2, 3

Mechanism of Action

• Noradrenergic and specific serotonergic antidepressant (NaSSA) 4
• Blocks central α2-adrenergic auto- and heteroreceptors, increasing noradrenergic and serotonergic neurotransmission 5
• Blocks 5-HT2 and 5-HT3 receptors, which helps avoid common serotonergic side effects 3
• Has histamine H1 receptor antagonist properties (contributing to sedation) 6

Efficacy

• Clinical trials demonstrated mirtazapine to be superior to placebo in treating major depression 1
• Comparable efficacy to tricyclic antidepressants and possibly faster onset of action than SSRIs 4, 7
• Therapeutic effects on depression typically begin within 2-4 weeks, though sleep and anxiety improvements may occur within the first week 5, 3
• Effective for both outpatient and hospitalized patients with depression 7

Special Considerations

• Screening requirement: Screen for bipolar disorder before initiating treatment 1
• Drug interactions:
  • Must wait at least 14 days between MAOIs and mirtazapine 1
  • Dose adjustments needed with strong CYP3A inducers or inhibitors 1
  • Dose adjustment may be needed with cimetidine 1
• Discontinuation: Gradually reduce dosage rather than stopping abruptly to limit withdrawal symptoms 1

Side Effects and Tolerability

• Most common side effects:
  • Somnolence/sedation (most frequent, may be less prominent at higher doses) 3
  • Increased appetite and weight gain 2, 3
  • Dry mouth 5
• Notable benefits compared to other antidepressants:
  • Minimal cardiovascular effects 5
  • Minimal anticholinergic effects 5, 3
  • Low risk of sexual dysfunction 3
  • Generally well-tolerated in elderly patients 7

Off-Label Uses

• Insomnia (particularly at lower doses of 7.5-15 mg) 2
• Anxiety disorders (preliminary evidence) 4
• Adjunctive therapy for other psychiatric conditions 4

Common Pitfalls and Caveats

• Weight gain can be significant and should be monitored, especially in patients concerned about weight 2
• Sedation may be problematic for some patients but beneficial for those with insomnia 2
• In rare cases, mirtazapine has been associated with agranulocytosis and neutropenia 7
• Transient elevations in liver enzymes and cholesterol levels may occur 6
• May not be ideal for patients who need activation rather than sedation 2

Mirtazapine offers a unique pharmacological profile that makes it particularly useful for patients with depression accompanied by sleep disturbances, anxiety, or appetite/weight loss, with a favorable side effect profile compared to many other antidepressants.