What is the recommended dose of mirtazapine (Remeron) for treating decreased appetite?

Mirtazapine Dosing for Appetite Stimulation

The recommended starting dose of mirtazapine for appetite stimulation is 15 mg once daily at bedtime, with potential titration up to 45 mg daily based on response and tolerability. 1

Evidence-Based Dosing Recommendations

Mirtazapine has appetite-stimulating properties as a side effect that can be beneficial in patients with decreased appetite. According to clinical practice guidelines:

• Starting dose: 15 mg once daily at bedtime
• Titration: According to response and tolerability
• Maximum dose: Up to 45 mg once daily 1

This dosing recommendation is supported by the American Gastroenterological Association (AGA) clinical practice guidelines, which specifically list mirtazapine's common side effects as including "increased appetite and weight gain" 1.

Mechanism for Appetite Stimulation

Mirtazapine increases appetite through several mechanisms:

• Antagonism of serotonin 5-HT2 and 5-HT3 receptors 2
• Histamine H1 receptor blockade, which is associated with increased appetite 2
• Enhancement of noradrenergic neurotransmission 3

Clinical Considerations

Efficacy for Appetite

• Mirtazapine has demonstrated increased appetite as a side effect in multiple studies
• In placebo-controlled trials, increased appetite (11% vs 2%) and weight gain (10% vs 1%) occurred significantly more frequently with mirtazapine than placebo 2
• Even low doses (7.5 mg) have shown improvement in appetite in cancer patients receiving chemotherapy 4

Special Populations

• Elderly patients: The European Society for Clinical Nutrition and Metabolism (ESPEN) recommends against using mirtazapine solely for appetite stimulation in elderly patients without depression, as potential risks may outweigh uncertain benefits 5
• Cancer patients: Low-dose mirtazapine (7.5 mg) has shown efficacy for improving appetite in cancer patients receiving chemotherapy 4
• Patients with depression and poor appetite: Mirtazapine may be particularly appropriate when both conditions coexist 5

Dosing Pearls

• Lower doses (7.5-15 mg) may be sufficient for appetite stimulation and may cause less sedation than higher doses 4
• Once-daily bedtime dosing is appropriate due to mirtazapine's 20-40 hour half-life 6
• Sedation tends to be more pronounced at lower doses (15 mg) and may actually decrease at higher doses (30-45 mg) 3

Potential Adverse Effects

Common side effects to monitor:

• Sedation/somnolence (most common)
• Weight gain
• Dry mouth
• Dizziness
• Sleep disorders 1, 2

Monitoring

• Monitor weight gain to ensure appropriate response
• Assess for excessive sedation, especially at initiation
• In rare cases, monitor for hematological changes (agranulocytosis, neutropenia) 2

Contraindications and Cautions

• Use with caution in patients with hepatic or renal impairment
• Avoid concomitant use with MAOIs
• Use cautiously with other CNS depressants 2

Mirtazapine's appetite-stimulating effects make it a useful option for patients with decreased appetite, particularly when depression is also present, though it should be used with appropriate monitoring for side effects.