Mirtazapine Dosing for Appetite Stimulation
For appetite stimulation, start mirtazapine at 15 mg once daily, administered orally in the evening prior to sleep. 1, 2
Initial Dosing and Administration
- The FDA-approved starting dose of mirtazapine is 15 mg once daily, preferably taken in the evening before bedtime 1
- This dosage is effective for appetite stimulation while minimizing daytime sedation 3
- Low-dose mirtazapine (15 mg) is particularly effective for appetite stimulation while limiting side effects 2
- Some patients may respond to doses as low as 7.5 mg (half of a 15 mg tablet), especially elderly patients or those sensitive to sedation 4
Dose Titration
- If inadequate response after 1-2 weeks, the dose may be increased to 30 mg daily 1
- Maximum dose is 45 mg daily, though appetite stimulation effects are often achieved at lower doses 1
- Allow 1-2 weeks between dose adjustments to properly evaluate response 1
- Higher doses don't necessarily provide better appetite stimulation but may increase side effects 2
Monitoring Response
- Assess appetite improvement and meal intake within 1-2 weeks of initiation 5
- Monitor weight weekly to evaluate effectiveness 2
- Evaluate for side effects, particularly excessive sedation, which may limit daytime functioning 2, 6
- If no improvement in appetite is seen after 2-4 weeks of therapy at an adequate dose, consider alternative agents 2
Common Side Effects to Monitor
- Drowsiness/sedation (23% vs 14% with placebo) 6
- Dry mouth (25% vs 16% with placebo) 6
- Increased appetite (11% vs 2% with placebo) - this is the desired effect 6
- Weight gain (10% vs 1% with placebo) 6
- Dizziness 7
Important Considerations
- Mirtazapine has shown effectiveness for appetite stimulation in hospitalized patients with a mean improvement in meal intake of 17.12% 5
- The medication should not be discontinued abruptly, as this can lead to discontinuation syndrome including anxiousness, nausea, tremor, and loss of appetite 8
- If discontinuation is needed, gradually taper the dose rather than stopping abruptly 1, 8
- Mirtazapine can be particularly useful for patients with concomitant sleep difficulties or mood disorders 3
Precautions
- Screen for bipolar disorder before initiating treatment 1
- Allow at least 14 days between discontinuing MAOIs and starting mirtazapine 1
- Dose adjustments may be needed with strong CYP3A inducers or inhibitors 1
- Monitor for rare but serious hematological changes (e.g., agranulocytosis) 6
- Use with caution in patients with hepatic or renal insufficiency 6
Mirtazapine's unique mechanism as a noradrenergic and specific serotonergic antidepressant (NaSSA) makes it effective for appetite stimulation through its antagonism of central α2-adrenergic receptors and serotonin 5-HT2 and 5-HT3 receptors 6, 7. This pharmacological profile contributes to its effectiveness in improving appetite while also providing potential benefits for sleep and mood.