Mirtazapine Dosing for Appetite Stimulation
For appetite stimulation, mirtazapine is typically prescribed at a dose of 15 mg once daily at bedtime, which is often sufficient to achieve the desired effect while minimizing sedation. Higher doses may not provide additional appetite stimulation benefits but can increase sedation.
Dosing Protocol
Initial Dosing
- Start with 15 mg once daily, taken in the evening before sleep
- This lower dose is often effective for appetite stimulation while minimizing side effects
- The sedating effects are most pronounced at this lower dose, which can be beneficial for patients with sleep disturbances
Dose Adjustments
- If inadequate response after 1-2 weeks, consider increasing to 30 mg once daily
- Monitor closely for increased sedation when titrating from 15 mg to 30 mg 1
- Maximum dose for appetite stimulation typically does not exceed 30 mg daily
- Higher doses (45 mg) may actually have less sedating and appetite-stimulating effects due to different receptor activity profiles
Mechanism of Action for Appetite Stimulation
Mirtazapine stimulates appetite through:
- Potent antagonism of histamine H1 receptors 2
- Blockade of serotonin 5-HT2 and 5-HT3 receptors 3
- These effects are most pronounced at lower doses (15-30 mg)
Clinical Evidence and Outcomes
- In studies of hospitalized patients, mirtazapine has shown numerical improvements in meal intake 4
- In Alzheimer's patients, mirtazapine 30 mg daily led to weight gain in 77.3% of patients after 3 months (mean gain of 1.93 kg or 3.9% of initial body weight) 5
- Appetite stimulation effects may begin within the first week of treatment 2
Monitoring and Follow-up
- Evaluate therapeutic response after 4-8 weeks 1
- Monitor weight regularly as increased appetite is a common side effect 1
- Approximately 10% of patients experience weight gain 1
Important Considerations and Precautions
- Sedation is dose-dependent and most common during initial titration 1
- Once-daily bedtime dosing is recommended due to the 20-40 hour elimination half-life 2
- Mirtazapine has minimal cardiovascular and anticholinergic effects 2
- Unlike many other antidepressants, mirtazapine has minimal sexual dysfunction side effects 2
- Mirtazapine has been successfully used for non-mechanical vomiting after gastric bypass surgery at doses of 30 mg daily 6
Pitfalls to Avoid
- Avoid rapid dose escalation, which can lead to excessive sedation
- Avoid morning dosing due to potential daytime sedation
- Be aware that weight gain may be excessive in some patients and should be monitored
- Rare but serious side effects include agranulocytosis and neutropenia 3
- Excessive sedation may occur with concomitant use of other CNS depressants or alcohol 3
For most patients requiring appetite stimulation, the 15 mg dose provides the optimal balance between efficacy and tolerability, with the option to increase to 30 mg if needed for additional effect.