Is mirtazapine (Remeron) 7.5mg effective for appetite stimulation?

Mirtazapine 7.5mg for Appetite Stimulation

Mirtazapine 7.5mg is suboptimal for appetite stimulation; the recommended starting dose is 15mg nightly, which demonstrates clinically meaningful appetite-stimulating effects. 1, 2

Evidence-Based Dosing for Appetite Stimulation

The appetite-stimulating effect of mirtazapine is dose-dependent and well-established at therapeutic doses:

• The FDA-approved starting dose is 15mg once daily at bedtime, with an effective therapeutic range of 15-45mg daily 2, 3, 4
• At 15mg daily, mirtazapine produces significant appetite stimulation, with 17% of patients reporting increased appetite compared to 2% with placebo 2
• Weight gain of ≥7% body weight occurred in 7.5% of patients at therapeutic doses (15-45mg) versus 0% with placebo 2
• At 30mg daily, a retrospective study in dementia patients showed mean weight gain of 1.9kg at 3 months and 2.1kg at 6 months, with approximately 80% experiencing weight gain 1

Why 7.5mg is Inadequate

The 7.5mg dose falls below the established therapeutic threshold and lacks evidence for clinically meaningful appetite stimulation:

• No clinical trials have evaluated 7.5mg for appetite stimulation 1, 2, 3
• The pharmacological mechanisms responsible for appetite stimulation (H1 receptor blockade and 5-HT3 antagonism) require therapeutic dosing to achieve clinical effect 1, 5
• Starting below 15mg risks inadequate response and delays clinical benefit 3, 4

Pharmacological Mechanism

Mirtazapine stimulates appetite primarily through histamine H1 receptor blockade, which is the most significant contributor to weight gain 1:

• 5-HT3 receptor antagonism reduces nausea and early satiety, indirectly promoting food intake 1, 5
• These effects are most pronounced at doses ≥15mg daily 2, 3

Clinical Algorithm for Use

When appetite stimulation is the primary goal:

1. If depression is present: Start mirtazapine 15mg nightly; this provides dual benefit of treating depression while addressing appetite loss 1
2. If depression is absent: Mirtazapine is not recommended as a standalone appetite stimulant, particularly in dementia patients without depression 1
3. Monitor weekly initially for appetite improvement and weight gain 1
4. Consider dose escalation to 30mg after 2-4 weeks if inadequate response at 15mg 1, 3

Specific Clinical Scenarios Where Evidence Supports Use

• Depression with appetite loss and weight loss: Mirtazapine is specifically indicated, offering therapeutic advantage over SSRIs (which are weight-neutral to weight-loss promoting) and bupropion (which causes weight loss) 1
• Refractory gastroparesis: Improved nausea, vomiting, and weight loss through 5-HT3 antagonism 1
• Functional dyspepsia with early satiety: Demonstrated improvement in weight loss and dyspeptic symptoms 1
• Palliative care settings: Used to stimulate appetite in end-stage disease when depression coexists 6, 1

Critical Precautions

Exercise caution or avoid mirtazapine when weight gain would be detrimental 1:

• Obesity or metabolic syndrome
• Cardiovascular disease where weight gain poses risk 1
• Patients without depression (risk-benefit ratio unfavorable) 1

Common adverse effects at therapeutic doses include 2, 3:

• Somnolence (54% vs 18% placebo) - may improve with continued use
• Dry mouth (25% vs 16% placebo)
• Sedation (19% vs 5% placebo)

Practical Implementation

Start with 15mg at bedtime, not 7.5mg 1, 2, 3:

• Take at bedtime to leverage sedative effects
• Assess response after 1-2 weeks for appetite and sleep improvement 4, 5
• If inadequate appetite stimulation after 2-4 weeks, increase to 30mg nightly 1, 3
• Maximum dose for appetite stimulation is typically 30-45mg daily 2, 3

The 7.5mg dose lacks evidence and should not be used when appetite stimulation is the therapeutic goal.