What is the recommended dosing for mirtazapine (Remeron) for anxiety?

Mirtazapine Dosing for Anxiety

For anxiety treatment, mirtazapine should be started at 7.5 mg at bedtime with dosage increases made in 7.5-mg increments up to a maximum of 30 mg at bedtime based on clinical response and tolerability. 1

Dosing Protocol

Initial Dosing

• Start with 7.5 mg once daily at bedtime
• This low starting dose helps minimize initial side effects while providing anxiolytic benefits

Dose Titration

• Increase by 7.5 mg increments based on clinical response and side effects
• Allow 1-2 weeks between dose adjustments to assess efficacy and tolerability
• Target dose range: 15-30 mg daily at bedtime

Maximum Dose

• Maximum recommended dose for anxiety: 30 mg daily 1
• Higher doses (up to 45 mg) may be used in specific cases but offer limited additional benefit while potentially increasing side effects

Pharmacological Considerations

Mirtazapine works through a unique mechanism that contributes to its anxiolytic effects:

• Antagonist of presynaptic alpha-2 adrenergic receptors (increases norepinephrine and serotonin release)
• Potent antagonist of postsynaptic 5-HT2 and 5-HT3 receptors (reduces anxiety and GI side effects)
• Histamine H1 receptor antagonism (provides sedative effects beneficial for anxiety with insomnia) 2

Clinical Response Timeline

• Anxiolytic and sleep-improving effects may begin within the first week of treatment 2, 3
• Full anxiolytic effects typically develop within 2-4 weeks 2
• Sedative effects are more pronounced at lower doses (7.5-15 mg) and may decrease at higher doses 3

Advantages for Anxiety Treatment

• Rapid onset of anxiolytic action compared to SSRIs 3
• Beneficial effects on sleep disturbances commonly associated with anxiety 1, 3
• No sexual dysfunction (unlike many other antidepressants used for anxiety) 3
• Once-daily dosing due to 20-40 hour half-life 2

Side Effect Management

• Most common side effects: somnolence, increased appetite, weight gain, and dizziness 4
• Sedation is typically more pronounced at lower doses (7.5-15 mg) and may actually decrease at higher doses 3
• Taking the medication 1-2 hours before bedtime can help utilize the sedative effects for sleep while minimizing daytime drowsiness
• Weight gain monitoring is recommended, particularly with longer-term use

Special Considerations

• Elderly patients: Start at 7.5 mg and titrate more slowly
• Hepatic/renal impairment: Lower doses may be needed as mirtazapine is extensively metabolized by the liver and excreted in urine 5
• Avoid abrupt discontinuation; taper gradually over 10-14 days when stopping treatment
• May be particularly effective for patients with anxiety and comorbid insomnia or appetite/weight loss 1

Common Pitfalls to Avoid

1. Starting at too high a dose, which may lead to excessive sedation and early discontinuation
2. Titrating doses too quickly before allowing adequate time for side effect adaptation
3. Discontinuing treatment prematurely before anxiolytic effects fully develop (2-4 weeks)
4. Failing to recognize that sedation often decreases at higher doses
5. Not utilizing the sedative properties strategically by timing administration appropriately

Mirtazapine has demonstrated efficacy for anxiety disorders including post-traumatic stress disorder, panic disorder, and social anxiety disorder, though more large-scale studies are needed to fully establish its efficacy across all anxiety subtypes 6.