Remeron (Mirtazapine) Dose Titration
Mirtazapine should be increased every 5 to 7 days using increments of the initial dose until therapeutic benefits or significant side effects become apparent 1.
Standard Titration Schedule
Based on guideline recommendations and FDA labeling, the typical approach is:
- Starting dose: 7.5-15 mg at bedtime 1
- First increase: After 4 days, increase to 30 mg/day 2
- Subsequent increases: If insufficient improvement after 10 days at 30 mg, may increase to 45 mg/day 2
- Titration interval: Every 5-7 days as the general rule 1
Clinical Context for Dose Increases
When to Increase
The most recent guideline evidence suggests increasing by increments of the initial dose every 5 to 7 days until you observe either therapeutic benefits or dose-limiting side effects 1. This means if you started at 15 mg, you would increase by 15 mg increments.
Evidence for Early Non-Responders
Research specifically examining early non-responders found that patients who failed to show ≥20% improvement at week 1 on 15 mg benefited significantly from dose escalation to 30 mg (greater HDRS-17 score reduction, p=0.003), though increases beyond 30 mg to 45 mg showed no additional benefit 3.
Practical Dosing Algorithm
For typical patients:
- Days 1-4: 15 mg at bedtime
- Days 5-14: 30 mg at bedtime
- Day 15+: Consider 45 mg if inadequate response at 30 mg
For patients requiring slower titration (elderly, hepatic/renal impairment):
- Start at 7.5 mg
- Increase by 7.5 mg increments every 7 days
- Maximum 30 mg in elderly 1
Important Caveats
Dose-dependent considerations:
- Sedation is paradoxically more prominent at lower doses (15 mg) due to predominant H1 antagonism; higher doses (30-45 mg) increase noradrenergic activity which counteracts sedation 4, 5
- The 30 mg dose appears to be the "sweet spot" - increases beyond this may not provide additional efficacy 3
Special populations requiring dose adjustment:
- Obesity (BMI ≥28): Reduce dose by ~30% (use 22.5-30 mg/day instead of 30-37.5 mg/day) 6
- Co-administration with paroxetine: Reduce dose by ~27% (use 22.5-30 mg/day) 6
- Co-administration with fluvoxamine: Reduce dose by ~50% (use 15 mg/day) 6
- Hepatic impairment: Clearance reduced by 30% - use slower titration 2
- Renal impairment (GFR <40): Clearance reduced by 30-50% - use slower titration 2
Steady-state pharmacokinetics: Mirtazapine reaches steady state within 5 days, with a half-life of 20-40 hours 2. This supports the 5-7 day titration interval, as you need to wait for steady state before assessing response to each dose level.
The evidence strongly supports that faster is not better - rushing titration beyond every 5-7 days provides no advantage and may increase side effects, while waiting longer than necessary delays therapeutic benefit 1.