Mirtazapine Dose Escalation After 4 Days at 30 mg
It is too early to increase the dose—continue mirtazapine 30 mg at bedtime for at least 1-2 weeks before considering any dose adjustment. 1
Rationale for Waiting
The FDA-approved prescribing information explicitly states that dose changes should not be made in intervals of less than 1 to 2 weeks to allow sufficient time for evaluation of response to a given dose. 1 Your patient has only been on treatment for 4 days, which is insufficient time to assess therapeutic response.
Standard Dosing Algorithm
Starting dose: 15 mg once daily at bedtime 1, 2
Current dose: Your patient appears to have started at 30 mg (which is acceptable but higher than the typical starting dose) 1
Next dose if needed: 45 mg once daily (maximum recommended dose) 1, 2
Timeline for Dose Adjustment
- Minimum interval between dose changes: 1-2 weeks 1
- Time to assess full therapeutic response: 4-8 weeks 2
- Early symptom improvement: Sleep disturbances and anxiety may improve within the first week, but full antidepressant effect requires 2-4 weeks 3, 4
When to Consider Increasing to 45 mg
Increase the dose to 45 mg at bedtime only if:
- The patient has been on 30 mg for at least 1-2 weeks 1
- There is inadequate response to 30 mg after this trial period 1, 5
- The patient tolerates 30 mg without dose-limiting adverse effects 1
Important Clinical Considerations
Common adverse effects at current dose (30 mg): 5, 6, 4
- Drowsiness/sedation (occurs in approximately 19-23% of patients)
- Dry mouth (25%)
- Increased appetite (11%)
- Weight gain (10%)
Paradoxical sedation pattern: Sedation is actually more common at subtherapeutic doses (7.5-15 mg) and may decrease at therapeutic doses of 30-45 mg. 6 If your patient is experiencing excessive sedation at 30 mg, this may improve with time rather than requiring dose reduction.
Serious but rare adverse effects to monitor: 5, 6
- Agranulocytosis and neutropenia (very rare but potentially serious)
- Consider baseline and periodic CBC monitoring, especially in the first few months
Common Pitfall to Avoid
Do not increase the dose prematurely. The most common error is escalating too quickly before allowing adequate time to assess response. 1 Mirtazapine reaches steady-state concentrations after 4-6 days, but clinical antidepressant response requires 2-4 weeks. 7, 4