Mirtazapine (Remeron) Dosing Guidelines
The recommended starting dose of mirtazapine is 15 mg once daily, administered orally in the evening prior to sleep, with a maximum recommended dose of 45 mg per day. 1
Initial Dosing and Titration
- Start with 15 mg once daily, preferably in the evening before bedtime 1, 2
- If patients do not have an adequate response to the initial 15 mg dose, increase the dose up to a maximum of 45 mg per day 1
- Dose changes should not be made in intervals of less than 1-2 weeks to allow sufficient time for evaluation of response 1, 3
- For elderly patients or those with hepatic or renal impairment, careful dosage titration and close monitoring for adverse events is recommended 3
Clinical Effects and Timing
- Onset of clinical antidepressant effect typically occurs in 2-4 weeks, similar to other antidepressants 2
- Sleep disturbances and anxiety symptoms may improve within the first week of treatment 2, 4
- The drug's elimination half-life of 20-40 hours enables once-daily bedtime dosing 2, 4
Common Side Effects
- Sedation/somnolence (most common side effect, especially at lower doses) 2, 4
- Increased appetite and weight gain 2, 4
- Dry mouth 4
- Dizziness 5
Special Considerations
- Mirtazapine is particularly effective for patients with depression accompanied by sleep disturbances 6, 4
- The drug is potent and well-tolerated, promoting sleep, appetite, and weight gain 7
- Sedation tends to be more pronounced at lower doses (15 mg) and may decrease at higher doses 4
- Mirtazapine has minimal cardiovascular and anticholinergic effects 2
- The drug lacks many of the serotonergic side effects seen with SSRIs, such as gastrointestinal symptoms, insomnia, and sexual dysfunction 2
Discontinuation
- Gradually reduce the dosage rather than stopping abruptly to minimize discontinuation symptoms 1
- Adverse reactions may occur upon discontinuation or dose reduction 1
Drug Interactions
- At least 14 days must elapse between discontinuation of a monoamine oxidase inhibitor (MAOI) antidepressant and initiation of mirtazapine 1
- Dosage adjustments may be needed with concomitant use of strong CYP3A inducers or inhibitors 1
- Use caution when combining with other sedative medications 3
Mirtazapine's unique mechanism as a noradrenergic and specific serotonergic antidepressant (NaSSA) provides effective antidepressant action with a different side effect profile compared to other classes of antidepressants, making it particularly useful for patients with insomnia or appetite disturbances associated with depression 2, 8.