From the Guidelines
The maximum recommended dose of mirtazapine is 45 mg per day, typically taken as a single dose at bedtime. This is based on the most recent and highest quality study available, which suggests that mirtazapine can be titrated up to a maximum of 45 mg once daily, according to response to treatment and tolerability 1. Treatment usually starts at a lower dose of 15 mg daily, which can be gradually increased every 1-2 weeks based on clinical response and tolerability. While some patients achieve adequate symptom relief at 15-30 mg, others may require the full 45 mg dose for optimal antidepressant effect.
Some key points to consider when prescribing mirtazapine include:
- Starting dose: 15 mg once daily
- Dose titration: according to response to treatment and tolerability, up to a maximum of 45 mg once daily
- Common side effects: sleep disorders, constipation or diarrhea, anxiety, increased appetite and weight gain, nausea, headache, fatigue
- It's essential to monitor patients for side effects and therapeutic response, especially when adjusting the dose.
It's worth noting that higher doses of mirtazapine don't necessarily provide better sedation, as the medication's noradrenergic effects become more prominent at higher doses, which can actually reduce sedation 1. Mirtazapine should be taken consistently at the same time each day, and any dose adjustments should be made under medical supervision. The study from 2021 provides the most up-to-date guidance on the use of mirtazapine, and its recommendations should be followed in clinical practice 1.
From the FDA Drug Label
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 The maximum dose of mirtazapine is 45 mg per day 2.
From the Research
Mirtazapine Dosage
- The recommended starting dosage of mirtazapine is 15 mg/day for 4 days, then 30 mg/day for 10 days 3.
- If effective, the drug should be continued unchanged at this dosage or, in patients assessed as insufficiently improved, the daily dosage may be further increased to 45 mg/day 3.
- The maximum allowed dose was 45 mg per day in a 17-week naturalistic study in Lithuania 4.
Dosage Titration
- In patients with hepatic or renal insufficiency, careful dosage titration as well as regular and close monitoring for adverse events is recommended 3.
- The mean daily dose of mirtazapine orally disintegrating tablets was 29.0 (3.8) mg in a 17-week naturalistic study in Lithuania 4.
Efficacy and Tolerability
- Mirtazapine is an effective antidepressant for the treatment of major depression and also has the potential to be of use in other psychiatric indications 5.
- Mirtazapine is generally well tolerated in patients with depression, with the most common adverse events being weight gain, sedation, dizziness, and dry mouth 4, 5.