From the Guidelines
Mirtazapine is an antidepressant medication primarily used to treat major depressive disorder, belonging to the class of tetracyclic antidepressants, and is known for its sedating effects, making it helpful for patients with depression and insomnia. It works by increasing the levels of norepinephrine and serotonin in the brain, which helps improve mood 1. Mirtazapine is typically taken once daily at bedtime, with starting doses usually at 15 mg and potentially increasing to 30-45 mg based on response and tolerability. The medication is particularly helpful for patients with depression who also experience insomnia or appetite loss, as evidenced by its use in lower than antidepressant therapeutic dosages for the treatment of insomnia 1. Common side effects include drowsiness, increased appetite, weight gain, and dry mouth. These sedating effects tend to be more pronounced at lower doses (15 mg) and may actually decrease at higher doses. Patients should be aware that mirtazapine may take 2-4 weeks to show full therapeutic effects, and the medication should not be stopped abruptly but rather tapered under medical supervision. It should be used cautiously in elderly patients and those with liver or kidney problems, as dosage adjustments may be necessary. Key points to consider when prescribing mirtazapine include:
- Starting dose: 15 mg once daily at bedtime
- Potential increase to 30-45 mg based on response and tolerability
- Sedating effects, making it helpful for patients with insomnia
- Common side effects: drowsiness, increased appetite, weight gain, and dry mouth
- Caution in elderly patients and those with liver or kidney problems
- Importance of tapering the medication under medical supervision when stopping treatment.
From the FDA Drug Label
Mirtazapine tablets contain mirtazapine. Mirtazapine has a tetracyclic chemical structure and belongs to the piperazino-azepine group of compounds. Mirtazapine is an antidepressant medication, specifically a tetracyclic compound belonging to the piperazino-azepine group of compounds.
- It is used for the treatment of major depressive disorder (MDD) in adults 2.
- The chemical structure of mirtazapine is characterized as a racemic mixture with the empirical formula of C17H19N3 2.
From the Research
What is Mirtazapine
- Mirtazapine is an antidepressant that blocks presynaptic alpha 2-adrenergic receptors and postsynaptic serotonin type 2 and type 3 receptors 3.
- It is a noradrenergic and specific serotonergic antidepressant (NaSSA) that enhances central noradrenergic and serotonin 5-HT1 receptor-mediated serotonergic neurotransmission 4.
- Mirtazapine has FDA-approved labeling for the treatment of depression and may also have beneficial anxiolytic and sedative effects 3.
Mechanism of Action
- Mirtazapine increases noradrenergic and serotonergic neurotransmission via blockade of central α2-adrenergic auto- and heteroreceptors 5.
- It stimulates serotonin 5-HT1 receptors by blocking 5-HT2 and 5-HT3 receptors, which is thought to be responsible for its antidepressant activity 5.
Efficacy and Tolerability
- Mirtazapine has been shown to be effective in the treatment of major depression, with a rapid onset of action and sustained improvements in depressive symptoms 6, 7.
- It is generally well tolerated, with a lower incidence of anticholinergic, adrenergic, and serotonergic-related adverse events compared to tricyclic antidepressants 4, 5.
- Common adverse effects associated with mirtazapine include somnolence, increased appetite, weight gain, and dizziness 3.