From the Guidelines
Mirtazapine is a viable treatment option for depression, with a faster onset of action compared to other second-generation antidepressants.
Key Points
- Mirtazapine has a faster onset of action compared to other second-generation antidepressants, such as citalopram, fluoxetine, paroxetine, or sertraline 1.
- The initial dosage of mirtazapine is typically 7.5 mg at bedtime, with a maximum dosage of 30 mg at bedtime 1.
- Mirtazapine is known to promote sleep, appetite, and weight gain, making it a useful option for patients with accompanying symptoms such as insomnia or anxiety 1.
- However, 38% of patients may not achieve a treatment response during 6 to 12 weeks of treatment with second-generation antidepressants, including mirtazapine, and 54% may not achieve remission 1.
- Mirtazapine can also be used as a sedating low-dose antidepressant for patients with comorbid depression and insomnia, although evidence for its efficacy in this context is relatively weak 1.
- The choice of mirtazapine should be based on the patient's response to the first treatment, as well as factors such as treatment history, coexisting conditions, and specific side effect profile 1.
From the FDA Drug Label
The mechanism of action of mirtazapine for the treatment of major depressive disorder, is unclear. However, its efficacy could be mediated through its activity as an antagonist at central presynaptic α2-adrenergic inhibitory auto-receptors and heteroreceptors and enhancing central noradrenergic and serotonergic activity. Mirtazapine acts as an antagonist at α2-adrenergic inhibitory auto-receptors and heteroreceptors and as an antagonist at serotonin 5-HT2 and 5-HT3 receptors.
Mirtazapine's mechanism of action is not fully understood, but it is believed to involve the antagonism of α2-adrenergic receptors and the enhancement of central noradrenergic and serotonergic activity. The drug also acts as an antagonist at serotonin 5-HT2 and 5-HT3 receptors. Mirtazapine is indicated for the treatment of major depressive disorder (MDD) in adults 2, 2.
- Key points:
- Mechanism of action is unclear
- Antagonism of α2-adrenergic receptors
- Enhancement of central noradrenergic and serotonergic activity
- Indicated for major depressive disorder (MDD) in adults
From the Research
Overview of Mirtazapine
- Mirtazapine is a tetracyclic antidepressant with a novel mechanism of action, increasing noradrenergic and serotonergic neurotransmission via blockade of central α2-adrenergic auto- and heteroreceptors 3.
- It has been shown to be effective in the treatment of major depression, with clinical improvements significantly superior to those of placebo and similar to those of tricyclic antidepressants (TCAs) 3, 4, 5.
- Mirtazapine has a unique pharmacokinetic profile, with a bioavailability of approximately 50% and an elimination half-life of 20-40 hours, allowing for once-daily administration 3, 4.
Efficacy and Comparisons
- Mirtazapine has been compared to other antidepressants, including tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), and serotonin-noradrenaline reuptake inhibitors (SNRIs) 6, 7.
- Studies have shown that mirtazapine is significantly more effective than SSRIs at two weeks and at the end of acute-phase treatment 7.
- Mirtazapine has also been shown to be more effective than venlafaxine, an SNRI, at two weeks and at the end of acute-phase treatment 7.
Safety and Tolerability
- Mirtazapine has been shown to be well-tolerated, with a lower incidence of anticholinergic, adrenergic, and serotonergic-related adverse events compared to TCAs 3, 4, 5.
- Common adverse effects associated with mirtazapine include somnolence, increased appetite, weight gain, and dizziness 3, 4, 5.
- Mirtazapine has a low potential for inducing seizures and is considered safe in overdose 3, 4.