From the Guidelines
Mirtazapine has a significantly faster onset of action compared to other antidepressants, making it a valuable treatment option for patients who require rapid improvement of depressive symptoms. This is particularly important in clinical practice, as almost 38% of patients do not achieve a treatment response during 6 to 12 weeks of treatment with second-generation antidepressants, and 54% do not achieve remission 1. Mirtazapine's unique mechanism of action, which involves blocking alpha-2 adrenergic receptors and certain serotonin receptors, produces sedative effects at lower doses, making it beneficial for patients with depression accompanied by insomnia.
Key Benefits of Mirtazapine
- Rapid onset of action, often within the first week of treatment
- Improvement of sleep and appetite disturbances
- Fewer sexual side effects compared to SSRIs
- Less gastrointestinal distress compared to SSRIs
- Particularly beneficial for patients with depression accompanied by insomnia, decreased appetite, or significant weight loss
Considerations for Clinical Practice
- Mirtazapine is typically started at 15mg at bedtime, with potential increases to 30-45mg daily
- The medication's sedating properties tend to decrease at higher doses as its noradrenergic effects become more prominent
- Weight gain can be a notable side effect due to increased appetite and antihistamine properties
- Mirtazapine is especially valuable for depressed patients who cannot tolerate the sexual or gastrointestinal side effects of other antidepressants 1.
From the FDA Drug Label
The efficacy of mirtazapine tablets as a treatment for major depressive disorder was established in 4 placebo- controlled, 6-week trials in adult outpatients meeting DSM-III criteria for major depressive disorder. Superiority of mirtazapine tablets over placebo was also found for certain factors of the HDRS, including anxiety/somatization factor and sleep disturbance factor.
A significant advantage of mirtazapine (Remeron) over other antidepressants is its ability to address anxiety/somatization and sleep disturbance factors, in addition to its antidepressant effects, as demonstrated by its superiority over placebo in these areas 2.
- This makes it a potentially useful option for patients with major depressive disorder who also experience anxiety or sleep disturbances.
From the Research
Advantages of Mirtazapine
- Mirtazapine has a unique mechanism of action that refines the specificity of effects on noradrenergic and serotonergic systems, resulting in increased noradrenergic activity and specific increased serotonergic activity, especially at 5-HT1A receptors 3.
- It has minimal cardiovascular and anticholinergic effects, and essentially lacks serotonergic effects such as gastrointestinal symptoms, insomnia, and sexual dysfunction, making it a favorable option for patients who experience these side effects with other antidepressants 3, 4, 5, 6, 7.
- Mirtazapine has a rapid onset of action, with significant reductions in symptoms of depression, anxiety, and sleep disturbance noted as early as 1 week after starting treatment 4, 7.
- It is relatively safe in overdose, with no reports of significant cardiovascular or respiratory effects, and has a low propensity for inducing seizures 3, 5, 6.
- Mirtazapine is also associated with increased sedation, which can be beneficial for patients with insomnia, and has a low risk of agranulocytosis, a potentially serious side effect 4, 5, 6.
Comparison to Other Antidepressants
- Mirtazapine's efficacy is comparable to that of tricyclic antidepressants, such as amitriptyline, clomipramine, and doxepin, and selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, paroxetine, and citalopram 4, 5, 7.
- It has a more favorable side effect profile than tricyclic antidepressants, with fewer anticholinergic, adrenergic, and serotonergic-related adverse effects 4, 5.
- Mirtazapine is also a good option for patients who experience sexual side effects from other antidepressants, as it has no sexual side effects 6, 7.