Noradrenergic and specific serotonergic antidepressant (NaSSA)
Antagonist at central presynaptic alpha-2-adrenergic autoreceptors and heteroreceptors, enhancing norepinephrine and serotonin release; antagonizes 5-HT2 and 5-HT3 receptors and potent H1 histamine receptor antagonist contributing to sedation.
Major depressive disorder (MDD)
Generalized anxiety disorder (GAD), posttraumatic stress disorder (PTSD), panic disorder, insomnia, chronic tension headache prophylaxis, post-stroke depression (PSD), depression in dementia
Oral tablets (7.5 mg, 15 mg, 30 mg, 45 mg)
7.5–15 mg p.o. nightly, titrating as clinically appropriate
15–45 mg/day
Half-life ~20–40 hours; metabolized via CYP1A2, CYP2D6, and CYP3A4; steady state in ~1 week
Sedation, increased appetite, weight gain, dry mouth, dizziness, constipation, elevated cholesterol and triglycerides
Agranulocytosis (rare), serotonin syndrome
Monitor weight, metabolic parameters (lipids, glucose), sedation level, and mood symptoms
Increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults with MDD and other psychiatric disorders
Mirtazapine should be used cautiously in elderly patients due to increased risks of sedation, falls, and weight gain. Limited evidence supports its use in neurodegenerative disorders such as Parkinson’s disease (PD) or dementia, though it may help with insomnia and weight loss in some patients. Regular monitoring for metabolic effects is recommended in patients with metabolic risk factors.