TaperCommunitymirtazapine
Boxed Warning
Suicidality risk in children, adolescents, and young adults under 25 during initial treatment.
Mirtazapine is a noradrenergic and specific serotonergic antidepressant (NaSSA) approved for major depressive disorder. It has a unique mechanism that does not involve reuptake inhibition. It is known for sedation and appetite stimulation, especially at lower doses.
7.5mg, 15mg, 30mg, 45mg
Tablets: 7.5mg, 15mg, 30mg, 45mg; Orally disintegrating tablets (SolTab): 15mg, 30mg, 45mg
Category C (risk cannot be ruled out)
Antagonist at central alpha-2 adrenergic autoreceptors and heteroreceptors, increasing noradrenergic and serotonergic neurotransmission. Also antagonizes 5-HT2A, 5-HT2C, 5-HT3, and histamine H1 receptors. The strong H1 antagonism causes sedation and weight gain.
Rebound insomnia is very common at lower doses due to stronger antihistamine effect. Paradoxically more sedating at lower doses.
Tablet can be split or dissolved in water for precise dosing. Rebound insomnia at lower doses often mistaken for relapse — distinguish withdrawal from relapse by timing.
Toxicity
Relatively low toxicity in overdose compared to TCAs. Agranulocytosis/neutropenia rarely reported. Weight gain and metabolic effects. Serotonin syndrome possible with serotonergic combinations.
Pharmacokinetics
Rapidly and completely absorbed. Bioavailability ~50%. Tmax ~2 hours. Food has minimal effect on absorption.
~4.5 L/kg
Extensively metabolized hepatically via CYP2D6, CYP3A4, and CYP1A2 to demethyl and hydroxylated metabolites, which have minimal pharmacological activity.
Renal (~75%) and fecal (~15%). Less than 5% excreted unchanged in urine.
~85%
~230 mL/min (apparent oral clearance)
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