Class: Antidepressant, Alpha-2 Antagonist
Dosage Forms. Tablet: 7.5 mg, 15 mg, 30 mg, 45 mg; Tablet (Disintegrating): 15 mg, 30 mg, 45 mg
Common FDA Label Indication, Dosing, and Titration.
1. Depression: 15 mg po daily hs; may titrate to 45 mg po daily hs
Off-Label Uses. None
MOA. Mirtazapine is an antidepressant that antagonizes presynaptic α2-adrenergic auto- and hetero-receptors that are responsible for controlling the release of norepinephrine and serotonin (5-HT). It is also a potent antagonist of postsynaptic 5-HT2 and 5-HT3 receptors. The net outcome of these effects is increased noradrenergic activity and enhanced 5-HT activity, especially at 5-HT1A receptors. This unique mechanism of action preserves antidepressant efficacy but minimizes many of the adverse effects common to heterocyclic antidepressants and SSRIs.
Drug Characteristics: Mirtazapine
Medication Safety Issues: Mirtazapine
Drug Interactions: Mirtazapine
Adverse Reactions: Mirtazapine
Efficacy Monitoring Parameters. Improvement in symptoms of depression (suicidal thoughts or intent, change in appetite, lack of energy, change in sleep patterns, etc).
Toxicity Monitoring Parameters. Worsening of depression, suicidality, or unusual changes in behavior, especially at the initiation of therapy or with dosage increases or decreases; monitor CBC, lipid panel, body weight, and LFTs.
Key Patient Counseling Points. Orally disintegrating tablet blister pack should be opened with dry hands and placed on tongue; no water is needed; tablet should be used immediately after removal from package; once removed, it cannot be stored. Avoid activities requiring mental alertness until drug effects are realized. Report worsening depression, suicidal ideation, or unusual changes in behavior. Do not drink alcohol while taking this drug.
Clinical Pearls. Safety and effectiveness in pediatric patients have not been established. Use with caution in elderly patients who may be more susceptible to adverse effects. Medication guide required at dispensing.