Mirtazapina Ciclum (Mirtazapine)

Mirtazapine is indicated for depressive disorders and is used within the antidepressant therapeutic pathway to improve mood and functional outcomes.

• Major depressive disorder: reduces depressive symptoms and improves overall mood in adult patients.
• Depressive episode in bipolar disorder: used as an adjunct to stabilize depressive phases when prescribed by a specialist.
• Depression with anxiety features: helps alleviate both low mood and associated anxiety, enhancing sleep quality.

• Mirtazapine acts as an antagonist at central presynaptic α2‑adrenergic receptors, which disinhibits norepinephrine release. It also blocks 5‑HT2 and 5‑HT3 serotonin receptors and the histamine H1 receptor, resulting in increased serotonergic and noradrenergic transmission while producing sedative effects. This combined activity enhances mood and sleep.

Mirtazapine may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Sedation or somnolence: feeling unusually sleepy or drowsy.
• Increased appetite and weight gain: notable rise in hunger and body weight.
• Dry mouth: reduced salivation leading to discomfort.
• Constipation: slowed gastrointestinal motility.
• Dizziness: sensation of light‑headedness, especially when standing.

Serious or Rare Side Effects

• Agranulocytosis or severe neutropenia: marked reduction in white blood cells.
• Seizures: risk of convulsive episodes, particularly in predisposed individuals.
• Hypersensitivity reactions: rash, swelling, or anaphylaxis.
• Suicidal ideation: emergence or worsening of suicidal thoughts.
• Hepatic dysfunction: abnormal liver enzyme elevations.

Before initiating therapy, clinicians should evaluate several safety considerations.

• Psychiatric assessment: monitor for worsening depression or emergence of suicidal thoughts.
• Hepatic function: assess liver status; dose adjustment may be needed in severe impairment.
• Cardiovascular status: watch for orthostatic hypotension, especially in patients with low blood pressure.
• Elderly patients: increased risk of sedation and falls; start at lower doses.
• Discontinuation: avoid abrupt stop; taper gradually under medical supervision.
• Store at ambient temperature: keep in the original container, protect from moisture and light.

Mirtazapine can interact with several drug classes, requiring careful management.

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): risk of serotonin syndrome.
• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): may increase mirtazapine plasma levels.
• Central nervous system depressants (e.g., benzodiazepines, alcohol): enhanced sedation.
• Other serotonergic agents (e.g., SSRIs, SNRIs, tramadol): heightened risk of serotonin syndrome.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., carbamazepine, phenytoin): may reduce efficacy.
• Anticholinergic drugs: additive anticholinergic burden.
• Warfarin: potential alteration of INR, requiring monitoring.