Mirtazapine Amarox (Mirtazapine)

Mirtazapine is indicated for major depressive disorder, acting on the serotonergic and noradrenergic pathways to improve mood and functional outcomes.

• Major depressive disorder: alleviates depressive symptoms and improves overall functioning.
• Persistent depressive disorder (dysthymia): helps reduce chronic low mood when other therapies are insufficient.
• Treatment‑resistant depression: may be added to augment response in patients who have not responded to first‑line agents.

• Mirtazapine blocks central presynaptic α2‑adrenergic receptors, which increases the release of norepinephrine and serotonin. It also antagonizes postsynaptic 5‑HT2 and 5‑HT3 receptors and histamine H1 receptors, contributing to its antidepressant and sedative properties without directly stimulating serotonin reuptake.

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

Common Side Effects

• Sedation or drowsiness
• Increased appetite and weight gain
• Dry mouth
• Constipation
• Dizziness
• Peripheral edema

Serious or Rare Side Effects

• Agranulocytosis or severe neutropenia
• Hepatic dysfunction or jaundice
• Severe hypersensitivity reactions (e.g., Stevens‑Johnson syndrome)
• Suicidal thoughts or behavior, especially early in treatment
• Seizures
• Cardiac arrhythmias (QT prolongation)

Before initiating therapy, clinicians should evaluate patient‑specific risk factors and monitor for emerging issues.

• Hepatic function: assess liver enzymes in patients with known hepatic disease.
• Weight monitoring: track body weight regularly due to potential weight gain.
• Discontinuation: taper gradually to avoid withdrawal symptoms.
• Elderly patients: start at lower doses and monitor for excessive sedation.
• Concomitant CNS depressants: use caution when combined with alcohol or other sedatives.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): risk of hypertensive crisis; a washout period is required.
• CNS depressants (e.g., benzodiazepines, opioids): may potentiate sedation and respiratory depression.

Moderate Interactions (Monitor Closely)

• CYP1A2 inhibitors (e.g., fluvoxamine): may increase mirtazapine plasma levels.
• CYP2D6 substrates (e.g., codeine): altered metabolism may affect efficacy.
• Anticholinergic agents: additive dry mouth and constipation.
• Anticoagulants (e.g., warfarin): monitor INR for potential changes.