Mirtazapin Sandoz (Mirtazapine)

Mirtazapine is a NaSSA antidepressant that acts on noradrenergic and serotonergic pathways to treat a range of depressive disorders and associated symptoms.

• Major depressive disorder: reduces depressive symptoms and improves mood in adult patients.
• Depressive episodes in bipolar I disorder: used as adjunct therapy to manage depressive phases.
• Depression with insomnia: alleviates depressive symptoms while promoting sleep continuity.
• Treatment‑resistant depression: provides an alternative mechanism when other antidepressants have failed.
• Anxiety symptoms in depression: helps alleviate co‑existing anxiety while treating depressive mood.

• Mirtazapine exerts its antidepressant effect primarily by antagonizing central presynaptic α2‑adrenergic receptors, which increases the release of norepinephrine and serotonin. It also blocks postsynaptic 5‑HT2 and 5‑HT3 receptors, enhancing serotonergic transmission while reducing associated side effects, and antagonizes H1 histamine receptors, contributing to its sedative properties. These combined actions modulate neurotransmitter balance in brain regions involved in mood regulation.

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

Common Side Effects

• Sedation: drowsiness or feeling unusually sleepy.
• Increased appetite: heightened desire for food, especially carbohydrates.
• Weight gain: gradual increase in body weight during treatment.
• Dry mouth: reduced salivation leading to oral discomfort.
• Constipation: infrequent bowel movements or difficulty passing stool.
• Dizziness: sensation of light‑headedness or unsteadiness.

Serious or Rare Side Effects

• Agranulocytosis: severe reduction in white blood cells requiring immediate medical attention.
• Seizures: occurrence of convulsive episodes, particularly in predisposed individuals.
• Severe allergic reactions: rash, swelling, or anaphylaxis needing urgent care.
• Hepatotoxicity: liver enzyme elevations or liver injury.
• Suicidal thoughts: emergence or worsening of suicidal ideation.

When prescribing mirtazapine, clinicians should consider several safety precautions to minimize risks.

• Assess hepatic function: evaluate liver enzymes and adjust use in severe impairment.
• Monitor for worsening depression or suicidal ideation: observe patients closely during early treatment.
• Use caution in cardiovascular disease: may cause orthostatic hypotension or affect heart rate.
• Avoid abrupt discontinuation: taper the dose to reduce withdrawal symptoms.
• Pregnancy and lactation: risks are unclear; prescribe only if benefits outweigh potential harm.
• Store at ambient temperature: keep in original container, protect from moisture and light.

Mirtazapine can interact with other medicines, altering its effectiveness or increasing adverse effects.

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): concurrent use can precipitate serotonin syndrome.
• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): may raise mirtazapine plasma concentrations.
• Central nervous system depressants (e.g., alcohol, benzodiazepines): additive sedation and respiratory depression risk.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., carbamazepine, phenytoin): may reduce mirtazapine levels and efficacy.
• Anticholinergic agents: combined use can increase anticholinergic burden.
• Warfarin: mirtazapine may affect INR, requiring closer coagulation monitoring.