Mirtazapin Krka (Mirtazapine)

Mirtazapine is used primarily in the treatment of depressive disorders, targeting mood regulation and associated symptoms.

• Major depressive disorder: reduces core depressive symptoms such as low mood, loss of interest, and improves overall functional outcomes.
• Depression with anxiety features: alleviates both depressive mood and concurrent anxiety symptoms, leading to better patient comfort and daily functioning.
• Insomnia associated with depression: promotes sleep onset and maintenance, helping restore normal sleep patterns and reduce fatigue.

• Mirtazapine acts as an antagonist at central presynaptic α2‑adrenergic receptors, increasing the release of norepinephrine and serotonin. It also blocks postsynaptic 5‑HT2 and 5‑HT3 receptors, enhancing serotonergic transmission while reducing related side effects, and antagonizes histamine H1 receptors, contributing to its sedative properties. Additionally, the drug’s antagonism at 5‑HT2C receptors may further increase dopaminergic activity in certain brain regions, supporting its antidepressant effect.

Mirtazapine may be associated with a range of adverse reactions, varying in frequency and severity.

Common Side Effects

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

Serious or Rare Side Effects

• Agranulocytosis (rare blood disorder)
• Severe hypersensitivity reactions (e.g., Stevens‑Johnson syndrome)
• Suicidal thoughts or behavior, especially early in treatment.

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

• Monitor hepatic function: assess liver enzymes before and during therapy in patients with liver disease.
• Assess for suicidal ideation: closely observe patients, especially during the initial treatment period.
• Use cautiously in the elderly: increased sensitivity to sedation and anticholinergic effects.
• Avoid abrupt discontinuation: taper the dose gradually to reduce withdrawal symptoms.
• Store at room temperature: keep in the original pack, protect from moisture and light.

Mirtazapine can interact with other medicines, influencing its efficacy or safety.

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): concurrent use may cause hypertensive crisis or serotonin syndrome.
• Potent CYP3A4 inhibitors (e.g., ketoconazole): can markedly increase mirtazapine plasma concentrations.

Moderate Interactions (Monitor Closely)

• CNS depressants (e.g., benzodiazepines, alcohol): may enhance sedation and respiratory depression.
• Other serotonergic agents (e.g., SSRIs, SNRIs): increase risk of serotonin syndrome, requiring dose adjustments.
• Anticholinergic drugs: additive effects on dry mouth and constipation.