Mirtazapina Alter (Mirtazapine)

Mirtazapine is indicated for depressive disorders and related conditions where modulation of norepinephrine and serotonin is therapeutic.

• Major depressive disorder: reduces depressive symptoms and improves overall mood in adult patients.
• Depression with insomnia: promotes sleep onset and maintenance while treating depressive symptoms.
• Depression with anxiety: alleviates anxiety features associated with depressive episodes.

• Mirtazapine acts as an antagonist at 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 serotonergic side‑effects. These actions contribute to its antidepressant and anxiolytic properties, and also affect histamine H1 receptors, which can cause sedation.

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

Common Side Effects

• Drowsiness: feeling of sleepiness or reduced alertness.
• Increased appetite: heightened desire for food, often leading to weight gain.
• Weight gain: noticeable increase in body weight over time.
• Dry mouth: reduced salivation causing oral discomfort.
• Constipation: infrequent or difficult bowel movements.
• Dizziness: sensation of light‑headedness or imbalance.
• Fatigue: persistent feeling of tiredness.
• Nausea: mild stomach upset.

Serious or Rare Side Effects

• Agranulocytosis: severe reduction in white blood cells requiring immediate medical attention.
• Severe allergic reaction: rash, swelling, or difficulty breathing.
• Hepatotoxicity: liver enzyme elevations or liver injury.
• Suicidal thoughts: emergence or worsening of suicidal ideation, especially early in treatment.

When prescribing or dispensing mirtazapine, several precautionary measures should be observed to ensure patient safety.

• Assess psychiatric history: evaluate for prior suicide attempts or depressive severity.
• Monitor weight: track changes due to potential weight gain.
• Check liver function: baseline and periodic liver enzyme testing is advisable.
• Review concomitant CNS depressants: avoid additive sedation with alcohol or benzodiazepines.
• Caution in elderly: increased sensitivity to sedation and orthostatic hypotension.
• Store at ambient temperature: keep below 25 °C in the original packaging, protected from moisture.

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

Major Interactions (Avoid)

• MAO inhibitors: risk of hypertensive crisis; discontinue MAOI at least 14 days before starting.
• CYP2D6 inhibitors: may increase mirtazapine plasma levels, raising side‑effect risk.
• CNS depressants: combined use can cause excessive sedation or respiratory depression.

Moderate Interactions (Monitor Closely)

• Anticoagulants: potential for enhanced bleeding; monitor INR or clotting parameters.
• Serotonergic agents: increased risk of serotonin syndrome; observe for agitation, tremor, hyperreflexia.
• Alcohol: may intensify drowsiness and impair cognition; advise limited consumption.