Mirta (Mirtazapine)

Mirtazapine is a noradrenergic and specific serotonergic antidepressant used in the management of depressive disorders.

• Major depressive disorder: reduces depressive symptoms and improves mood in adult patients.
• Depression with insomnia: promotes sleep onset and improves sleep quality while treating depressive symptoms.
• Depression with anxiety: alleviates anxiety symptoms and enhances overall emotional stability.
• Depressive episodes in bipolar disorder (adjunct): helps control the depressive phase when used with mood stabilizers.

• Mirtazapine acts primarily as an antagonist at central presynaptic α2‑adrenergic receptors, which disinhibits norepinephrine release. It also blocks serotonergic 5‑HT2 and 5‑HT3 receptors and histamine H1 receptors, resulting in increased serotonergic transmission and sedation. The combined antagonism enhances noradrenergic and serotonergic neurotransmission, contributing to its antidepressant and anxiolytic effects. These actions collectively restore the balance of key mood‑regulating pathways in the brain.

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

Common Side Effects

• Sedation: persistent drowsiness or sleepiness that may affect daily activities.
• Increased appetite: heightened desire for food, often accompanied by weight gain.
• Dry mouth: reduced salivation leading to oral discomfort and difficulty swallowing.
• Dizziness: light‑headed sensation, especially upon standing or changing position.

Serious or Rare Side Effects

• Agranulocytosis: severe reduction in white blood cells that can increase infection risk and requires immediate medical evaluation.
• Seizures: rare occurrence of convulsive episodes that may necessitate discontinuation of therapy.
• Hepatotoxicity: potential liver injury manifested by elevated enzymes or jaundice, needing prompt assessment.

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

• Assess hepatic function: evaluate liver enzymes before initiating therapy and monitor periodically.
• Monitor weight changes: track body weight and appetite, especially in patients prone to obesity.
• Evaluate for suicidal thoughts: observe for emergence or worsening of suicidal ideation, particularly early in treatment.
• Review concomitant CNS depressants: avoid or adjust doses of other sedating agents to reduce excessive sedation.
• Caution in the elderly: start at low doses and monitor for increased sensitivity to side effects.
• Store at ambient temperature: keep tablets in the original container, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): concurrent use can cause hypertensive crisis or serotonin syndrome.
• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): may increase mirtazapine plasma levels and risk of toxicity.
• CNS depressants (e.g., benzodiazepines, alcohol): can enhance sedation and respiratory depression.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., carbamazepine, phenytoin): may reduce mirtazapine concentrations, decreasing efficacy.
• Anticholinergic agents (e.g., diphenhydramine): additive dry mouth and constipation may occur.