Mirtastad (Mirtazapine)

• Mirtazapine is indicated for depressive disorders and is used primarily in the management of major depressive episodes.
• Major depressive disorder: reduces core depressive symptoms such as low mood, loss of interest, and impaired concentration, thereby improving overall functioning in adult patients.
• Treatment‑resistant depression: may be introduced as an adjunct when standard antidepressants (e.g., SSRIs or SNRIs) have not achieved adequate clinical response, offering an alternative mechanism of action.
• Depressive episodes with prominent insomnia or anxiety: helps alleviate sleep disturbances and anxiety symptoms that frequently accompany depression, contributing to better sleep quality and reduced agitation.

• Mirtazapine acts as an antagonist at central presynaptic α2‑adrenergic receptors, which disinhibits norepinephrine release. It also blocks postsynaptic 5‑HT2 and 5‑HT3 receptors and histamine H1 receptors, enhancing serotonergic transmission while reducing serotonergic side‑effects. This pharmacologic profile also contributes to its sedative properties and appetite stimulation, which are clinically relevant.

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

Common Side Effects

• Sedation or drowsiness
• Increased appetite leading to weight gain
• Dry mouth
• Constipation

Serious or Rare Side Effects

• Agranulocytosis or severe neutropenia
• Stevens‑Johnson syndrome or toxic epidermal necrolysis
• Suicidal thoughts or behavior, especially early in treatment
• Hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH)

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

• Monitor weight: patients may experience significant weight gain and should have regular weight checks.
• Assess for suicidal ideation: especially during the initial weeks of therapy or dose changes.
• Evaluate hepatic function: dose adjustment may be needed in severe liver impairment.
• Caution with CNS depressants: concurrent use can enhance sedation and impair psychomotor performance.
• Avoid abrupt discontinuation: tapering is recommended to reduce risk of withdrawal symptoms.
• Store at room temperature (below 25°C): keep in the original container, protect from moisture and direct sunlight.

Mirtazapine can interact with other medicines; awareness of major and moderate interactions helps ensure safe use.

Major Interactions (Avoid)

• Monoamine oxidase inhibitors (MAOIs): concurrent use may cause hypertensive crisis or serotonin syndrome.
• Linezolid or other reversible MAO inhibitors: risk of severe serotonin toxicity.
• Other serotonergic agents (e.g., SSRIs, SNRIs, triptans): increased risk of serotonin syndrome.

Moderate Interactions (Monitor Closely)

• Central nervous system depressants (e.g., benzodiazepines, alcohol): may enhance sedation and respiratory depression.
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): can raise mirtazapine plasma levels.
• Antihypertensive drugs: additive hypotensive effect may occur.
• Anticholinergic medications: may worsen dry mouth and constipation.