Mirtazapin Alternova (Mirtazapine)

Mirtazapine acts on noradrenergic and serotonergic pathways and is indicated for the following depressive conditions.

• Major depressive disorder: reduces depressive symptoms and improves overall mood in adult patients.
• Depressive episodes in bipolar I disorder: used as an adjunct to mood stabilizers to manage depressive phases.
• Depression associated with chronic medical illness: helps alleviate depressive symptoms in patients with comorbid conditions.

• Mirtazapine blocks central presynaptic α2‑adrenergic receptors, increasing release of norepinephrine and serotonin. It also antagonizes postsynaptic 5‑HT2 and 5‑HT3 receptors, and strongly blocks histamine H1 receptors, which together enhance monoaminergic neurotransmission and produce its antidepressant and anxiolytic effects. The combined antagonism reduces inhibitory feedback and modulates serotonergic tone, contributing to improved sleep and appetite, which are often impaired in depression.

Mirtazapine may be associated with a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Drowsiness: feeling of sleepiness or fatigue, especially at treatment initiation.
• Increased appetite and weight gain: heightened hunger leading to gradual weight increase.
• Dry mouth: reduced salivation causing oral discomfort.
• Constipation: slowed gastrointestinal transit resulting in infrequent stools.

Serious or Rare Side Effects

• Agranulocytosis: severe reduction in white blood cells requiring immediate medical attention.
• Seizures: rare occurrence of convulsive episodes, particularly in predisposed individuals.
• Severe hypersensitivity reactions: including rash, angioedema, or anaphylaxis.

Before prescribing mirtazapine, clinicians should consider several precautionary measures to ensure patient safety.

• Assess psychiatric history: evaluate for bipolar disorder or suicidal ideation before initiation.
• Monitor weight and metabolic parameters: track changes in appetite, weight, and lipid profile during therapy.
• Evaluate hepatic and renal function: adjust use in patients with significant liver or kidney impairment.
• Caution in elderly: increased sensitivity to sedation and anticholinergic effects may occur.
• Avoid abrupt discontinuation: taper the dose gradually to reduce risk of withdrawal symptoms.
• Store at ambient temperature: keep below 25 °C in the original container, protected from moisture and light.

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

Major Interactions (Avoid)

• MAO inhibitors: concurrent use may cause hypertensive crisis or serotonin syndrome.
• Strong CYP1A2 inhibitors (e.g., fluvoxamine): can markedly increase mirtazapine plasma concentrations.

Moderate Interactions (Monitor Closely)

• CNS depressants (e.g., benzodiazepines, alcohol): may enhance sedative effects.
• CYP3A4 inducers (e.g., carbamazepine, rifampin): may reduce therapeutic levels of mirtazapine.
• Serotonergic agents (e.g., SSRIs, SNRIs, tramadol): increase risk of serotonin syndrome, requiring monitoring.